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1.  Development of silica-encapsulated silver nanoparticle as contrast agents intended for dual-energy mammography 
European radiology  2016;26(9):3301-3309.
Objective
Dual-energy (DE) mammography has recently entered the clinic. Previous theoretical and phantom studies demonstrated that silver provides greater contrast than iodine for this technique. Our objective was to characterize and evaluate in vivo a prototype silver contrast agent ultimately intended for DE mammography.
Methods
The prototype silver contrast agent was synthesized using a three-step process: synthesis of a silver core, silica encapsulation, and PEG coating. The nanoparticles were then injected into mice to determine their accumulation in various organs, blood half-life, and dual-energy contrast. All animal procedures were approved by the Institutional Animal Care and Use Committee.
Results
The final diameter of the nanoparticles was measured to be 102 (± 9) nm. The particles were removed from the vascular circulation with a half-life of 15 minutes, and accumulated in macrophage-rich organs such as the liver, spleen, and lymph nodes. Dual-energy subtraction techniques increased the signal difference-to-noise ratio of the particles by as much as a factor of 15.2 compared to the single-energy images. These nanoparticles produced no adverse effects in mice.
Conclusion
Silver nanoparticles are an effective contrast agent for dual-energy x-ray imaging. With further design improvements, silver nanoparticles may prove valuable in breast cancer screening and diagnosis.
doi:10.1007/s00330-015-4152-y
PMCID: PMC4974128  PMID: 26910906
dual-energy; mammography; nanoparticles; silver, gold; breast cancer
2.  LASIC: Light Activated Site-Specific Conjugation of Native IgGs 
Bioconjugate chemistry  2015;26(8):1456-1460.
Numerous biological applications, from diagnostic assays to immunotherapies, rely on the use of antibody-conjugates. The efficacy of these conjugates can be significantly influenced by the site at which Immunoglobulin G (IgG) is modified. Current methods that provide control over the conjugation site, however, suffer from a number of shortfalls and often require large investments of time and cost. We have developed a novel adapter protein that, when activated by long wavelength UV light, can covalently and site-specifically label the Fc region of nearly any native, full-length IgG, including all human IgG subclasses. Labeling occurs with unprecedented efficiency and speed (>90% after 30 min), with no effect on IgG affinity. The adapter domain can be bacterially expressed and customized to contain a variety of moieties (e.g. biotin, azide, fluorophores), making reliable and efficient conjugation of antibodies widely accessible to researchers at large.
Table of Contents Only
doi:10.1021/acs.bioconjchem.5b00275
PMCID: PMC5507662  PMID: 26057140
3.  Cationic Gadolinium Chelate for Magnetic Resonance Imaging of Cartilaginous Defects 
The ability to detect meniscus defects by magnetic resonance arthrography (MRA) can be highly variable. To improve the delineation of fine tears, we synthesized a cationic gadolinium complex, (Gd-DOTA-AM4)2+, that can electrostatically interact with Glycosaminoglycans (GAGs). The complex has a longitudinal relaxivity (r1) of 4.2 mM−1s−1 and is highly stable in serum. Its efficacy in highlighting soft tissue tears was evaluated in comparison to a clinically employed contrast agent (Magnevist) using explants obtained from adult bovine menisci. In all cases, Gd-DOTA-AM4 appeared to improve the ability to detect the soft tissue defect by providing increased signal intensity along the length of the tear. Magnevist shows a strong signal near the liquid-meniscus interface, but much less contrast is observed within the defect at greater depths. This provides initial evidence that cationic contrast agents can be used to improve the diagnostic accuracy of MRA.
doi:10.1002/cmmi.1685
PMCID: PMC4892988  PMID: 26853708
gadolinium; MRA; magnetic resonance arthrography; imaging; chelate; DOTA; magenevist; cationic
4.  31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016): part one 
Lundqvist, Andreas | van Hoef, Vincent | Zhang, Xiaonan | Wennerberg, Erik | Lorent, Julie | Witt, Kristina | Sanz, Laia Masvidal | Liang, Shuo | Murray, Shannon | Larsson, Ola | Kiessling, Rolf | Mao, Yumeng | Sidhom, John-William | Bessell, Catherine A. | Havel, Jonathan | Schneck, Jonathan | Chan, Timothy A. | Sachsenmeier, Eliot | Woods, David | Berglund, Anders | Ramakrishnan, Rupal | Sodre, Andressa | Weber, Jeffrey | Zappasodi, Roberta | Li, Yanyun | Qi, Jingjing | Wong, Philip | Sirard, Cynthia | Postow, Michael | Newman, Walter | Koon, Henry | Velcheti, Vamsidhar | Callahan, Margaret K. | Wolchok, Jedd D. | Merghoub, Taha | Lum, Lawrence G. | Choi, Minsig | Thakur, Archana | Deol, Abhinav | Dyson, Gregory | Shields, Anthony | Haymaker, Cara | Uemura, Marc | Murthy, Ravi | James, Marihella | Wang, Daqing | Brevard, Julie | Monaghan, Catherine | Swann, Suzanne | Geib, James | Cornfeld, Mark | Chunduru, Srinivas | Agrawal, Sudhir | Yee, Cassian | Wargo, Jennifer | Patel, Sapna P. | Amaria, Rodabe | Tawbi, Hussein | Glitza, Isabella | Woodman, Scott | Hwu, Wen-Jen | Davies, Michael A. | Hwu, Patrick | Overwijk, Willem W. | Bernatchez, Chantale | Diab, Adi | Massarelli, Erminia | Segal, Neil H. | Ribrag, Vincent | Melero, Ignacio | Gangadhar, Tara C. | Urba, Walter | Schadendorf, Dirk | Ferris, Robert L. | Houot, Roch | Morschhauser, Franck | Logan, Theodore | Luke, Jason J. | Sharfman, William | Barlesi, Fabrice | Ott, Patrick A. | Mansi, Laura | Kummar, Shivaani | Salles, Gilles | Carpio, Cecilia | Meier, Roland | Krishnan, Suba | McDonald, Dan | Maurer, Matthew | Gu, Xuemin | Neely, Jaclyn | Suryawanshi, Satyendra | Levy, Ronald | Khushalani, Nikhil | Wu, Jennifer | Zhang, Jinyu | Basher, Fahmin | Rubinstein, Mark | Bucsek, Mark | Qiao, Guanxi | MacDonald, Cameron | Hylander, Bonnie | Repasky, Elizabeth | Chatterjee, Shilpak | Daenthanasanmak, Anusara | Chakraborty, Paramita | Toth, Kyle | Meek, Megan | Garrett-Mayer, Elizabeth | Nishimura, Michael | Paulos, Chrystal | Beeson, Craig | Yu, Xuezhong | Mehrotra, Shikhar | Zhao, Fei | Evans, Kathy | Xiao, Christine | Holtzhausen, Alisha | Hanks, Brent A. | Scharping, Nicole | Menk, Ashley V. | Moreci, Rebecca | Whetstone, Ryan | Dadey, Rebekah | Watkins, Simon | Ferris, Robert | Delgoffe, Greg M. | Peled, Jonathan | Devlin, Sean | Staffas, Anna | Lumish, Melissa | Rodriguez, Kori Porosnicu | Ahr, Katya | Perales, Miguel | Giralt, Sergio | Taur, Ying | Pamer, Eric | van den Brink, Marcel R. M. | Jenq, Robert | Annels, Nicola | Pandha, Hardev | Simpson, Guy | Mostafid, Hugh | Harrington, Kevin | Melcher, Alan | Grose, Mark | Davies, Bronwyn | Au, Gough | Karpathy, Roberta | Shafren, Darren | Ricca, Jacob | Merghoub, Taha | Wolchok, Jedd D. | Zamarin, Dmitriy | Batista, Luciana | Marliot, Florence | Vasaturo, Angela | Carpentier, Sabrina | Poggionovo, Cécile | Frayssinet, Véronique | Fieschi, Jacques | Van den Eynde, Marc | Pagès, Franck | Galon, Jérôme | Hermitte, Fabienne | Smith, Sean G. | Nguyen, Khue | Ravindranathan, Sruthi | Koppolu, Bhanu | Zaharoff, David | Schvartsman, Gustavo | Bassett, Roland | McQuade, Jennifer L. | Haydu, Lauren E. | Davies, Michael A. | Tawbi, Hussein | Glitza, Isabella | Kline, Douglas | Chen, Xiufen | Fosco, Dominick | Kline, Justin | Overacre, Abigail | Chikina, Maria | Brunazzi, Erin | Shayan, Gulidanna | Horne, William | Kolls, Jay | Ferris, Robert L. | Delgoffe, Greg M. | Bruno, Tullia C. | Workman, Creg | Vignali, Dario | Adusumilli, Prasad S. | Ansa-Addo, Ephraim A | Li, Zihai | Gerry, Andrew | Sanderson, Joseph P. | Howe, Karen | Docta, Roslin | Gao, Qian | Bagg, Eleanor A. L. | Tribble, Nicholas | Maroto, Miguel | Betts, Gareth | Bath, Natalie | Melchiori, Luca | Lowther, Daniel E. | Ramachandran, Indu | Kari, Gabor | Basu, Samik | Binder-Scholl, Gwendolyn | Chagin, Karen | Pandite, Lini | Holdich, Tom | Amado, Rafael | Zhang, Hua | Glod, John | Bernstein, Donna | Jakobsen, Bent | Mackall, Crystal | Wong, Ryan | Silk, Jonathan D. | Adams, Katherine | Hamilton, Garth | Bennett, Alan D. | Brett, Sara | Jing, Junping | Quattrini, Adriano | Saini, Manoj | Wiedermann, Guy | Gerry, Andrew | Jakobsen, Bent | Binder-Scholl, Gwendolyn | Brewer, Joanna | Duong, MyLinh | Lu, An | Chang, Peter | Mahendravada, Aruna | Shinners, Nicholas | Slawin, Kevin | Spencer, David M. | Foster, Aaron E. | Bayle, J. Henri | Bergamaschi, Cristina | Ng, Sinnie Sin Man | Nagy, Bethany | Jensen, Shawn | Hu, Xintao | Alicea, Candido | Fox, Bernard | Felber, Barbara | Pavlakis, George | Chacon, Jessica | Yamamoto, Tori | Garrabrant, Thomas | Cortina, Luis | Powell, Daniel J. | Donia, Marco | Kjeldsen, Julie Westerlin | Andersen, Rikke | Westergaard, Marie Christine Wulff | Bianchi, Valentina | Legut, Mateusz | Attaf, Meriem | Dolton, Garry | Szomolay, Barbara | Ott, Sascha | Lyngaa, Rikke | Hadrup, Sine Reker | Sewell, Andrew Kelvin | Svane, Inge Marie | Fan, Aaron | Kumai, Takumi | Celis, Esteban | Frank, Ian | Stramer, Amanda | Blaskovich, Michelle A. | Wardell, Seth | Fardis, Maria | Bender, James | Lotze, Michael T. | Goff, Stephanie L. | Zacharakis, Nikolaos | Assadipour, Yasmine | Prickett, Todd D. | Gartner, Jared J. | Somerville, Robert | Black, Mary | Xu, Hui | Chinnasamy, Harshini | Kriley, Isaac | Lu, Lily | Wunderlich, John | Robbins, Paul F. | Rosenberg, Steven | Feldman, Steven A. | Trebska-McGowan, Kasia | Kriley, Isaac | Malekzadeh, Parisa | Payabyab, Eden | Sherry, Richard | Rosenberg, Steven | Goff, Stephanie L. | Gokuldass, Aishwarya | Blaskovich, Michelle A. | Kopits, Charlene | Rabinovich, Brian | Lotze, Michael T. | Green, Daniel S. | Kamenyeva, Olena | Zoon, Kathryn C. | Annunziata, Christina M. | Hammill, Joanne | Helsen, Christopher | Aarts, Craig | Bramson, Jonathan | Harada, Yui | Yonemitsu, Yoshikazu | Helsen, Christopher | Hammill, Joanne | Mwawasi, Kenneth | Denisova, Galina | Bramson, Jonathan | Giri, Rajanish | Jin, Benjamin | Campbell, Tracy | Draper, Lindsey M. | Stevanovic, Sanja | Yu, Zhiya | Weissbrich, Bianca | Restifo, Nicholas P. | Trimble, Cornelia L. | Rosenberg, Steven | Hinrichs, Christian S. | Tsang, Kwong | Fantini, Massimo | Hodge, James W. | Fujii, Rika | Fernando, Ingrid | Jochems, Caroline | Heery, Christopher | Gulley, James | Soon-Shiong, Patrick | Schlom, Jeffrey | Jing, Weiqing | Gershan, Jill | Blitzer, Grace | Weber, James | McOlash, Laura | Johnson, Bryon D. | Kiany, Simin | Gangxiong, Huang | Kleinerman, Eugenie S. | Klichinsky, Michael | Ruella, Marco | Shestova, Olga | Kenderian, Saad | Kim, Miriam | Scholler, John | June, Carl H. | Gill, Saar | Moogk, Duane | Zhong, Shi | Yu, Zhiya | Liadi, Ivan | Rittase, William | Fang, Victoria | Dougherty, Janna | Perez-Garcia, Arianne | Osman, Iman | Zhu, Cheng | Varadarajan, Navin | Restifo, Nicholas P. | Frey, Alan | Krogsgaard, Michelle | Landi, Daniel | Fousek, Kristen | Mukherjee, Malini | Shree, Ankita | Joseph, Sujith | Bielamowicz, Kevin | Byrd, Tiara | Ahmed, Nabil | Hegde, Meenakshi | Lee, Sylvia | Byrd, David | Thompson, John | Bhatia, Shailender | Tykodi, Scott | Delismon, Judy | Chu, Liz | Abdul-Alim, Siddiq | Ohanian, Arpy | DeVito, Anna Marie | Riddell, Stanley | Margolin, Kim | Magalhaes, Isabelle | Mattsson, Jonas | Uhlin, Michael | Nemoto, Satoshi | Villarroel, Patricio Pérez | Nakagawa, Ryosuke | Mule, James J. | Mailloux, Adam W. | Mata, Melinda | Nguyen, Phuong | Gerken, Claudia | DeRenzo, Christopher | Spencer, David M. | Gottschalk, Stephen | Mathieu, Mélissa | Pelletier, Sandy | Stagg, John | Turcotte, Simon | Minutolo, Nicholas | Sharma, Prannda | Tsourkas, Andrew | Powell, Daniel J. | Mockel-Tenbrinck, Nadine | Mauer, Daniela | Drechsel, Katharina | Barth, Carola | Freese, Katharina | Kolrep, Ulrike | Schult, Silke | Assenmacher, Mario | Kaiser, Andrew | Mullinax, John | Hall, MacLean | Le, Julie | Kodumudi, Krithika | Royster, Erica | Richards, Allison | Gonzalez, Ricardo | Sarnaik, Amod | Pilon-Thomas, Shari | Nielsen, Morten | Krarup-Hansen, Anders | Hovgaard, Dorrit | Petersen, Michael Mørk | Loya, Anand Chainsukh | Junker, Niels | Svane, Inge Marie | Rivas, Charlotte | Parihar, Robin | Gottschalk, Stephen | Rooney, Cliona M. | Qin, Haiying | Nguyen, Sang | Su, Paul | Burk, Chad | Duncan, Brynn | Kim, Bong-Hyun | Kohler, M. Eric | Fry, Terry | Rao, Arjun A. | Teyssier, Noam | Pfeil, Jacob | Sgourakis, Nikolaos | Salama, Sofie | Haussler, David | Richman, Sarah A. | Nunez-Cruz, Selene | Gershenson, Zack | Mourelatos, Zissimos | Barrett, David | Grupp, Stephan | Milone, Michael | Rodriguez-Garcia, Alba | Robinson, Matthew K. | Adams, Gregory P. | Powell, Daniel J. | Santos, João | Havunen, Riikka | Siurala, Mikko | Cervera-Carrascón, Víctor | Parviainen, Suvi | Antilla, Marjukka | Hemminki, Akseli | Sethuraman, Jyothi | Santiago, Laurelis | Chen, Jie Qing | Dai, Zhimin | Wardell, Seth | Bender, James | Lotze, Michael T. | Sha, Huizi | Su, Shu | Ding, Naiqing | Liu, Baorui | Stevanovic, Sanja | Pasetto, Anna | Helman, Sarah R. | Gartner, Jared J. | Prickett, Todd D. | Robbins, Paul F. | Rosenberg, Steven A. | Hinrichs, Christian S. | Bhatia, Shailender | Burgess, Melissa | Zhang, Hui | Lee, Tien | Klingemann, Hans | Soon-Shiong, Patrick | Nghiem, Paul | Kirkwood, John M. | Rossi, John M. | Sherman, Marika | Xue, Allen | Shen, Yueh-wei | Navale, Lynn | Rosenberg, Steven A. | Kochenderfer, James N. | Bot, Adrian | Veerapathran, Anandaraman | Gokuldass, Aishwarya | Stramer, Amanda | Sethuraman, Jyothi | Blaskovich, Michelle A. | Wiener, Doris | Frank, Ian | Santiago, Laurelis | Rabinovich, Brian | Fardis, Maria | Bender, James | Lotze, Michael T. | Waller, Edmund K. | Li, Jian-Ming | Petersen, Christopher | Blazar, Bruce R. | Li, Jingxia | Giver, Cynthia R. | Wang, Ziming | Grossenbacher, Steven K. | Sturgill, Ian | Canter, Robert J. | Murphy, William J. | Zhang, Congcong | Burger, Michael C. | Jennewein, Lukas | Waldmann, Anja | Mittelbronn, Michel | Tonn, Torsten | Steinbach, Joachim P. | Wels, Winfried S. | Williams, Jason B. | Zha, Yuanyuan | Gajewski, Thomas F. | Williams, LaTerrica C. | Krenciute, Giedre | Kalra, Mamta | Louis, Chrystal | Gottschalk, Stephen | Xin, Gang | Schauder, David | Jiang, Aimin | Joshi, Nikhil | Cui, Weiguo | Zeng, Xue | Menk, Ashley V. | Scharping, Nicole | Delgoffe, Greg M. | Zhao, Zeguo | Hamieh, Mohamad | Eyquem, Justin | Gunset, Gertrude | Bander, Neil | Sadelain, Michel | Askmyr, David | Abolhalaj, Milad | Lundberg, Kristina | Greiff, Lennart | Lindstedt, Malin | Angell, Helen K. | Kim, Kyoung-Mee | Kim, Seung-Tae | Kim, Sung | Sharpe, Alan D. | Ogden, Julia | Davenport, Anna | Hodgson, Darren R. | Barrett, Carl | Lee, Jeeyun | Kilgour, Elaine | Hanson, Jodi | Caspell, Richard | Karulin, Alexey | Lehmann, Paul | Ansari, Tameem | Schiller, Annemarie | Sundararaman, Srividya | Lehmann, Paul | Hanson, Jodi | Roen, Diana | Karulin, Alexey | Lehmann, Paul | Ayers, Mark | Levitan, Diane | Arreaza, Gladys | Liu, Fang | Mogg, Robin | Bang, Yung-Jue | O’Neil, Bert | Cristescu, Razvan | Friedlander, Philip | Wassman, Karl | Kyi, Chrisann | Oh, William | Bhardwaj, Nina | Bornschlegl, Svetlana | Gustafson, Michael P. | Gastineau, Dennis A. | Parney, Ian F. | Dietz, Allan B. | Carvajal-Hausdorf, Daniel | Mani, Nikita | Velcheti, Vamsidhar | Schalper, Kurt | Rimm, David | Chang, Serena | Levy, Ronald | Kurland, John | Krishnan, Suba | Ahlers, Christoph Matthias | Jure-Kunkel, Maria | Cohen, Lewis | Maecker, Holden | Kohrt, Holbrook | Chen, Shuming | Crabill, George | Pritchard, Theresa | McMiller, Tracee | Pardoll, Drew | Pan, Fan | Topalian, Suzanne | Danaher, Patrick | Warren, Sarah | Dennis, Lucas | White, Andrew M. | D’Amico, Leonard | Geller, Melissa | Disis, Mary L. | Beechem, Joseph | Odunsi, Kunle | Fling, Steven | Derakhshandeh, Roshanak | Webb, Tonya J. | Dubois, Sigrid | Conlon, Kevin | Bryant, Bonita | Hsu, Jennifer | Beltran, Nancy | Müller, Jürgen | Waldmann, Thomas | Duhen, Rebekka | Duhen, Thomas | Thompson, Lucas | Montler, Ryan | Weinberg, Andrew | Kates, Max | Early, Brandon | Yusko, Erik | Schreiber, Taylor H. | Bivalacqua, Trinity J. | Ayers, Mark | Lunceford, Jared | Nebozhyn, Michael | Murphy, Erin | Loboda, Andrey | Kaufman, David R. | Albright, Andrew | Cheng, Jonathan | Kang, S. Peter | Shankaran, Veena | Piha-Paul, Sarina A. | Yearley, Jennifer | Seiwert, Tanguy | Ribas, Antoni | McClanahan, Terrill K. | Cristescu, Razvan | Mogg, Robin | Ayers, Mark | Albright, Andrew | Murphy, Erin | Yearley, Jennifer | Sher, Xinwei | Liu, Xiao Qiao | Nebozhyn, Michael | Lunceford, Jared | Joe, Andrew | Cheng, Jonathan | Plimack, Elizabeth | Ott, Patrick A. | McClanahan, Terrill K. | Loboda, Andrey | Kaufman, David R. | Forrest-Hay, Alex | Guyre, Cheryl A. | Narumiya, Kohei | Delcommenne, Marc | Hirsch, Heather A. | Deshpande, Amit | Reeves, Jason | Shu, Jenny | Zi, Tong | Michaelson, Jennifer | Law, Debbie | Trehu, Elizabeth | Sathyanaryanan, Sriram | Hodkinson, Brendan P. | Hutnick, Natalie A. | Schaffer, Michael E. | Gormley, Michael | Hulett, Tyler | Jensen, Shawn | Ballesteros-Merino, Carmen | Dubay, Christopher | Afentoulis, Michael | Reddy, Ashok | David, Larry | Fox, Bernard | Jayant, Kumar | Agrawal, Swati | Agrawal, Rajendra | Jeyakumar, Ghayathri | Kim, Seongho | Kim, Heejin | Silski, Cynthia | Suisham, Stacey | Heath, Elisabeth | Vaishampayan, Ulka | Vandeven, Natalie | Viller, Natasja Nielsen | O’Connor, Alison | Chen, Hui | Bossen, Bolette | Sievers, Eric | Uger, Robert | Nghiem, Paul | Johnson, Lisa | Kao, Hsiang-Fong | Hsiao, Chin-Fu | Lai, Shu-Chuan | Wang, Chun-Wei | Ko, Jenq-Yuh | Lou, Pei-Jen | Lee, Tsai-Jan | Liu, Tsang-Wu | Hong, Ruey-Long | Kearney, Staci J. | Black, Joshua C. | Landis, Benjamin J. | Koegler, Sally | Hirsch, Brooke | Gianani, Roberto | Kim, Jeffrey | He, Ming-Xiao | Zhang, Bingqing | Su, Nan | Luo, Yuling | Ma, Xiao-Jun | Park, Emily | Kim, Dae Won | Copploa, Domenico | Kothari, Nishi | doo Chang, Young | Kim, Richard | Kim, Namyong | Lye, Melvin | Wan, Ee | Kim, Namyong | Lye, Melvin | Wan, Ee | Kim, Namyong | Lye, Melvin | Wan, Ee | Knaus, Hanna A. | Berglund, Sofia | Hackl, Hubert | Karp, Judith E. | Gojo, Ivana | Luznik, Leo | Hong, Henoch S. | Koch, Sven D. | Scheel, Birgit | Gnad-Vogt, Ulrike | Kallen, Karl-Josef | Wiegand, Volker | Backert, Linus | Kohlbacher, Oliver | Hoerr, Ingmar | Fotin-Mleczek, Mariola | Billingsley, James M. | Koguchi, Yoshinobu | Conrad, Valerie | Miller, William | Gonzalez, Iliana | Poplonski, Tomasz | Meeuwsen, Tanisha | Howells-Ferreira, Ana | Rattray, Rogan | Campbell, Mary | Bifulco, Carlo | Dubay, Christopher | Bahjat, Keith | Curti, Brendan | Urba, Walter | Vetsika, E-K | Kallergi, G. | Aggouraki, Despoina | Lyristi, Z. | Katsarlinos, P. | Koinis, Filippos | Georgoulias, V. | Kotsakis, Athanasios | Martin, Nathan T. | Aeffner, Famke | Kearney, Staci J. | Black, Joshua C. | Cerkovnik, Logan | Pratte, Luke | Kim, Rebecca | Hirsch, Brooke | Krueger, Joseph | Gianani, Roberto | Martínez-Usatorre, Amaia | Jandus, Camilla | Donda, Alena | Carretero-Iglesia, Laura | Speiser, Daniel E. | Zehn, Dietmar | Rufer, Nathalie | Romero, Pedro | Panda, Anshuman | Mehnert, Janice | Hirshfield, Kim M. | Riedlinger, Greg | Damare, Sherri | Saunders, Tracie | Sokol, Levi | Stein, Mark | Poplin, Elizabeth | Rodriguez-Rodriguez, Lorna | Silk, Ann | Chan, Nancy | Frankel, Melissa | Kane, Michael | Malhotra, Jyoti | Aisner, Joseph | Kaufman, Howard L. | Ali, Siraj | Ross, Jeffrey | White, Eileen | Bhanot, Gyan | Ganesan, Shridar | Monette, Anne | Bergeron, Derek | Amor, Amira Ben | Meunier, Liliane | Caron, Christine | Morou, Antigoni | Kaufmann, Daniel | Liberman, Moishe | Jurisica, Igor | Mes-Masson, Anne-Marie | Hamzaoui, Kamel | Lapointe, Rejean | Mongan, Ann | Ku, Yuan-Chieh | Tom, Warren | Sun, Yongming | Pankov, Alex | Looney, Tim | Au-Young, Janice | Hyland, Fiona | Conroy, Jeff | Morrison, Carl | Glenn, Sean | Burgher, Blake | Ji, He | Gardner, Mark | Mongan, Ann | Omilian, Angela R. | Conroy, Jeff | Bshara, Wiam | Angela, Omilian | Burgher, Blake | Ji, He | Glenn, Sean | Morrison, Carl | Mongan, Ann | Obeid, Joseph M. | Erdag, Gulsun | Smolkin, Mark E. | Deacon, Donna H. | Patterson, James W. | Chen, Lieping | Bullock, Timothy N. | Slingluff, Craig L. | Obeid, Joseph M. | Erdag, Gulsun | Deacon, Donna H. | Slingluff, Craig L. | Bullock, Timothy N. | Loffredo, John T. | Vuyyuru, Raja | Beyer, Sophie | Spires, Vanessa M. | Fox, Maxine | Ehrmann, Jon M. | Taylor, Katrina A. | Korman, Alan J. | Graziano, Robert F. | Page, David | Sanchez, Katherine | Ballesteros-Merino, Carmen | Martel, Maritza | Bifulco, Carlo | Urba, Walter | Fox, Bernard | Patel, Sapna P. | De Macedo, Mariana Petaccia | Qin, Yong | Reuben, Alex | Spencer, Christine | Guindani, Michele | Bassett, Roland | Wargo, Jennifer | Racolta, Adriana | Kelly, Brian | Jones, Tobin | Polaske, Nathan | Theiss, Noah | Robida, Mark | Meridew, Jeffrey | Habensus, Iva | Zhang, Liping | Pestic-Dragovich, Lidija | Tang, Lei | Sullivan, Ryan J. | Logan, Theodore | Khushalani, Nikhil | Margolin, Kim | Koon, Henry | Olencki, Thomas | Hutson, Thomas | Curti, Brendan | Roder, Joanna | Blackmon, Shauna | Roder, Heinrich | Stewart, John | Amin, Asim | Ernstoff, Marc S. | Clark, Joseph I. | Atkins, Michael B. | Kaufman, Howard L. | Sosman, Jeffrey | Weber, Jeffrey | McDermott, David F. | Weber, Jeffrey | Kluger, Harriet | Halaban, Ruth | Snzol, Mario | Roder, Heinrich | Roder, Joanna | Asmellash, Senait | Steingrimsson, Arni | Blackmon, Shauna | Sullivan, Ryan J. | Wang, Chichung | Roman, Kristin | Clement, Amanda | Downing, Sean | Hoyt, Clifford | Harder, Nathalie | Schmidt, Guenter | Schoenmeyer, Ralf | Brieu, Nicolas | Yigitsoy, Mehmet | Madonna, Gabriele | Botti, Gerardo | Grimaldi, Antonio | Ascierto, Paolo A. | Huss, Ralf | Athelogou, Maria | Hessel, Harald | Harder, Nathalie | Buchner, Alexander | Schmidt, Guenter | Stief, Christian | Huss, Ralf | Binnig, Gerd | Kirchner, Thomas | Sellappan, Shankar | Thyparambil, Sheeno | Schwartz, Sarit | Cecchi, Fabiola | Nguyen, Andrew | Vaske, Charles | Hembrough, Todd
Journal for Immunotherapy of Cancer  2016;4(Suppl 1):1-106.
