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1.  Polymeric Multilayers that contain Silver Nanoparticles can be Stamped onto Biological Tissues to Provide Antibacterial Activity 
Advanced functional materials  2011;21(10):1863-1873.
We report the design of polyelectrolyte multilayers (PEMs) that can be prefabricated on an elastomeric stamp and mechanically transferred onto biomedically-relevant soft materials, including medical-grade silicone elastomers (E′~450–1500 kPa; E′-elastic modulus) and the dermis of cadaver-skin (E′~200–600 kPa). Whereas initial attempts to stamp PEMs formed from poly(allylamine hydrochloride) and poly(acrylic acid) resulted in minimal transfer onto soft materials, we report that integration of micrometer-sized beads into the PEMs (thicknesses of 6–160 nm) led to their quantitative transfer within 30 seconds of contact at a pressure of ~196 kPa. To demonstrate the utility of this approach, PEMs were impregnated with a range of loadings of silver-nanoparticles and stamped onto the dermis of human cadaver-skin (a wound-simulant) that was subsequently incubated with bacterial cultures. Skin-dermis stamped with PEMs that released 0.25±0.01 μg cm−2 of silver ions caused a 6 log10 reduction in colony forming units of Staphylococcus epidermidis and Pseudomonas aeruginosa within 12 h. Significantly, this level of silver release is below that which is cytotoxic to NIH 3T3 mouse fibroblast cells. Overall, this study describes a general and facile approach for the functionalization of biomaterial surfaces without subjecting them to potentially deleterious processing conditions.
PMCID: PMC4280836  PMID: 25558188
Polymer-multilayers; silver-nanoparticles; microparticles; stamping; wounds
2.  Colloid-in-Liquid Crystal Gels that Respond to Biomolecular Interactions 
This paper advances the design of stimuli-responsive materials based on colloidal particles dispersed in liquid crystals (LCs). Specifically, we report that thin films of colloid-in-liquid crystal (CLC) gels can undergo easily visualized ordering transitions in response to reversible and irreversible (enzymatic) biomolecular interactions occurring at aqueous interfaces of the gels. In particular, we demonstrate that LC ordering transitions can propagate across the entire thickness of the gels. We observe, however, that confinement of the LC to small domains with lateral sizes of ~10 µm does change the nature of the anchoring transitions, as compared to films of pure LC, due to the effects of confinement on the elastic energy stored in the LC. The effects of confinement are also observed to cause the response of individual domains of the LC within the CLC gel to vary significantly from one another, indicating that manipulation of LC domain size and shape can provide the basis of a general and facile method to tune the response of these LC-basedphysical gels to interfacial phenomena. Overall, the results presented in this paper establish that CLC gels offer a promising approach to the preparation of self-supporting, LC-based stimuli-responsive materials.
PMCID: PMC4025930  PMID: 23554243
Stimuli-Responsive Materials; Liquid Crystals; Gels; Colloids; Biomolecular Interfaces
3.  Slow Yogic Breathing Through Right and Left Nostril Influences Sympathovagal Balance, Heart Rate Variability, and Cardiovascular Risks in Young Adults 
Specific nostril breathing is known to influence autonomic functions.
The study was to assess the effects of right nostril breathing (RNB) and left nostril breathing (LNB) on heart rate variability (HRV) and cardiovascular functions.
Material and Methods:
Eighty-five student volunteers were divided into three groups: RNB group (n = 30), LNB group (n = 30), and control group (n = 25). RNB and LNB group subjects practiced right and left nostril breathing, respectively, every day 1 h for 6 weeks. The control group did not practice nostril breathing. Cardiovascular parameters and spectral indices of HRV were recorded before and after 6-week practice of nostril breathing. In RNB and LNB groups, prediction of rate-pressure product (RPP) by low-frequency to high-frequency ratio (LF-HF) of HRV was assessed by bivariate logistic regression.
HRV indices representing sympathetic activity were increased in the RNB group and indices representing parasympathetic activity were increased in LNB group following 6-week nostril breathing. Prediction of LF-HF to RPP, the marker of cardiovascular risks, was more significant (OR 2.65, P = 0.005) in the LNB group compared to the RNB group (OR 1.452, P = 0.016).
Short-term practice of LNB improves vagal tone, increases HRV, and promotes cardiovascular health of medical students. Practice of RNB increases sympathetic tone and could jeopardize cardiovascular health.
