Browsing by Author "Victor, SP"

Now showing 1 - 19 of 19
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    Bioactive, mechanically favorable and biodegradable copolymer nanocomposites for orthopedic applications
    (J. of Mater. Sci and Engg, 2014-06) Victor, SP; Jayabalan, M
    We report the synthesis of mechanically favorable, bioactive, and biodegradable copolymer nanocomposites for potential bone applications. The nanocomposites consist of in situ polymerized biodegradable copolyester with hydroxyapatite (HA). Biodegradable copolyesters comprise carboxy terminated poly(propylene fumarate) (CT-PPF) and poly(trimethylol propane fumarate co mannitol sebacate) (TF-Co-MS). Raman spectral imaging clearly reveals a uniform homogenous distribution of HA in the copolymer matrix. The mechanical studies reveal that improved mechanical properties formed when crosslinked with methyl methacrylate (MMA) when compared to N-vinyl pyrrolidone (NVP). The SEM micrographs of the copolymer nanocomposites reveal a serrated structure reflecting higher mechanical strength, good dispersion, and good interfacial bonding of HA in the polymer matrix. In vitro degradation of the copolymer crosslinked with MMA is relatively more than that of NVP and the degradation decreases with an increase in the amount of the HA filler. The mechanically favorable and degradable MMA based nanocomposites also have favorable bioactivity, blood compatibility, cytocompatibility and cell adhesion. The present nanocomposite is a more promising material for orthopedic applications.
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    Bioactive, mechanically favorable, and biodegradable copolymer nanocomposites for orthopedic applications
    (MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS, 2014) Victor, SP; Muthu, J
    We report the synthesis of mechanically favorable, bioactive, and biodegradable copolymer nanocomposites for potential bone applications. The nanocomposites consist of in situ polymerized biodegradable copolyester with hydroxyapatite (HA). Biodegradable copolyesters comprise carboxy terminated poly(propylene fumarate) (CT-PPF) and poly(trimethylol propane fumarate co mannitol sebacate) (TF-Co-MS). Raman spectral imaging clearly reveals a uniform homogenous distribution of HA in the copolymer matrix. The mechanical studies reveal that improved mechanical properties formed when crosslinked with methyl methacrylate (MMA) when compared to N-vinyl pyrrolidone (NVP). The SEM micrographs of the copolymer nanocomposites reveal a serrated structure reflecting higher mechanical strength, good dispersion, and good interfacial bonding of HA in the polymer matrix. In vitro degradation of the copolymer crosslinked with MMA is relatively more than that of NVP and the degradation decreases with an increase in the amount of the HA filler. The mechanically favorable and degradable MMA based nanocomposites also have favorable bioactivity, blood compatibility, cytocompatibility and cell adhesion. The present nanocomposite is a more promising material for orthopedic applications. (C) 2014 Elsevier B.V. All rights reserved.
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    Calcium Phosphates as Drug Delivery Systems
    (JOURNAL OF BIOMATERIALS AND TISSUE ENGINEERING, 2012) Victor, SP; Sharma, CP
    Calcium phosphate based ceramics present a unique class of materials for orthopaedic and dental applications owing to their wide range of properties that they posses. The strategy of delivering drugs, proteins and growth factors using calcium phosphate carriers represents the most promising approach to improve their bioavailability, reduce the frequency of administration, and to expand the effective routes of administration for effective treatment of bone diseases. The different phases of calcium phosphates exhibit variable solubility, permeability, roughness and porosity, and are decisive factors of drug loading and adsorption. Further the amazing characteristics of nanophase ceramics suggest that they can be excellent for drug transportation and controlled prolonged release. This chapter focuses on the various types of calcium phosphates, their properties and the different systems that have been used for drug and antibiotic delivery. These different forms of micro and nano calcium orthophosphates have great potential as effective carriers of antibiotics, drugs and growth factors to revolutionize the field of hard tissue engineering.