doi:10.1186/s40425-016-0172-7
PMCID: PMC5123387
5.  Biodistribution, Clearance, and Toxicology of Polymeric Micelles Loaded with 0.9 or 5 nm Gold Nanoparticles 
Journal of biomedical nanotechnology  2015;11(10):1836-1846.
Long-circulating gold nanoparticles (AuNPs) have garnered a great deal of interest as both imaging and therapeutic agents. However, their protracted elimination and long-term persistence within many organ systems remains a concern for clinical translation. To improve the excretion of long-circulating nanoparticles, we prepared ~80 nm biodegradable polymeric micelles with 0.9 nm or 5 nm AuNPs tightly packed within the hydrophobic core. These gold-loaded polymeric micelles (GPMs) were expected to allow for improved excretion of gold, compared with single large AuNPs, owing to the smaller size and larger surface-to-volume ratio of the individual AuNPs within the micelle. Following intravenous administration of GPMs, organs were harvested and examined for gold content using inductively coupled plasma optical emission spectrometry (ICP-OES) for up to 3 months post-injection. While both GPM formulations showed significant clearance of gold over time, micelles containing 0.9 nm AuNPs showed a 72% and 67% reduction in gold content in the liver and spleen, respectively, between 1 day and 3 months post-injection, compared with a 38% and 35% reduction in mice receiving 5 nm GPMs. Furthermore, feces and urine analysis revealed approximately 7.5 and 100 times more gold, respectively, in mice that received 0.9 nm GPMs one day after injection. These findings suggest that the excretion profile of inorganic nanomaterials may be improved if clusters of small inorganic materials are used in favor of single solid particles.
PMCID: PMC4942304  PMID: 26502646
Gold; Nanoparticles; Biodistribution; Pharmacokinetics; Excretion; Elimination; Clearance; Toxicity
6.  PLA2-responsive and SPIO-loaded phospholipid micelles 
A PLA2-responsive and superparamagnetic iron oxide (SPIO) nanoparticle-loaded phospholipid micelle was developed. The release of phospholipid-conjugated dye from these micelles was triggered due to phospholipid degradation by phospholipase A2. High relaxivity of the encapsulated SPIO could enable non-invasive magnetic resonance imaging.
doi:10.1039/c5cc04540a
PMCID: PMC4506235  PMID: 26139589
7.  Theranostic Application of Mixed Gold and Superparamagnetic Iron Oxide Nanoparticle Micelles in Glioblastoma Multiforme 
The treatment of glioblastoma multiforme, the most prevalent and lethal form of brain cancer in humans, has been limited in part by poor delivery of drugs through the blood-brain barrier and by unclear delineation of the extent of infiltrating tumor margins. Nanoparticles, which selectively accumulate in tumor tissue due to their leaky vasculature and the enhanced permeability and retention effect, have shown promise as both therapeutic and diagnostic agents for brain tumors. In particular, superparamagnetic iron oxide nanoparticles (SPIONs) have been leveraged as T2-weighted MRI contrast agents for tumor detection and imaging; and gold nanoparticles (AuNP) have been demonstrated as radiosensitizers capable of propagating electron and free radical-induced radiation damage to tumor cells. In this study, we investigated the potential applications of novel gold and SPION-loaded micelles (GSMs) coated by polyethylene glycol-polycaprolactone (PEG-PCL) polymer. By quantifying gh2ax DNA damage foci in glioblastoma cell lines, we tested the radiosensitizing efficacy of these GSMs, and found that GSM administration in conjunction with radiation therapy (RT) led to ~2-fold increase in density of double-stranded DNA breaks. For imaging, we used GSMs as a contrast agent for both computed tomography (CT) and magnetic resonance imaging (MRI) studies of stereotactically implanted GBM tumors in a mouse model, and found that MRI but not CT was sufficiently sensitive to detect and delineate tumor borders after administration and accumulation of GSMs. These results suggest that with further development and testing, GSMs may potentially be integrated into both imaging and treatment of brain tumors, serving a theranostic purpose as both an MRI-based contrast agent and a radiosensitizer.
PMCID: PMC4942305  PMID: 27305768
Gold Nanoparticle; Superparamagnetic Iron Nanoparticle; Glioblastoma Multiforme; Radiotherapy; Magnetic Resonance Imaging; Contrast Agent
8.  Superparamagnetic Iron Oxide Nanoparticle Micelles Stabilized by Recombinant Oleosin for Targeted Magnetic Resonance Imaging 
Recombinant surfactants present a new platform for stabilizing and targeting nanoparticle imaging agents. Superparamagnetic iron oxide nanoparticle-loaded micelles for MRI contrast are stabilized by an engineered variant of the naturally occurring protein oleosin and targeted using a Her2/neu affibody-oleosin fusion. The recombinant oleosin platform allows for simple targeting and the ability to easily swap of the ligand for numerous targets.
doi:10.1002/smll.201402017
PMCID: PMC4746475  PMID: 25418741
Oleosin; MRI contrast; iron oxide; recombinant surfactant; targeting
9.  A Novel Chitosan-Hydrogel-Based Nanoparticle Delivery System for Local Inner Ear Application 
Hypothesis
A chitosan-hydrogel-based nanoparticle (nanohydrogel) delivery system can be used to deliver therapeutic biomaterials across the round window membrane (RWM) into the inner ear in a mouse model.