PMCID: PMC3978938  PMID: 24741554
Autonomic functions; Cardiovascular risk; Heart rate variability; Nostril breathing; Sympathovagal balance
4.  The use of native chemical functional groups presented by wound beds for the covalent attachment of polymeric microcarriers of bioactive factors 
Biomaterials  2012;34(2):10.1016/j.biomaterials.2012.09.055.
The development of versatile methods that provide spatial and temporal control over the presentation of physical and biochemical cues on wound beds can lead to new therapeutic approaches that expedite wound healing by favorably influencing cellular behaviors. Towards that goal, we report that native chemical functional groups presented by wound beds can be utilized for direct covalent attachment of polymeric microbeads. Specifically, we demonstrated the covalent attachment of maleimide-functionalized and catechol-functionalized microbeads, made of either polystyrene (non-degradable) or poly(lactic-co-glycolic acid) ((PLGA), degradable), to sulfhydryl and amine groups present on porcine dermis used here as an ex vivo model wound bed. A pronounced increase (10–70 fold) in the density and persistence of the covalently reactive microbeads was observed relative to microbeads that adsorb via non-covalent interactions. Complementary characterization of the surface chemistry of the ex vivo wound beds using Raman microspectroscopy provides support for our conclusion that the increased adherence of the maleimide-functionalized beads results from their covalent bond formation with sulfhydryl groups on the wound bed. The attachment of maleimide-functionalized microbeads to wounds created in live wild-type and diabetic mice led to observations of differential immobilization of microbeads on them and were consistent with anticipated differences in the presentation of sulfhydryl groups on the two different wound types. Finally, the incorporation of maleimide-functionalized microbeads in wounds created in wild-type mice did not impair the rate of wound closure relative to an untreated wound. Overall, the results presented in this paper enable a general and facile approach to the engineering of wound beds in which microbeads are covalently immobilized to wound beds. Such immobilized microbeads could be used in future studies to release bioactive factors (e.g., antimicrobial agents or growth factors) and/or introduce topographical cues that promote cell behaviors underlying healing and wound closure.
PMCID: PMC3651840  PMID: 23088838
Wound healing; Wound bed engineering; Microspheres; Dopamine; Catechols; Maleimide; Diabetic wounds; Raman spectroscopy
5.  Bronchoscopic topical steroid instillation in prevention of tracheal stenosis 
Corrosive acid poisoning commonly results in chemical injuries to respiratory and upper gastrointestinal tract. Corrosive mucosal erosion of the larynx and trachea may occur if the patient aspirates acid. We successfully used local anti-inflammatory action of dexamethasone instilled through a fiber-optic bronchoscope for regression of mucosal edema and prevention of subsequent development of stricture in a young female.
PMCID: PMC3927302  PMID: 24574602
Fiberoptic bronchoscopy; steroid instillation; tracheal stenosis
6.  Polymeric Multilayers that Localize the Release of Chlorhexidine from Biologic Wound Dressings 
Biomaterials  2012;33(28):6783-6792.
Biologic wound dressings contain animal-derived components and are susceptible to high infection rates. To address this issue, we report an approach that permits incorporation of non-toxic levels of the small-molecule antiseptic ‘chlorhexidine’ into biologic dressings. The approach relies on the fabrication of polyelectrolyte multilayer (PEMs) films containing poly(allylaminehydrochloride) (PAH), poly(acrylicacid) (PAA), and chlorhexidine acetate (CX) on elastomeric poly(dimethylsiloxane) (PDMS) sheets. The PEMs (20-100 nm thick) are subsequently stamped onto the wound-contact surface of a synthetic biologic dressing, Biobrane, which contains collagen peptides. Chlorhexidine loading in the PEMs was tailored by tuning the number of (CX/PAA) bilayers deposited, providing burst release of up to 0.98±0.06 μg/cm2 of CX over 24 h, followed by zero order release of 0.35±0.04 μg/cm2/day for another week. Although the CX concentrations released were below the reported in vitro cytotoxicity limit (5 μg/mL over 24 h) for human dermal fibroblasts, they killed 4 log10 counts of pathogenic bacteria Staphylococcus aureus in solution. The CX/PEMs could be stamped onto Biobrane with high efficiency to provide CX release kinetics and in-vitro antibacterial activity similar to that on PDMS stamps. In a full-thickness ‘splinted’ dermal wound-model in normal wild-type mice, the CX-functionalized Biobrane showed no decrease in either its adherence to the wound-bed or wound-closure rate over 14 days. The murine wounds topically inoculated with ~105 CFU/cm2 of S. aureus and treated with CX-functionalized Biobrane demonstrated a 3 log10 decrease in the wound's bacterial burden within 3 days, compared to persistent bacterial colonization found in wounds treated with unmodified Biobrane (n=10 mice, p<0.005). Overall, this study presents a promising approach to prevent bacterial colonization in wounds under biologic dressings.