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    Covalently cross-linked hydroxyapatite-citric acid-based biomimetic polymeric composites for bone applications
    (JOURNAL OF BIOACTIVE AND COMPATIBLE POLYMERS, 2015) Victor, SP; Vineeth, VM; Komeri, R; Selvam, S; Muthu, J
    Composite materials based on bioceramics and polymers offer excellent opportunities in the quest for developing optimal bone grafts for bone tissue engineering. Herein, we have functionalized nano hydroxyapatite with citric acid and subsequently cross-linked with poly(propylene fumarate) and poly(ethylene glycol) to afford a composite with better interfacial bonding properties. This study involved two biomimetic composites, 3CP-VP and 5CP-VP, prepared by varying the concentration of hydroxyapatite. Uniform homogenous distribution of hydroxyapatite was identified through Raman spectral imaging in both the composite matrices. The compressive moduli of the biomimetic composites after 4-week immersion in phosphate-buffered saline ranged between 100 and 300MPa, which falls well within the accepted values reported for human trabecular bone. Moreover, biodegradation studies revealed only an average weight loss of 10%-17% during the 7-week time period. Furthermore, apatite mineralization was evaluated using scanning electron microscopy and energy dispersive X-ray analysis, and contact angle measurements revealed hydrophobic surfaces with preferential adsorption to albumin. More importantly, blood compatibility studies demonstrated no significant hemolysis and no visible red blood cell aggregation, while cytotoxicity evaluation via direct contact, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, and live-dead assays on human osteoblast sarcoma cell line exhibited good biocompatibility with negligible cytotoxicity. In addition, in vitro drug release studies with gentamycin-loaded composites demonstrated a controlled and sustained release profile with about 35% of drug released over a period of 2weeks. These findings show that these composites could be developed into stand-alone bone substitutes for bone tissue engineering coupled with drug delivery applications.
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    Cucurbitural/Hydroxyapatite based nanoparticles for potential use in theranostic applications
    (CrystEngComm, 2014-05) Victor, SP; Paul, W; Jayabalan, M; Sharma, CP
    We present the engineering of cucurbituril/hydroxyapatite based theranostic nanoparticles with a high aspect ratio and a needle shaped morphology. These particles with varying sizes, surface charges and tunable degradation profiles manifested the advantages of the presence of cucurbituril with respect to drug loading, encapsulation efficacy and release kinetics. In vitro release profiles with two model drugs, Doxorubicin hydrochloride (Dox, hydrophilic) and Nile Red dye (NR, hydrophobic), were evaluated. It was ascertained that hydrophilic Dox was released at a faster rate compared to hydrophobic NR over similar time periods. The concomitant presence of samarium (Sm3+) and CB[7] confers theranostic potential to the synthesized nanoparticles. Cellular toxicity effects systematically assessed using MTT and live/dead assay protocols indicate inappreciable toxicity. The nanoparticles further reveal excellent blood compatibility and cellular internalization properties as visualized by fluorescence microscopy. Particles excited at 300 nm revealed Dox emission in the green channel (470 nm) as well as Sm3+ emission in the red channel (590 nm). These studies unravel the potential of these nanoparticles for effective theranostic applications.
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    Cucurbituril/hydroxyapatite based nanoparticles for potential use in theranostic applications
    (CRYSTENGCOMM, 2014) Victor, SP; Paul, W; Jayabalan, M; Sharma, CP
    We present the engineering of cucurbituril/hydroxyapatite based theranostic nanoparticles with a high aspect ratio and a needle shaped morphology. These particles with varying sizes, surface charges and tunable degradation profiles manifested the advantages of the presence of cucurbituril with respect to drug loading, encapsulation efficacy and release kinetics. In vitro release profiles with two model drugs, Doxorubicin hydrochloride (Dox, hydrophilic) and Nile Red dye (NR, hydrophobic), were evaluated. It was ascertained that hydrophilic Dox was released at a faster rate compared to hydrophobic NR over similar time periods. The concomitant presence of samarium (Sm3+) and CB[7] confers theranostic potential to the synthesized nanoparticles. Cellular toxicity effects systematically assessed using MTT and live/dead assay protocols indicate inappreciable toxicity. The nanoparticles further reveal excellent blood compatibility and cellular internalization properties as visualized by fluorescence microscopy. Particles excited at 300 nm revealed Dox emission in the green channel (470 nm) as well as Sm3+ emission in the red channel (590 nm). These studies unravel the potential of these nanoparticles for effective theranostic applications.