Background
Delivering therapies to the inner ear has always been a challenge for the Otolaryngologist. Advances in biomedical nanotechnology, increased understanding of the RWM diffusion properties, and discovery of novel therapeutic targets and agents, have all sparked interest in the controlled local delivery of drugs and biomaterials to the inner ear using nanoparticles (NPs).
Methods
Fluorescently-labeled liposomal NPs were constructed and loaded into a chitosan-based hydrogel to form a nanohydrogel, and in vitro studies were performed to evaluate its properties and release kinetics. Furthermore, the nanohydrogel was applied to the RWM of mice, and perilymph and morphologic analysis were performed to assess the NP delivery and distribution within the inner ear.
Results
NPs with an average diameter of 160nm were obtained. In vitro experiments showed that liposomal NPs can persist under physiologic conditions for at least two weeks without significant degradation, and that the nanohydrogel can carry and release these NPs in a controlled and sustained manner. In vivo findings demonstrated that the nanohydrogel can deliver intact nanoparticles into the perilymphatic system and reach cellular structures in the scala media of the inner ear of our mouse model.
Conclusion
Our study suggests that the nanohydrogel system has great potential to deliver therapeutics in a controlled and sustained manner from the middle ear to the inner ear without altering inner ear structures.
doi:10.1097/MAO.0000000000000445
PMCID: PMC4365436  PMID: 25587675
10.  A simple method for the synthesis of porous polymeric vesicles and their application as MR contrast agents 
Because of their low membrane permeability the use of polymeric vesicles in certain drug delivery and molecular imaging applications and as bioreactors is less than ideal. Here, we report a simple method to prepare porous polymeric vesicles that possess high membrane permeability. Specifically, porous vesicles were produced from the aqueous assembly of the diblock copolymer PEG-PBD, and the triblock copolymer PEG-PPO-PEG. It was found that PEG-PPO-PEG-doped polymersomes exhibited improved membrane permeability to molecules less than 5 kDa. Further, these porous vesicles retained molecules ≥10 kDa within their aqueous interiors with no significant leakage. To demonstrate its application, highly efficient magnetic resonance contrast agents were produced from porous polymersomes by encapsulating macromolecules labeled with gadolinium. Due to a fast water exchange rate with surrounding bulk water, these paramagnetic porous polymersomes exhibited higher r1 relaxivity compared with Gd-encapsulated vesicles with no pores. Due to their simplicity, the porous polymersomes prepared with this method are expected to have additional useful applications.
doi:10.1039/C5TB02067K
PMCID: PMC4675335  PMID: 26693022
11.  Dextran coated bismuth-iron oxide nanohybrid contrast agents for computed tomography and magnetic resonance imaging 
Bismuth nanoparticles have been proposed as a novel CT contrast agent, however few syntheses of biocompatible bismuth nanoparticles have been achieved. We herein report the synthesis of composite bismuth-iron oxide nanoparticles (BION) that are based on a clinically approved, dextran-coated iron oxide formulation; the particles have the advantage of acting as contrast agents for both CT and MRI. BION were synthesized and characterized using various analytical methods. BION CT phantom images revealed that the X-ray attenuation of the different formulations was dependent upon the amount of bismuth present in the nanoparticle, while T2-weighted MRI contrast decreased with increasing bismuth content. No cytotoxicity was observed in Hep G2 and BJ5ta cells after 24 hours incubation with BION. The above properties, as well as the yield of synthesis and bismuth inclusion efficiency, led us to select the Bi-30 formulation for in vivo experiments, performed in mice using a micro-CT and a 9.4 T MRI system. X-ray contrast was observed in the heart and blood vessels over a 2 hour period, indicating that Bi-30 has a prolonged circulation half-life. Considerable signal loss in T2-weighted MR images was observed in the liver compared to pre-injection scans. Evaluation of the biodistribution of Bi-30 revealed that bismuth is excreted via the urine, with significant concentrations found in the kidneys and urine. In vitro experiments confirmed the degradability of Bi-30. In summary, dextran coated BION are biocompatible, biodegradable, possess strong X-ray attenuation properties and also can be used as T2-weighted MR contrast agents.
doi:10.1039/C4TB01159G
PMCID: PMC4251562  PMID: 25485115
Bismuth; iron oxide; nanoparticle; contrast agent; computed tomography; magnetic resonance imaging
12.  Nanoparticles functionalized with collagenase exhibit improved tumor accumulation in a murine xenograft model 
Nanoparticles have garnered widespread interest for both the imaging and treatment of cancer due to their unique and tunable pharmacokinetics and their ability to carry a high payload of diverse compounds. However, despite these favorable attributes, the extent of tumor accumulation can be severely restricted due to the dense stroma surrounding the often-permeable blood vessel wall and high intratumoral pressure. In this study, we investigated whether modifying the surface of pegylated gold nanoparticles (AuNPs) with collagenase could improve the accumulation of nanoparticles within a murine tumor xenograft. It was determined that collagenase remains active after surface conjugation and the presence of collagenase has no measureable effect on cell proliferation in vitro. Following intravenous injection, the largest fractions of collagenase-labeled AuNPs were found in the liver and spleen. Histological analysis revealed no signs of toxicity in either of these organs. Blood chemistry revealed normal levels of liver enzymes, but a slightly elevated level of total bilirubin. Within the tumor, AuNPs labeled with collagenase exhibited a 35% increase in accumulation compared with unlabeled AuNPs. Therefore, these studies provide preliminary evidence that the functionalization of nanoparticles with collagenase represent an effective and safe approach to improve tumor accumulation.
doi:10.1002/ppsc.201400169
PMCID: PMC4569138  PMID: 26380538
nanoparticles; collagenase; tumor; penetration; stroma
14.  Nanodisco Balls: Control over Surface versus Core Loading of Diagnostically Active Nanocrystals into Polymer Nanoparticles 
ACS Nano  2014;8(9):9143-9153.
Nanoparticles of complex architectures can have unique properties. Self-assembly of spherical nanocrystals is a high yielding route to such systems. In this study, we report the self-assembly of a polymer and nanocrystals into aggregates, where the location of the nanocrystals can be controlled to be either at the surface or in the core. These nanospheres, when surface decorated with nanocrystals, resemble disco balls, thus the term nanodisco balls. We studied the mechanism of this surface loading phenomenon and found it to be Ca2+ dependent. We also investigated whether excess phospholipids could prevent nanocrystal adherence. We found surface loading to occur with a variety of nanocrystal types including iron oxide nanoparticles, quantum dots, and nanophosphors, as well as sizes (10–30 nm) and shapes. Additionally, surface loading occurred over a range of polymer molecular weights (∼30–3000 kDa) and phospholipid carbon tail length. We also show that nanocrystals remain diagnostically active after loading onto the polymer nanospheres, i.e., providing contrast in the case of magnetic resonance imaging for iron oxide nanoparticles and fluorescence for quantum dots. Last, we demonstrated that a fluorescently labeled protein model drug can be delivered by surface loaded nanospheres. We present a platform for contrast media delivery, with the unusual feature that the payload can be controllably localized to the core or the surface.