PMCID: PMC3404134  PMID: 22784602
Polyelectrolye multilayers; chlorhexidine; wound; dressing; mice; antimicrobial
7.  Antibacterial Efficacy of Silver-Impregnated Polyelectrolyte Multilayers Immobilized on a Biological Dressing in a Murine Wound Infection Model 
Annals of surgery  2012;256(2):371-377.
To investigate the antibacterial effect of augmenting a biological dressing with polymer films containing silver nanoparticles.
Biological dressings, such as Biobrane, are commonly used for treating partial-thickness wounds and burn injuries. Biological dressings have several advantages over traditional wound dressings. However, as many as 19% of wounds treated with Biobrane become infected, and, once infected, the Biobrane must be removed and a traditional dressing approach should be employed. Silver is a commonly used antimicrobial in wound care products, but current technology uses cytotoxic concentrations of silver in these dressings. We have developed a novel and facile technology that allows immobilization of bioactive molecules on the surfaces of soft materials, demonstrated here by augmentation of Biobrane with nanoparticulate silver. Surfaces modified with nanometer-thick polyelectrolyte multilayers (PEMs) impregnated with silver nanoparticles have been shown previously to result in in vitro antibacterial activity against Staphylococcus epidermidis at loadings of silver that are noncytotoxic.
We demonstrated that silver-impregnated PEMs can be nondestructively immobilized onto the surface of Biobrane (Biobrane-Ag) and determined the in vitro antibacterial activity of Biobrane-Ag with Staphylococcus aureus. In this study, we used an in vivo wound infection model in mice induced by topical inoculation of S aureus onto full-thickness 6-mm diameter wounds. After 72 hours, bacterial quantification was performed.
Wounds treated with Biobrane-Ag had significantly (P < 0.001) fewer colony-forming units than wounds treated with unmodified Biobrane (more than 4 log10 difference).
The results of our study indicate that immobilizing silver-impregnated PEMs on the wound-contact surface of Biobrane significantly reduces bacterial bioburden in full-thickness murine skin wounds. Further research will investigate whether this construct can be considered for human use.
PMCID: PMC3433034  PMID: 22609841
biological dressing; Biobrane; silver nanoparticles; polyelectrolyte multilayers; infection; chronic wound; murine
8.  The future of anaesthesiology 
Indian Journal of Anaesthesia  2012;56(6):524-528.
There was an era when bark of mandrake plant, boiled in wine was used to administer anesthesia. Ether, after reigning the kingdom of anaesthesiology for more than a century, came to be superseded by newer and newer agents. Anaesthesiology has witnessed tremendous developments since infancy. The introduction of advanced airway adjuncts, labour analgesia, patient controlled analgesia, fibreoptics, Bispectral Index monitors, workstations, simulators and robotic surgeries are only to name a further few. Anaesthesia for robotic surgery received much impetus and is still a dream to come true in many countries. But then, the rapid spin in technology and fast sophistication of medical field has even surpassed this. The next event to venture is entry of robots into human body made possible by a culmination of intricate medicine and fine technology that is Nanotechnology. This article briefly introduces the field of nanotechnology in relation to its potential benefits to the field of anaesthesiology. As with any new tecnique or application, nanotechnology as applied to anaesthesiology has tremendous potential for research and exploration. This article therefore orients the reader's mind towards the immense potential and benefits that can be tapped by carrying out further studies and experimentations.The literature was searched using databases, peer reviewed journals and books for over a period of one year (till December 2011). The search was carried out using keywords as nanotechnology, robotics, anesthesiology etc. Initially a master database was formed including human as well as animal studies. Later on the broad topic area was narrowed down to developments in nanotechnology as applied to anesthesiology. Further filtering of search results were done based on selection of researches and developments relating to local, regional and general anesthesia as well as critical care and pain and palliative care.