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    Injectable in situ forming xylitol-PEG-based hydrogels for cell encapsulation and delivery
    (COLLOIDS AND SURFACES B-BIOINTERFACES, 2015) Selvam, S; Pithapuram, MV; Victor, SP; Muthu, J
    Injectable in situ crosslinking hydrogels offer unique advantages over conventional prefabricated hydrogel methodologies. Herein, we synthesize poly(xylitol-co-maleate-co-PEG) (pXMP) macromers and evaluate their performance as injectable cell carriers for tissue engineering applications. The designed pXMP elastomers were non-toxic and water-soluble with viscosity values permissible for subcutaneous injectable systems. pXMP-based hydrogels prepared via free radical polymerization with acrylic acid as crosslinker possessed high crosslink density and exhibited a broad range of compressive moduli that could match the natural mechanical environment of various native tissues. The hydrogels displayed controlled degradability and exhibited gradual increase in matrix porosity upon degradation. The hydrophobic hydrogel surfaces preferentially adsorbed albumin and promoted cell adhesion and growth in vitro. Actin staining on cells cultured on thin hydrogel films revealed subconfluent cell monolayers composed of strong, adherent cells. Furthermore, fabricated 3D pXMP cell-hydrogel constructs promoted cell survival and proliferation in vitro. Cumulatively, our results demonstrate that injectable xylitol-PEG-based hydrogels possess excellent physical characteristics and exhibit exceptional cytocompatibility in vitro. Consequently, they show great promise as injectable hydrogel systems for in situ tissue repair and regeneration. (C) 2014 Elsevier B.V. All rights reserved.
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    Magnetic and degradable polymer/bioactive glass composite nanoparticles for biomedical applications
    (COLLOIDS AND SURFACES B-BIOINTERFACES, 2013) Jayalekshmi, AC; Victor, SP; Sharma, CP
    The present study focuses on the development of a biocompatible and biodegradable iron oxide incorporated chitosan-gelatin bioglass composite nanoparticles [Fe-BG]. The developed composite nanoparticle was analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermo gravimetric analysis (TG) and differential scanning calorimetry analysis (DSC). The size of the negatively charged composite nanoparticle was in the range of 43-51 nm. The in vitro analysis of the composite nanoparticles was carried out by cell aggregation, protein adsorption and haemolytic activity. The magnetic hysteresis value of the composite nanoparticle showed that it is a soft magnetic material. The presence of iron oxide in the chitosan-gelatin bioglass [BG] matrix enhances biodegradability as indicated in the TG studies. Iron-oxide in equal amount to bioglass in the polymer matrix has been obtained as the optimized system. The developed composite nanoparticle is a soft magnetic material and is suitable for the magnetic hyperthermia treatment and drug delivery. More detailed in vivo studies are needed to confirm the biodegradation profile and biological activity of the material. (C) 2012 Elsevier B.V. All rights reserved.
