Shantikumar V Nair

Amrita Institute of Medical Sciences, Fort Cochin, Kerala, India

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Publications (150)529.12 Total impact

  • Handbook of Clinical Nanomedicine: From Bench to Bedside, 01/2015; Pan Stanford Publishing., ISBN: 978-9814316170
  • Journal of Biomedical Nanotechnology 01/2015; 11(1):93-104. · 7.58 Impact Factor
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    ABSTRACT: The electrochemical flow capacitor (EFC) plays an important role in the energy storage field. The potential and ease of large scale energy storage of an EFC makes it highly adaptable for grid-scale energy storage. Current working models for an EFC operate with activated carbon and other coarse-sized carbon-based materials as the input slurry material with limited device performance. Graphene, which has a large specific surface area and also offers the advantage of being in the nano-carbon form, is an excellent candidate for energy storage. In this paper, we investigate the efficiency enhancement of an EFC device when a graphene nanoplatelets-ionic electrolyte was used as the input slurry material for the flow device and charged–discharged; moreover, we have compared it with the coarse and conventional graphite-aqueous electrolyte slurry. The performance evaluation of a newly developed composition of graphene-based slurry with high capacitance was carried out and this slurry was used as both static and dynamic energy storage device. Thin film layers coated with this slurry have a high electrode specific capacitance greater than 300 F g À1 , low-cost and a nickel-free composition with relatively low toxicity. The intermittent flow device has shown a device capacitance of 64.5 F with 2 V and a 5 mL graphene slurry input, which corresponds to an energy density of 14.3 W h L À1 . The device with a graphite slurry has shown a capacitance of 2.3 F with 1.6 V and an energy density of 0.422 W h L À1 . When the graphene nanoplatelets-based slurry was used in the actual EFC full flow device, it gives a capacitance of 1.08 F, 2 V device performance with a slurry input of 24 mL. Moreover, the graphene nanoplatelets-based slurry when used together with the ionic electrolyte shows a better device EFC performance (i.e. an energy density of 6 W h kg À1 (0.064 W h L À1)) when compared to using a coarse graphite-based slurry (device capacitance of 0.75 F with 1.6 V, and an energy density of 2.2 W h kg À1 (0.026 W h L À1)). Thus, this proof-of-concept study gives a significant difference in performance between a graphene slurry-based device and the conventional graphite slurry-based device. This model can be extended further by slurry material modification (such as the addition of materials displaying faradaic capacitance) to realize better performing flow-based devices.
    Journal of Materials Chemistry A: Materials for Energy and Sustainability 12/2014;
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    ABSTRACT: Nanosurface engineering of metallic substrates for improved cellular response is a persistent theme in biomaterials research. The need to improve the long term prognosis of commercially available stents has led us to adopt a 'polymer-free' approach which is cost effective and industrially scalable. In this study, 316L stainless steel substrates were surface modified by hydrothermal treatment in alkaline pH, with and without the addition of a chromium precursor, to generate a well adherent uniform nanotopography. The modified surfaces showed improved hemocompatibility and augmented endothelialization, while hindering the proliferation of smooth muscle cells. Moreover, they also exhibited superior material properties like corrosion resistance, surface integrity and reduced metal ion leaching. The combination of improved corrosion resistance and selective vascular cell viability provided by nanomodification can be successfully utilized to offer a cell-friendly solution to the inherent limitations pertinent to bare metallic stents.