PMCID: PMC3546237  PMID: 23325935
Anaesthesiology; future; nanotechnology; robotics
11.  Is Fibreoptic Percutaneous Tracheostomy in ICU A Breakthrough 
In ICUs, bedside percutaneous tracheostomy (pct) is commonly performed, but it is associated with certain drawbacks as paratracheal placement, posterior tracheal wall injury and tracheoesophageal fistula. To address these fibreoptic bronchoscope (FOB) guided PCT was introduced. We aimed to compare both these methods.
Patients & Methods:
We compared 60 age & sex matched patients into two groups of 30 each. In group 1 tracheostomy was performed by the conventional Ciaglia's method. In group 2, a fibreoptic bronchoscope was used in addition with the aid of an assistant.
The fiberoptic method took more time than the conventional method. (18±3min vs 15±2min (p=0.001)). The average no. of attempts at insertion of needle was 2.4 in group 1 and 1.2 in group 2 (p=0.001). The fall in SpO2 to <90% was seen in 1 patient in group 1 and in 6 patients in group 2, so much so that the procedure had to be abandoned in 2 patients.
FOB though definitely advantageous over CPCT in terms of lesser complications and being highly useful in the obese, short necked, and those with scar marks, is not without drawbacks such as requirement of additional staff and increased expenditure. The main being inability to be used in patients with low respiratory reserve. Overall it would be complimentary for any ICU to have FOB facility and must be used in select group of patients.
PMCID: PMC3087259  PMID: 21547181
12.  Non-conventional emergency airway management 
Clinics  2010;65(8):815.
PMCID: PMC2933121  PMID: 20835561
13.  Comparison of Midazolam and Propofol for BIS-Guided Sedation During Regional Anaesthesia 
Indian Journal of Anaesthesia  2009;53(6):662-666.
Regional anaesthesia has become an important anaesthetic technique. Effective sedation is an essential for regional techniques too. This study compares midazolam and propofol in terms of onset & recovery from sedation, dosage and side effects of both the drugs using Bispectral Index monitoring. Ninety eight patients were randomly divided into two groups,one group recieved midazolam infusion while the other recieved propofol infusion until BIS reached 75. We observed Time to reach desired sedation, HR, MABP, time for recovery, dose to reach sedation and for maintenance of sedation and side effects if any. The time to reach required sedation was 11 min in Midazolam group(Group I) while it was 6 min in Propofol group(Group II) (p=0.0). Fall in MABP was greater with propofol. Recovery in with midazolam was slower than with propofol (18.6 ± 6.5 vs 10.10±3.65 min) (p=0.00). We concluded that both midazolam and propofol are effective sedatives, but onset and offset was quicker with propofol, while midazolam was more cardiostable.
PMCID: PMC2900075  PMID: 20640093
Propofol; Midazolam; Sedation; BIS
14.  Ultrasonography: A novel approach to central venous cannulation 
Portable ultrasound machines are highly valuable in ICUs, where a patient's condition might not permit shifting the patient to the USG department for imaging. Traditionally central lines are put blindly using anatomical landmarks, which often result in complications such as difficulty in access, misplaced lines, pneumothorax, bleeding from inadvertent arterial punctures, etc. Ultrasonography provides “real time” imaging, i.e., the needle can be visualized entering the vein.
We performed a study to compare USG guided central venous cannulation (CVC) and conventional anatomical landmark approach to CVC, in terms of ease of cannulation, time consumed, and associated complications.
Settings and Design:
The study was performed in a 16-bed open ICU. Eighty patients were randomly divided in two groups.
Materials and Methods:
The right internal jugular vein (IJV) was cannulated in all. In Group I, a portable ultrasound machine was used during cannulation. The vessels were visualized in the transverse section with the internal carotid artery (ICA) identified as a circular pulsatile structure, while the IJV as a lateral, oval nonpulsatile structure). The needle was inserted perpendicular to the skin under visualization on the US screen. Central venous line was then inserted by the Seldinger technique. In Group II, CVC was performed by the conventional landmark approach. The parameters studied included time for insertion, attempts required, and complications encountered.
Statistical Analysis:
The database of all parameters was analyzed using SPSS software version 10.5.
The mean time to successful insertion was 145 and 176.4 sec in groups I and II, respectively (p = 0.00). An average of 1.2 attempts per cannulation was required for group I, while 1.53 for group II (p = 0.03): 10% witnessed arterial puncture and 2.5% pneumothorax in group I and none in group II.
USG-guided CVC is thus easier, quicker, and safer than landmark approach.
PMCID: PMC2856149  PMID: 20436690
central venous cannulation; intensive care unit; ultrasound

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