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    Neodymium doped hydroxyapatite theranostic nanoplatforms for colon specific drug delivery applications
    (COLLOIDS AND SURFACES B-BIOINTERFACES, 2016) Victor, SP; Paul, W; Vineeth, VM; Komeri, R; Jayabalan, M; Sharma, CP
    Theranostic nanoplatforms integrate therapeutic payloads with diagnostic agents, and help monitor therapeutic response. In this regard, stimuli responsive nanoplatforms further favour combinatorial therapeutic approach that can considerably improve efficacy and specificity of treatment. Herein, we present the engineering of a smart theranostic nanoplatform based on neodymium doped hydroxyapatite (HAN). The presence of neodymium endows the HAN nanoplatforms with near-infrared fluorescence capability. These HAN nanoparticles were then subsequently modified with alginic acid (HANA) to confer pH responsiveness to the synthesized nanoplatforms delivering them to the colon after oral administration. These nanoplatforms possessing optimum size, needle shaped morphology and negative zeta potential, are conducive to cellular internalization. On excitation at 410 nm they exhibit near infrared emission at 670 nm unraveling their theranostic capabilities. Cytotoxic effects systematically assessed using MIT and live dead assays reveal excellent viability. Raman microscopic imaging technique used to visualize uptake in HeLa cells demonstrate increased uptake from 4 to 16 h, with growing cluster size and localization in the cytoplasm. Moreover the concomitant presence of alginic acid manifested advantages of augmented loading and pH dependent release profiles of the model drug, 4 acetyl salicylic acid (4ASA). We could thus establish a theranostic system for early tumour detection, targeted tumour therapy and monitoring of colon cancer that can be administered via the oral route. (C) 2016 Elsevier B.V. All rights reserved.
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    Photoluminescent PEG based comacromers as excitation dependent fluorophores for biomedical applications
    (COLLOIDS AND SURFACES B-BIOINTERFACES, 2015) Vijayan, VM; Komeri, R; Victor, SP; Muthu, J
    We report a novel multi-modal biodegradable photoluminescent comacromer [poly(propylene fumarate)-PEG-glycine] (PLM) having excitation-dependent fluorescence (EDF) for biomedical applications. The photoluminescence of the synthesized PLM in aqueous and solid state condition, fluorescence life time and photo stability were evaluated. Hydrogels and nanogels were prepared from the PLM by cross linking with acrylic acid. Nanogels exhibited spherical morphology with a particle size of 100 nm as evaluated by transmission electron microscopy (TEM). In vitro cytotoxic and hemolytic studies revealed cytocompatibility. Furthermore, cellular imaging of nanogels on L929 fibroblast and Hela cell lines revealed EDF characteristics. We hypothesize that the EDF characteristics of the synthesized PLM may be attributed to the presence of n-pi* interactions of the hydroxyl oxygen atoms of PEG with carbonyl groups of the ester linkages. Taken together, our results indicate that the synthesized PEG-based comacromer can serve as biocompatible fluorophores for various biomedical applications. More importantly, the facile way of synthesizing fluorescent polymers based on PEG with EDF characteristics demonstrated in this work can pave the way for developing more novel biocompatible fluorophores with wide range of biomedical applications. (C) 2015 Elsevier B.V. All rights reserved.
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    Photoluminescent PEG based comacromers as excitation dependent fluorophores for biomedical applications.
    (Colloids and Surfaces B: Biointerfaces, 2015-09) Vijayan, VM; Komeri, R; Victor, SP; Muthu, J
    We report a novel multi-modal biodegradable photoluminescent comacromer [poly(propylene fumarate)-PEG-glycine] (PLM) having excitation-dependent fluorescence (EDF) for biomedical applications. The photoluminescence of the synthesized PLM in aqueous and solid state condition, fluorescence life time and photo stability were evaluated. Hydrogels and nanogels were prepared from the PLM by cross linking with acrylic acid. Nanogels exhibited spherical morphology with a particle size of 100 nm as evaluated by transmission electron microscopy (TEM). In vitro cytotoxic and hemolytic studies revealed cytocompatibility. Furthermore, cellular imaging of nanogels on L929 fibroblast and Hela cell lines revealed EDF characteristics. We hypothesize that the EDF characteristics of the synthesized PLM may be attributed to the presence of n–π* interactions of the hydroxyl oxygen atoms of PEG with carbonyl groups of the ester linkages. Taken together, our results indicate that the synthesized PEG-based comacromer can serve as biocompatible fluorophores for various biomedical applications. More importantly, the facile way of synthesizing fluorescent polymers based on PEG with EDF characteristics demonstrated in this work can pave the way for developing more novel biocompatible fluorophores with wide range of biomedical applications.