doi:10.1021/nn502730q
PMCID: PMC4174093  PMID: 25188401
directed assembly; nanoparticles; polyphosphazene; MRI; multimodal; theranostic
15.  Facile Method for the Site-Specific, Covalent Attachment of full-length IgG onto Nanoparticles 
Antibodies, most commonly IgGs, have been widely used as targeting ligands in research and therapeutic applications due to their wide array of targets, high specificity and proven efficacy. Many of these applications require antibodies to be conjugated onto surfaces (e.g. nanoparticles and microplates); however, most conventional bioconjugation techniques exhibit low crosslinking efficiencies, reduced functionality due to non-site-specific labeling and random surface orientation, and/or require protein engineering (e.g. cysteine handles), which can be technically challenging. To overcome these limitations, we have recombinantly expressed Protein Z, which binds the Fc region of IgG, with an UV active non-natural amino acid benzoylphenyalanine (BPA) within its binding domain. Upon exposure to long wavelength UV light, the BPA is activated and forms a covalent link between the Protein Z and the bound Fc region of IgG. This technology was combined with expressed protein ligation (EPL), which allowed for the introduction of a fluorophore and click chemistry-compatible azide group onto the C-terminus of Protein Z during the recombinant protein purification step. This enabled crosslinked-Protein Z-IgG complexes to be efficiently and site-specifically attached to aza-dibenzycyclooctyne-modified nanoparticles, via copper-free click chemistry.
doi:10.1002/smll.201303629
PMCID: PMC4142076  PMID: 24729432
Antibody; conjugation; site-specific; click chemistry; nanoparticle
16.  Optimization of Photoactive Protein Z for Fast and Efficient Site-Specific Conjugation of Native IgG 
Bioconjugate Chemistry  2014;25(9):1709-1719.
Antibody conjugates have been used in a variety of applications from immunoassays to drug conjugates. However, it is becoming increasingly clear that in order to maximize an antibody’s antigen binding ability and to produce homogeneous antibody-conjugates, the conjugated molecule should be attached onto IgG site-specifically. We previously developed a facile method for the site-specific modification of full length, native IgGs by engineering a recombinant Protein Z that forms a covalent link to the Fc domain of IgG upon exposure to long wavelength UV light. To further improve the efficiency of Protein Z production and IgG conjugation, we constructed a panel of 13 different Protein Z variants with the UV-active amino acid benzoylphenylalanine (BPA) in different locations. By using this panel of Protein Z to cross-link a range of IgGs from different hosts, including human, mouse, and rat, we discovered two previously unknown Protein Z variants, L17BPA and K35BPA, that are capable of cross-linking many commonly used IgG isotypes with efficiencies ranging from 60% to 95% after only 1 h of UV exposure. When compared to existing site-specific methods, which often require cloning or enzymatic reactions, the Protein Z-based method described here, utilizing the L17BPA, K35BPA, and the previously described Q32BPA variants, represents a vastly more accessible and efficient approach that is compatible with nearly all native IgGs, thus making site-specific conjugation more accessible to the general research community.
doi:10.1021/bc500305v
PMCID: PMC4166039  PMID: 25121619
17.  Assessment of global cardiac uptake of Radiolabeled Iron Oxide Nanoparticles in Apolipoprotein E-Deficient Mice: implications for imaging cardiovascular inflammation 
Purpose
Atherosclerosis is a leading cause of death in industrialized countries and is characterized by the accumulation of lipids and inflammatory cells, including macrophages, in blood vessel walls. Therefore, the ability to image macrophages could help identify plaques that are precursors of acute thrombotic events. Previous research has shown that long-circulating, nanoparticles could be used to detect macrophages within atherosclerotic plaques of the aorta. By conducting this study, we investigated whether global cardiac uptake of radiolabeled nanoparticles could allow assessment of total macrophage burden in the coronary arteries.
Procedures
Dextran-coated Iron Oxide Nanoparticles (IONPs) were labeled with iodine-125 via Bolton-Hunter (SHPP) method. IONPs were characterized by means of dynamic light scattering and transmission electronic microscopy. Biodistribution studies were performed in healthy and atherosclerotic mice. Additionally, digital autoradiography of hearts from both healthy and atherosclerotic mice was performed to assess regional and global atherosclerotic burden.
Results
The [125I]IONPs exhibited high radiolabel stability and long blood circulation, which eventually led to high heart uptake in apoE −/− mice when compared with healthy controls. Furthermore, digital autoradiography showed substantially enhanced emission of signals from the hearts of atherosclerotic mice, while no or minimal cardiac signals were detected in healthy mice.
Conclusions
This preparation showed adequate physical-chemical properties for in vivo studies, such as small size (~30 nm), good radiolabel stability, and long circulation time. There was also significant accumulation in the heart of apoE−/− mice compared with that of healthy control animals. These findings suggest that radiolabeled dextran-coated iron oxide nanoparticles may have potential to become a useful tool to detect macrophages in the atherosclerosis plaques of coronary arteries; however, these preliminary findings should be confirmed by further studies in a larger scale in various atherosclerosis models.
doi:10.1007/s11307-013-0709-9
PMCID: PMC4016162  PMID: 24297372
Atherosclerosis; Radiolabeled nanoparticles; Diagnosis; Iron oxide nanoparticles; Global heart uptake
18.  Stabilized porous liposomes with encapsulated Gd-labeled dextran as highly efficient MRI contrast agents 
A highly efficient contrast agent for magnetic resonance imaging was developed by encapsulating gadolinium within a stabilized porous liposome. The highly porous membrane leads to a high relaxivity of the encapsulated Gd. The stability of the liposome was improved by forming a polymer network within the bilayer membrane.
doi:10.1039/c3cc48939f
PMCID: PMC3947407  PMID: 24457826
19.  A Multifunctional Nanoplatform for Imaging, Radiotherapy, and the Prediction of Therapeutic Response 
Gold nanoparticles have garnered interest as both radiosensitzers and computed tomography (CT) contrast agents. However, the extremely high concentrations of gold required to generate CT contrast is far beyond that needed for meaningful radiosensitization, which limits their use as combined therapeutic–diagnostic (theranostic) agents. To establish a theranostic nanoplatform with well-aligned radiotherapeutic and diagnostic properties for better integration into standard radiation therapy practice, a gold- and superparamagnetic iron oxide nanoparticle (SPION)-loaded micelle (GSM) is developed. Intravenous injection of GSMs into tumor-bearing mice led to selective tumoral accumulation, enabling magnetic resonance (MR) imaging of tumor margins. Subsequent irradiation leads to a 90-day survival of 71% in GSM-treated mice, compared with 25% for irradiation-only mice. Furthermore, measurements of the GSM-enhanced MR contrast are highly predictive of tumor response. Therefore, GSMs may not only guide and enhance the efficacy of radiation therapy, but may allow patients to be managed more effectively.
doi:10.1002/smll.201401927
PMCID: PMC4329028  PMID: 25264301
20.  Gold nanoparticles in radiation research: potential applications for imaging and radiosensitization 
Translational cancer research  2013;2(4):280-291.