    Nanoscale 12/2014; · 6.73 Impact Factor
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    ABSTRACT: We have synthesized 3-D flower-like mesostructured TiO 2 from one-dimensional electrospun TiO 2 −SiO 2 nanocomposites through a modified titanate route for dye-sensitized solar cell (DSC) application. The TiO 2 3-D mesoflowers with commendable internal surface area, crystallinity, and a good light scattering property satisfy the prerequisites of a DSC photoanode material. The starting TiO 2 −SiO 2 composite, intermediate titanate, and final 3-D mesoflowered TiO 2 were characterized by spectroscopy, microscopy, and surface area measurements. A DSC employing 3-D mesoflowered TiO 2 as the photoanode showed a power conversion efficiency of 8.3% which was 23% higher than that of commercial P-25 (6.37%). KEYWORDS: Dye-sensitized solar cell, TiO 2 , TiO 2 −SiO 2 composite, Light scattering, Electrochemical impedance spectroscopy ■ INTRODUCTION TiO 2 is a material for multifaceted applications in areas such as dye-sensitized solar cells (DSCs), storage devices, photonic crystals, self-cleaning coatings, environmental remediation, water purification, etc. 1−9 DSCs, first presented by O'Regan and Grä tzel in 1991, marked a paradigm shift in the area of renewable energy research. 10 DSC is still considered as one of the options for harnessing solar energy as it employs environmentally benign and relatively cheap raw materials for its making in addition to fabrication feasibilities under nonvacuum conditions. TiO 2 forms the backbone of DSCs as it performs the dual functions of supporting the sensitizers (the dyes) and charge transport. Sensitizer loading on TiO 2 is directly related to its density, surface area, and phase purity, and smooth charge transport is a measure of its crystallinity. Thus, fabrication of dense, crystalline, and high surface area TiO 2 is essential to have efficient DSC devices. Many researchers have investigated the usefulness of electro-spun TiO 2 nanofibers for DSCs but ended up with a lower efficiency in the range of 4−5% in lab-scale research. 11−15
    ACS Sustainable Chemistry and Engineering. 12/2014; 2(12):2772–2780.
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    ABSTRACT: The field of molecular detection and targeted imaging has evolved considerably with the introduction of fluorescent semiconductor nanocrystals. Manganese-doped zinc sulphide nanocrystals (ZnS:Mn NCs), which are widely used in electroluminescent displays, have been explored for the first time for direct immunofluorescent (IF) labeling of clinical tumor tissues. ZnS:Mn NCs developed through a facile wet chemistry route were capped using amino acid cysteine, conjugated to streptavidin and thereafter coupled to biotinylated epidermal growth factor receptor (EGFR) antibody utilizing the streptavidin–biotin linkage. The overall conjugation yielded stable EGFR antibody conjugated ZnS:Mn NCs (EGFR ZnS:Mn NCs) with a hydrodynamic diameter of 65 ± 15 nm, and having an intense orange–red fluorescence emission at 598 nm. Specific labeling of EGF receptors on EGFR+ve A431 cells in a co-culture with EGFR−ve NIH3T3 cells was demonstrated using these nanoprobes. The primary antibody conjugated fluorescent NCs could also clearly delineate EGFR over-expressing cells on clinical tumor tissues processed by formalin fixation as well as cryopreservation with a specificity of 86% and accuracy of 88%, in comparison to immunohistochemistry. Tumor tissues labeled with EGFR ZnS:Mn NCs showed good fluorescence emission when imaged after storage even at 15 months. Thus, ZnS nanobioconjugates with dopant-dependent and stable fluorescence emission show promise as an efficient, target-specific fluorophore that would enable long term IF labeling of any antigen of interest on clinical tissues.
    Nanotechnology 11/2014; 25(44). · 3.84 Impact Factor
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    ABSTRACT: Metformin, a biguanide, is a commonly administered drug for the management of type 2 diabetes mellitus. The drug received a lot of recognition, when retrospective studies proved metformin-associated reduction in cancer risk. Metformin has potential anti cancer effects and an ability to suppress tumor growth both in vitro and in vivo. Activation of LKB1/AMPK pathway and cancer stem destruction along with cell cycle arrest and apoptosis induction is the proposed mechanisms of anti cancer potential of metformin. Nanotechnology approaches have also been adopted for metformin delivery to cancer cells. This review directs on the application of metformin for the therapy of various cancers and also the different pathways responsible for the metformin derived anti cancer effect. It also focuses on the pharmacological applications of the drug and the nanotechnology approaches for metformin delivery.