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    Poly methacrylic acid modified CDHA nanocomposites as potential pH responsive drug delivery vehicles
    (Colloids Surf B Biointerfaces, 2013-04) Victor, SP; Sharma, CP
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    Poly Methacrylic acid modified CDHA nanocomposites as potential pH responsive drug delivery vehicles
    (Colloids and Surfaces B: Biointerfaces, 2013-03) Victor, SP; Sharma, CP
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    Polymer Ceramic Composite Materials for Orthopedic Applications . Relevance and need for mechanical match and bone regeneration
    (J. Mechatron, 2014-01) Victor, SP; Jayabalan, M
    Polymer/Ceramic composites are now being considered as third-generation orthopedic biomaterials due to their ability to closely match properties of natural bone when compared with first generation and second generation bone substitute materials. The combination of polymers and ceramic phases leads to composite materials with improved mechanical properties due to the inherent higher stiffness and strength of the inorganic material. Among all existing biomaterials calcium phosphate ceramics have been extensively used for bone replacement and augmentation due to their similarity to the mineral component of bone. They also have the additional benefits of biocompatibility, bioactivity and nontoxicity. This review focuses on selected polymer ceramic composites, their physical and biological properties. It also includes their current biomedical applications like bone fillers, coatings, cements, scaffolds and drug carriers. These composites are promising as bone substitute materials. They have great potential starting from bone augmentation, to controlled delivery devices to revolutionize the field of hard tissue engineering.
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    Protein-Bioceramic Interactions at the Interface
    (PROTEINS AT INTERFACES III: STATE OF THE ART, 2012) Victor, SP; Sharma, CP
    Calcium phosphate based ceramics are indispensable in biomaterial and hard tissue application due to their chemical similarity to the mineral component of mammalian bones and teeth. Their interfacial behaviour with proteins determines cellular responses that play a pivotal role in determining the degree of biocompatibility. The control of the cell response to artificial hard tissue substitutes is of crucial importance in terms of biocompatibility. The selective nature of protein adsorption and the functionality of the adsorbed bio molecule are influenced by the physicochemical characteristic of the calcium phosphate material. This chapter focuses on the various factors like ionic composition, surface activity, monolayer adsorption, pH, solution strength and temperature that determine the kinetics of protein adsorption. It also includes the selective adsorption of proteins in competition to nonadhesive proteins to different calcium phosphate surfaces. These interfacial phenomena with the cell adhesion on protein adsorbed calcium phosphate surfaces indicate biocompatibility due to surface properties and have great potential to revolutionize the field of hard tissue engineering.
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    Stimuli sensitive polymethacrylic acid microparticles (PMAA) - Oral insulin delivery
    (JOURNAL OF BIOMATERIALS APPLICATIONS, 2002)
    This study investigated polymethacrylic acid (PMAA) microparticles for controlled release of Insulin in oral administration. The microparticles were characterised by scanning electron microscopy (SEM) for morphological studies. The swelling behaviour and drug release profile in various pH media were studied. The % swelling of gels was found to be inversely related to the amount of crosslinker added. Inclusion complex of betaCD and Insulin was studied using polyacrylamide gel electrophoresis (PAGE). Optimum complexation was obtained in the ratio 100 mg betaCD: 200IU Insulin. The release pattern of Insulin from Insulin-betaCD complex encapsulated PMAA microparticles showed release of Insulin for more than seven hours.