The potential of gold nanoparticles (GNPs) in therapeutic and diagnostic cancer applications is becoming increasingly recognized. These biologically compatible particles can be easily synthesized, tuned to different sizes, and functionalized by conjugation to various biologically useful materials. Efficient and specific delivery to tumor tissue can then be accomplished either by passive accumulation in leaky tumor vessels and tissue, or by directly targeting tumor-specific biomarkers. Tumor-localized GNPs can serve as both adjuvants for enhancing the efficacy of radiation therapy and also as contrast agents for various imaging modalities. In this review, we will discuss recent advancements and future potential in the application of GNP as both a radiosensitizer and an imaging contrast agent. Due to their versatility and biocompatibility, gold nanoparticles may represent a novel theranostic adjuvant for radiation applications in cancer management.
doi:10.3978/j.issn.2218-676X.2013.08.09
PMCID: PMC4241969  PMID: 25429358
Gold Nanoparticle (GNP); theranostics; radiosensitization; nanoscale
21.  Sortase-Tag Expressed Protein Ligation (STEPL): combining protein purification and site-specific bioconjugation into a single step 
Analytical chemistry  2013;85(22):10.1021/ac402871k.
Efficient labeling of protein-based targeting ligands with various cargos (drugs, imaging agents, nanoparticles, etc.) is essential to the fields of molecular imaging and targeted therapeutics. Many common bioconjugation techniques, however, are inefficient, non-stoichiometric, not site-specific, and/or incompatible with certain classes of protein scaffolds. Additionally, these techniques can result in a mixture of conjugated and unconjugated products, which are often difficult to separate. In this study, a bacterial sortase enzyme was utilized to condense targeting ligand purification and site-specific conjugation at the C-terminus into a single step. A model was produced to determine optimal reaction conditions for high conjugate purity and efficient utilization of cargo. As proof-of-principle, the sortase-tag expressed protein ligation (STEPL) technique was used to generate tumor-specific affinity ligands with fluorescent labels and/or azide modifications at high purity (>95%) such that is was not necessary to remove unconjugated impurities. Click chemistry was then used for the highly efficient and site-specific attachment of the azide-modified targeting ligands onto nanoparticles.
doi:10.1021/ac402871k
PMCID: PMC3843242  PMID: 24111659
Sortase; bioconjugation; click chemistry; expressed protein ligation; nanoparticle
22.  Monitoring Phospholipase A2 Activity with Gd-encapsulated Phospholipid Liposomes 
Scientific Reports  2014;4:6958.
To date, numerous analytical methods have been developed to monitor phospholipase A2 (PLA2) activity. However, many of these methods require the use of unnatural PLA2 substrates that may alter enzyme kinetics, and probes that cannot be extended to applications in more complex environments. It would be desirable to develop a versatile assay that monitors PLA2 activity based on interactions with natural phospholipids in complex biological samples. Here, we developed an activatable T1 magnetic resonance (MR) imaging contrast agent to monitor PLA2 activity. Specifically, the clinically approved gadolinium (Gd)-based MR contrast agent, gadoteridol, was encapsulated within nanometer-sized phospholipid liposomes. The encapsulated Gd exhibited a low T1-weighted signal, due to low membrane permeability. However, when the phospholipids within the liposomal membrane were hydrolyzed by PLA2, encapsulated Gd was released into bulk solution, resulting in a measureable change in the T1-relaxation time. These activatable MR contrast agents can potentially be used as nanosensors for monitoring of PLA2 activity in biological samples with minimal sample preparation.
doi:10.1038/srep06958
PMCID: PMC4223643  PMID: 25376186
23.  Gd-labeled glycol chitosan as a pH-responsive magnetic resonance imaging agent for detecting acidic tumor microenvironments 
Journal of medicinal chemistry  2013;56(20):10.1021/jm4012565.
Neoplastic lesions can create a hostile tumor microenvironment with low extracellular pH. It is commonly believed that these conditions can contribute to tumor progression and resistance to therapy. We report the development and characterization of a pH-responsive magnetic resonance imaging contrast agent, for imaging the acidic tumor microenvironment. The preparation included conjugation of 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid 1-(2,5-dioxo-1-pyrrolidinyl) ester (DOTA-NHS) to the surface of a water soluble glycol chitosan (GC) polymer, which contains pH titrable primary amines, followed by gadolinium complexation (GC-NH2-GdDOTA). GC-NH2-GdDOTA had a chelate to polymer ratio of approximately1:24 and a molar relaxivity of 9.1 mM−1s−1. GC-NH2-GdDOTA demonstrated pH-dependent cellular association in vitro compared to the control. It also generated a 2.4-fold enhancement in signal in tumor bearing mice 2 h post-injection. These findings suggest that glycol chitosan coupled with contrast agents can provide important diagnostic information about the tumor microenvironment.
doi:10.1021/jm4012565
PMCID: PMC3880625  PMID: 24044414
24.  Quantitative Comparison of Tumor Delivery for Multiple Targeted Nanoparticles Simultaneously by Multiplex ICP-MS 
Scientific Reports  2014;4:5840.
Given the rapidly expanding library of disease biomarkers and targeting agents, the number of unique targeted nanoparticles is growing exponentially. The high variability and expense of animal testing often makes it unfeasible to examine this large number of nanoparticles in vivo. This often leads to the investigation of a single formulation that performed best in vitro. However, nanoparticle performance in vivo depends on many variables, many of which cannot be adequately assessed with cell-based assays. To address this issue, we developed a lanthanide-doped nanoparticle method that allows quantitative comparison of multiple targeted nanoparticles simultaneously. Specifically, superparamagnetic iron oxide (SPIO) nanoparticles with different targeting ligands were created, each with a unique lanthanide dopant. Following the simultaneous injection of the various SPIO compositions into tumor-bearing mice, inductively coupled plasma mass spectroscopy was used to quantitatively and orthogonally assess the concentration of each SPIO composition in serial blood and resected tumor samples.
doi:10.1038/srep05840
PMCID: PMC4894420  PMID: 25068300
25.  Effect of ligand density, receptor density, and nanoparticle size on cell targeting 
It is generally accepted that the presentation of multiple ligands on a nanoparticle surface can improve cell targeting; however, little work has been done to determine whether an optimal ligand density exists. We have recently developed a site-specific bioconjugation strategy that allows for distinct control of ligand density on a nanoparticle through the combined utilization of expressed protein ligation (EPL) and copper-free click chemistry. This EPL-Click conjugation strategy was applied to create superparamagnetic iron oxide (SPIO) nanoparticles labeled with HER2/neu targeting affibodies at differing ligand densities. It was discovered that an intermediate ligand density provided statistically significant improvements in cell binding compared with higher and lower ligand densities. This intermediate optimal ligand density was conserved across nanoparticles with differing hydrodynamic diameters, different HER2/neu targeting ligands and also to cells with lower receptor densities. Additionally, an intermediate optimal ligand density was also evident when nanoparticles were labeled with folic acid.
doi:10.1016/j.nano.2012.05.015
PMCID: PMC3502720  PMID: 22687896
Ligand Density; SPIO; Targeting; Click Chemistry; nanoparticle

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