    Current Cancer Drug Targets 10/2014; · 4.00 Impact Factor
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    Prathapan Ragesh, Shantikumar V Nair, A Sreekumaran Nair
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    ABSTRACT: Fluorinated POSS (polyhedral oligomeric silsesquioxanes, F-POSS) was blended with PVDF (poly (vinylidene fluoride)/TiO 2 (titanium dioxide) composite by stirring overnight and the resultant solution was electrospun to obtain F-POSS/PVDF/TiO 2 micron-and nanofibers with self-cleaning capacity. The coatings were deposited on a fluorosilane-treated glass substrate and they showed both hydrophobicity and photocatalytic activity. The morphology of the fabricated coating was analysed using scanning electron microscopy and atomic force microscopy. The optical properties of the coating were studied using UV-visible spectroscopy, which gave around 65–70% transmittance with just 2% of F-POSS inclusion. Membrane stability on the substrate was checked with the nano-scratch test. The nano-scratch test indicates that the tip of the nano-indenter was unable to percolate through the membrane; rather it just ploughs around its surface, revealing the adhesion of coating and mechanical stability. The contact angle measurements showed a value of 135.5 for the F-POSS/PVDF/TiO 2 coating, thus showing its hydrophobic nature. The photocatalytic effect of the membrane was checked with respect to the degradation of methyl orange dye under UV exposure. The surface roughness calculated from the AFM measurements showed that the inclusion of F-POSS into the nanofibers enhanced the surface roughness. We anticipate that the thermally and mechanically stable coating may find immense applications in many real areas like water-purification, window panels, glass modules for photovoltaic devices, etc.
    RSC Advances 08/2014; 4:2014. · 3.71 Impact Factor
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    ABSTRACT: We outline a simple protocol for fabricating high surface area ($86 m 2 g À1) TiO 2 nanoparticles via freeze-drying of a composite of a TiO 2 precursor ((Ti(IV) isopropoxide)) and a polymer (polyester) solution. The composite upon freeze-drying results in a porous mass which on subsequent sintering results in degradation of the polymer and formation of TiO 2 nanoparticles. The TiO 2 particles when employed as a photoanode of dye-sensitized solar cells show an efficiency (h) of $7%. TiO 2 is a wide band-gap metal oxide semiconductor which is best known for its photovoltaic (dye-sensitized solar cells, DSCs), photocatalytic, self-cleaning, environmental remedia-tion, etc. properties. 1–3 DSCs, because of the low cost of the components involved, their exibility and environmentally friendly nature, remain as one of the most promising photo-voltaic technologies and continue to draw a great deal of research attention. 4 TiO 2 serves as the backbone of DSC which does the dual role of supporting the sensitizers as well as facilitating electron transport back to the transparent con-ducting oxide. 5,6 TiO 2 with high surface area and high porosity is essential in DSC for efficient dye adsorption and fast movement of electrolyte ions in and out of the system. 7–10 There are several routes available for the synthesis of TiO 2 nanoparticles, the prominent being sol–gel, hydrothermal, template-assisted, electrospinning, etc. 2b,11 Commercially avail-able TiO 2 is P-25 (from Degussa) which possess a surface area of $40 m 2 g À1 . There are high surface area TiO 2 available in the market (such as Ishihara ST01 12,13 and Hombikat UV100 (ref. 14 and 15)) but are expensive. Electrospinning is a facile approach for making metal oxide nanobers; however, the bers usually have large diameter distributions ($100 nm to $500 nm) and have low surface areas ($44 m 2 g À1) and fewer yields. 16,17 The surface areas of electrospun TiO 2 could be enhanced further through post-treatments, 18 however, this is a two-step approach and expensive. In such a scenario, we thought of devising a simple protocol by which high surface area TiO 2 could be produced for the above mentioned applications. Thus, the present work outlines a simple protocol for getting high surface area mesoporous anatase TiO 2 for DSC applica-tions. Titanium(IV) isopropoxide (TIP) was dissolved in a solu-tion of polyester (which is characterized by the presence of a
    RSC Advances 08/2014; 4:36821. · 3.71 Impact Factor
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    ABSTRACT: This review article exemplifies the importance of self-cleaning materials and coatings. Self-cleaning coatings are becoming an integral part of our daily life because of their utility in various applications such as windows, solar panels, cements, and paints. In this review, various categories of materials for the fabrication of hydrophilic, hydrophobic, oleophobic, amphiphobic and multifunctional coatings and their synthesis routes have been discussed. Furthermore, different natural organisms exhibiting superhydrophobic behaviour have been analysed. This review also covers the fundamentals of self-cleaning attributes such as water contact angle, surface energy, and contact angle hysteresis.