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    Stimulus responsive nanogel with innate near IR fluorescent capability for drug delivery and bioimaging
    (Colloids and Surfaces B: Biointerfaces, 2016-06) Vijayan, VM; Shenoy, SJ; Victor, SP; Muthu, J
    A brighter, non toxic and biocompatible optical imaging agent is one of the major quests of biomedical research. Here in, we report a photoluminescent comacromer [PEG-poly(propylene fumarate)-citric acid-glycine] and novel stimulus (pH) responsive nanogel endowed with excitation wavelength dependent fluorescence (EDF) for combined drug delivery and bioimaging applications. The comacromer when excited at different wavelengths in visible region from 400 nm to 640 nm exhibits fluorescent emissions from 510 nm to 718 nm in aqueous condition. It has high Stokes shift (120 nm), fluorescent lifetime (7 nanoseconds) and quantum yield (50%). The nanogel, C-PLM-NG, prepared with this photoluminescent comacromer and N,N-dimethyl amino ethylmethacrylate (DMEMA) has spherical morphology with particle size around 100 nm and 180 nm at pH 7.4 (physiological) and 5.5 (intracellular acidic condition of cancer cells) respectively. The studies on fluorescence characteristics of C-PLM NG in aqueous condition reveal large red-shift with emissions from 523 nm to 700 nm for excitations from 460 nm to 600 nm ascertaining the EDF characteristics. Imaging the near IR emission with excitation at 535 nm was accomplished using cut-off filters. The nanogel undergoes pH responsive swelling and releases around 50% doxorubicin (DOX) at pH 5.5 in comparison with 15% observed at pH 7.4. The studies on in vitro cytotoxicity with MTT assay and hemolysis revealed that the present nanogel is non-toxic. The DOX-loaded C-PLM-NG encapsulated in Hela cells induces lysis of cancer cells. The inherent EDF characteristics associated with C-PLM NG enable cellular imaging of Hela cells. The studies on biodistribution and clearance mechanism of C-PLM-NG from the body of mice reveal bioimaging capability and safety of the present nanogel. This is the first report on a polymeric nanogel with innate near IR emissions for bioimaging applications.
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    Supramolecular hydroxyapatite complexes as theranostic near-infrared luminescent drug carriers
    (CrystEngComm, 2014-07) Victor, SP; Paul, W; Jayabalan, M; Sharma, CP
    The facile synthesis of luminescent, multifunctional, needle-like hydroxyapatite (HA) nanoparticle complexes containing cyclodextrin has been reported. The in vitro loading and release studies using doxorubicin hydrochloride (DOX) demonstrate that the nanoparticle complexes show high drug adsorption capacity and sustained drug release profiles. Moreover, they exhibit strong photoluminescence even after loading of DOX molecules and permit the monitoring of the photoluminescence intensity. The nanocomplexes further reveal excellent blood compatibility, inappreciable toxicity and cellular internalization properties. Upon excitation at 420 nm, these complexes exhibit strong near-infrared emission at 680 nm. The photoluminescence intensity of the nanoparticles can be adjusted by varying the concentration of neodymium. Thus, the nanoparticle complexes obtained in the present study are promising for applications in the biomedical field as multifunctional drug delivery systems for simultaneous targeted drug delivery and near-infrared fluorescence imaging guidance.
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    Use of quartz crystal nanobalance to study the binding and stabilization of albumin and doxycycline on a thin layer of hydroxyapatite
    (APPLIED SURFACE SCIENCE, 2011) Victor, SP; Sharma, CP; Sreenivasan, K
    This study reports the use of quartz crystal nanobalance (QCN) to study the adsorption of two model molecules namely albumin and doxycycline by hydroxyapatite (HA). The work focuses on the deposition of a stable coating of HA on the quartz crystal, modification of the coating using doxycycline and its subsequent effects on albumin adsorption. The uniformity and thickness of the HA coating has been studied using atomic force microscopy (AFM). The functional groups to ascertain the presence of the selected moieties have been characterized by Raman spectroscopy. The results indicate that the mass of albumin deposited on the surface of the HA coated quartz crystal functionalized with doxycycline shows a substantial increase when compared to the standard HA coated quartz crystal. The adsorbed albumin has also been found to be retained for an enhanced period of time. This surface immobilization of doxycycline and subsequent albumin adsorption seem to be a promising approach to confer biomaterials with antithrombogenic and antibacterial surfaces. (C) 2011 Elsevier B. V. All rights reserved.