    Journal of Materials Chemistry A: Materials for Energy and Sustainability 08/2014; 2:14773-14797.
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    ABSTRACT: The present study demonstrates a novel, low temperature synthesis approach by which 3-D bouquets of nickel hydroxide nitrate were processed into high surface area electrodes for supercapacitor applications. The synthesized micro-bouquets comprised of randomly arrayed microporous nanoflakes (pore size: 2−6 nm) and exhibited a surface area of 150 m2g-1. Morphological evolution studies were done to elucidate how surface morphology of these electrode materials affect the redox reactions and hence the ultimate performance of the supercapacitor. The electrodes were tested in three different electrolytes namely lithium hydroxide, potassium hydroxide and sodium hydroxide. From the detailed electrochemical analysis, an intrinsic correlation between the capacitance, internal resistance and the surface morphology was deduced and explained on the basis of relative contributions from the faradaic properties in different electrolytes. Depending on the surface morphology and electrolyte incorporated, these nano/micro-hybrid electrodes exhibited specific mass capacitance value as high as 1380±38 Fg-1. Inductively coupled plasma-atomic emission spectroscopy was used to determine the electrode dissolution in the given electrolyte and the findings were co-related with the cycling stability. By employing this low cost electrode design, high stability (> 5000 cycles with no fading) was attained in lithium hydroxide electrolyte. Further, a working model supercapacitor in coin cell form is also shown exhibiting peak power and energy density of 3 kWkg-1 and 800 mWhkg-1 respectively.
    RSC Advances 08/2014; · 3.71 Impact Factor
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    ABSTRACT: Migratory capacity of cancer plays a critical role in the process of metastasis. Aberrant focal adhesions activated by the phosphorylation of Src kinase enables cancer cells to anchor on its micro-environment and migrate towards biochemically favorable niche, causing metastasis. Effective blocking of the migratory capacity of cancer cells by inhibiting protein kinases and subsequent application of cytotoxic stress may provide better therapeutic outcome. Here, we report a novel core-shell nanomedicine that inhibits cancer migration by nano-shell and impart reactive oxygen stress by laser assisted photosensitization of nano-core. For this, we have optimized a polymer-protein nanoconstruct where a photosensitizer (5,10,15,20-tetrakis(meso-hydroxyphenyl)porphyrin (mTHPP) is loaded into poly(lactic-co-glycolic acid) (PLGA) nano-core and Src kinase inhibitor (dasatinib) is loaded into albumin nano-shell. The polymer-core was prepared by electrospray technique and albumin-shell was formed by alcohol coacervation. Transmission electron microscopy studies revealed the formation of ~80 nm sized nano-core decorated with ~10 nm size nano-shell. Successful incorporation of monomeric mTHPP in nano-core resulted improved photo-physical properties and singlet oxygen release under physiological conditions compared to free-mTHPP. Core-shell nanomedicine also showed dose and time dependent cellular uptake in U87MG glioma cells. Dasatinib released from nano-shell caused down regulation of phospho-Src leading to significant impairment of cancer migration and subsequent laser assisted photosensitization of nano-core resulted in the release of reactive oxygen stress leading to apoptosis of spatially confined cancer cells. In vivo studies on Wistar rats indicated the absence of any significant toxicity caused by the intravenous administration of nanomedicine. These results clearly show the advantage of core-shell nanomedicine mediated combinatorial approach for inhibiting important cancer signalling pathways togother with imparting cytotoxic stress.
    Journal of Biomedical Nanotechnology 08/2014; 10(8):1401-1415. · 7.58 Impact Factor
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    ABSTRACT: This review article exemplifies the importance of self-cleaning materials and coatings. Self-cleaning coatings are becoming an integral part of our daily life because of their utility in various applications such as windows, solar panels, cements, and paints. In this review, various categories of materials for the fabrication of hydrophilic, hydrophobic, oleophobic, amphiphobic and multifunctional coatings and their synthesis routes have been discussed. Furthermore, different natural organisms exhibiting superhydrophobic behaviour have been analysed. This review also covers the fundamentals of self-cleaning attributes such as water contact angle, surface energy, and contact angle hysteresis.
    Journal of Materials Chemistry A: Materials for Energy and Sustainability 07/2014;
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    ABSTRACT: We have fabricated ‘cabbage leaf’-like TiO2 mesostructures of high surface area from electrospun TiO2– SiO2 composite nanofibers by titanate route for dye-sensitized solar cell (DSC) application. The initial TiO2–SiO2 composite nanofibers, the intermediate titanate and the final leaf-like TiO2 are characterized by spectroscopy, microscopy and surface area measurements. The material (final TiO2) acts as a dual functional material in DSCs with high dye loading and a high light scattering capability. The best DSC (a square-shaped cell of area 0.20 cm2 and thickness of 12 mm) fabricated out of the material showed a superior photovoltaic performance with an efficiency (h) of 7.92% in comparison to that of commercial P25 TiO2 (6.50%).
    RSC Advances 06/2014; 4:27084. · 3.71 Impact Factor
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    ABSTRACT: Combinatorial drug delivery is an attractive, but challenging requirement of next generation cancer nanomedicines. Here, we report a transferrin-targeted core-shell nanomedicine formed by encapsulating two clinically used single-agent drugs, Doxorubicin and Sorafenib against liver cancer. Doxorubicin was loaded in poly(vinyl alcohol) nano-core and sorafenib in albumin nano-shell, both formed by a sequential freeze-thaw/coacervation method. While sorafenib from the nano-shell inhibited aberrant oncogenic signaling involved in cell proliferation, doxorubicin from the nano-core evoked DNA intercalation thereby killing >75% of cancer cells. Upon targeting using transferrin ligands, the nanoparticles showed enhanced cellular uptake and synergistic cytotoxicity in ~92% of cells, particularly in iron-deficient microenvironment. Studies using 3D spheroids of liver tumor indicated efficient penetration of targeted core-shell nanoparticles throughout the tissue causing uniform cell killing. Thus, we show that rationally designed core-shell nanoparticles can effectively combine clinically relevant single-agent drugs for exerting synergistic activity against liver cancer.
    Nanomedicine : nanotechnology, biology, and medicine. 06/2014;
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    ABSTRACT: Nanoparticles of varying composition, size, shape, and architecture have been explored for use as photothermal agents in the field of cancer nanomedicine. Among them, gold nanoparticles provide a simple platform for thermal ablation owing to its biocompatibility in vivo. However, the synthesis of such gold nanoparticles exhibiting suitable properties for photothermal activity involves cumbersome routes using toxic chemicals as capping agents, which can cause concerns in vivo. Herein, gold nanoparticles, synthesized using green chemistry routes possessing near-infrared (NIR) absorbance facilitating photothermal therapy, would be a viable alternative. In this study, anisotropic gold nanoparticles were synthesized using an aqueous route with cocoa extract which served both as a reducing and stabilizing agent. The as-prepared gold nanoparticles were subjected to density gradient centrifugation to maximize its NIR absorption in the wavelength range of 800-1000 nm. The particles also showed good biocompatibility when tested in vitro using A431, MDA-MB231, L929, and NIH-3T3 cell lines up to concentrations of 200 μg/mL. Cell death induced in epidermoid carcinoma A431 cells upon irradiation with a femtosecond laser at 800 nm at a low power density of 6 W/cm(2) proved the suitability of green synthesized NIR absorbing anisotropic gold nanoparticles for photothermal ablation of cancer cells. These gold nanoparticles also showed good X-ray contrast when tested using computed tomography (CT), proving their feasibility for use as a contrast agent as well. This is the first report on green synthesized anisotropic and cytocompatible gold nanoparticles without any capping agents and their suitability for photothermal therapy.
    ACS Applied Materials & Interfaces 05/2014; · 5.90 Impact Factor
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    ABSTRACT: We report a unique one-dimensional (1-D) morphology of TiO2 having TiO2 nanoparticles decorating the surface of TiO2 nanofibers fabricated by simultaneous electrospinning and electrospraying technique. The composite made by both nanofibers and nanoparticles is used as a photoanode material for dye-sensitized solar cells (DSCs) which helped in overcoming the limitations associated with nanofibers and nanoparticles when employed separately. The DSC showed an excellent efficiency of 7.89% (for a square-shaped cell of area 0.2 cm2) in comparison to 6.87 % for the nanoparticulate DSC and 5.21% for the nanofiber DSC (for cells of same area and thickness) which is an impressive value when literature on DSC fabrication with 1-D nanostructures for DSCs is concerned.
    RSC Advances 05/2014; · 3.71 Impact Factor
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    ABSTRACT: We provide a complete illustration of dye-sensitized solar module fabrication by spray pyrolysis deposition (SPD) of a TiO2 colloid having ~ 10 nm size TiO2 nanoparticles. The process was first optimized for cell level fabrication and the parameters (mainly the thickness) obtained from the study were subsequently used for module level fabrication. The best efficiency obtained in cell level (area 0.2 cm2 and thickness of 12 m) was 7.79 % and that for the (12 cm  12 cm) module was 3.2%.
    RSC Advances 05/2014; · 3.71 Impact Factor
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    ABSTRACT: Non-steroidal anti-inflammatory drugs (NSAIDs), the medication of choice for various ailments are clinically administered at high doses owing to their poor pharmacokinetics, resulting in severe side-effects. In an attempt to address these limitations, two common NSAIDs (aceclofenac and diclofenac sodium), are nanoencapsulated within a water soluble, biodegradable chitosan derivative, viz., O-carboxymethyl chitosan (O-CMC). The nanoformulations prepared by ionotropic gelation had an average hydrodynamic size of ∼250 nm, with high entrapment efficiencies [80% (Aceclofenac) and 95% (Diclofenac)]. The controlled in vitro drug release profiles obtained for the two drug formulations varied with the nature of the drug. In vitro cytotoxicity and anti-inflammatory studies of NSAID nanoformulations proved the compatibility and efficacy of the particles upto a concentration of 1 mg/ml. Thus, our studies prove the feasibility of using water soluble O-CMC as a nanocarrier for the efficient entrapment of drugs with different chemical characteristics.
    Advanced Science, Engineering and Medicine. 05/2014; 6(5):522-530(9).
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    ABSTRACT: In this study, we have reported the incorporation of a multi-modal contrast agent based on hydroxyapatite nanocrystals, within a poly(caprolactone)(PCL) nanofibrous scaffold by electrospinning. The multifunctional hydroxyapatite nanoparticles (MF-nHAp) showed simultaneous contrast enhancement for three major molecular imaging techniques. In this paper, the magnetic resonance (MR) contrast enhancement ability of the MF-nHAp was exploited for the purpose of potentially monitoring as well as influencing tissue regeneration. These MF-nHAp containing PCL scaffolds were engineered in order to enhance the osteogenic potential as well as its MR functionality for their application in bone tissue engineering. The nano-composite scaffolds along with pristine PCL were evaluated physico-chemically and biologically in vitro, in the presence of human mesenchymal stem cells (hMSC). The incorporation of 30-40nm sized MF-nHAp within the nanofibers showed a substantial increase in scaffold strength, protein adsorption, proliferation and osteogenic differentiation of hMSCs along with enhanced MR functionality. This preliminary study was performed to eventually exploit the MR contrast imaging capability of MF-nHAp in nanofibrous scaffolds for real time imaging of the changes in the tissue engineered construct.
    Tissue Engineering Part A 04/2014; · 4.64 Impact Factor

Publication Stats

660 Citations
529.12 Total Impact Points

Institutions

  • 2009–2014
    • Amrita Institute of Medical Sciences
      Fort Cochin, Kerala, India
  • 2008–2014
    • Amrita Vishwa Vidyapeetham
      • Amrita Center for Nanosciences & Molecular Medicine (ACNSMM)
      Koyambattūr, Tamil Nādu, India
  • 2009–2013
    • Amrita Institute of Medical Sciences and Research Centre
      • Center for Nanosciences and Molecular Medicine
      Cochin, Kerala, India