Browsing by Author "Komath, M"

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    Biomimetic deposition of hydroxyapatite on titanium with help of sol-gel grown calcium pyrophosphate prelayer
    (MATERIALS RESEARCH INNOVATIONS, 2011) Sureshbabu, S; Komath, M; Shibli, SMA; Varma, HK
    The biomimetic method is a cost effective, low temperature route for coating hydroxyapatite on titanium bone implants so as to provide an osteointegrating interface. However, biomimetic coatings have the limitations of poor adhesion and lower growth rates. This work investigates the role of a prelayer of calcium pyrophosphate made through sol-gel technique in growing adherent and thick layer of biomimetic hydroxyapatite over titanium surface. Cleaned titanium substrates were dip coated in a calcium-phosphate-citrate sol and calcined at 650 degrees C to form an adherent calcium phosphate layer. These were then subjected to biomimetic processing in 1.5 simulated body fluid for 7-14 days. The prelayer and the biomimetic layer were analysed for micromorphology (using SEM) and chemical phase (using X-ray diffraction, Fourier transform infrared spectroscopy and energy dispersive X-ray spectroscopy). Thickness measurements were performed on an optical profilometer and the adhesion was assessed through a microcombi scratch tester. The prelayer showed petal-like morphology, whereas globular particles were seen in the biomimetic growth. The prelayer had a thickness of 3.6 mu m and was found to contain calcium pyrophosphate, with calcium titanate at the interface. The phase in the biomimetic layer was identified to be hydroxyapatite, with a growth rate of 5.3 mu m/day. The scratch test gave the delamination load for this layer to be 6.23 N. Results show that it is possible to obtain adherent hydroxyapatite layer on the titanium surface at a faster rate by combining the sol-gel coating and the biomimetic growth technique.
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    Contact Guidance Mediated by Hybrid Thread Topography Enhances Osseointegration of As-machined Ti6Al4V Dental Implant.
    (Regenerative Engineering and Translational Medicine, 2023-03) Mishra, D; Neethu, RS; Shetty, V; Shenoy, SJ; Komath, M; Varma, HK; Sabareeswaran, A; Basu, B
    Purpose The main objective of this study is to investigate the key role of as-machined implant design features on the osseointegration. The bone regeneration ability of the newly developed Ti6Al4V hybrid threaded tapered implant without any surface modification has been validated and benchmarked against Straumann® implant (control) in the rabbit model for 12 weeks. Material and Methods The test and control implants were implanted in the femur medial condyle of twelve adult New Zealand white rabbits on the contralateral limbs; each femoral medial condyle received a test or control implant randomly. The bone formation and osseointegration around the implants were assessed qualitatively and quantitatively using histology, micro-computed tomography (Micro-CT), molecular gene studies, and histomorphometric analysis after 12 weeks of implantation. Results The overall assessment suggests homogenous and continuous neobone formation and osseointegration around the hybrid threads of the test implants. Superior bone-to-implant contact percentage (BIC) was observed in the case of hybrid threaded test implants with an average value of 80.8%, compared to 67.1% for the control implant. Upregulated expression of osteogenic (COL1A1, RUNX2, SPARC, and SPP1) and angiogenic (VEGF) genes in the case of test implant indicates better coupled osseointegrationa and angiogenesis. Conclusion It can be concluded that the extent of neobone formation and expression of the osteogenic/angiogenic genes is positively correlated with optimal design features of the implant, which leads to the contact guidance of the osteoblasts on the implant surface. The study also advocates that the novel tapered multithreaded implant design concept alone, without any surface modification, can facilitate osseointegration in a manner better than clinically used surface-modified implants. Lay Summary Dental implants are artificial tooth roots and are used to treat complete or partial toothlessness. The new implant design concept reported here is expected to support both soft tissue and hard tissue attachment and to improve primary stability. This study unraveled the effect of the novel external hybrid thread design on the implant integration with the surrounding bone. This aspect was validated in the rabbit model and benchmarked against the commercially available Straumann® implant. This study has unambiguously demonstrated the ability of as-machined Ti implants to facilitate better new bone and new blood vessels formation than the commercial implant.
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    Development of a fully injectable calcium phosphate cement for orthopedic and dental applications
    (BULLETIN OF MATERIALS SCIENCE, 2003) Komath, M; Varma, HK
    A study on the development of a fully injectable calcium phosphate cement for orthopedic and dental applications is presented. The paper describes its characteristic properties including results of biocompatibility studies. A conventional two-component calcium phosphate cement formulation (having a powder part containing dry mixture of acidic and basic calcium phosphate particles and a liquid part containing phosphate solution) is modified with a biocompatible gelling agent, to induce flow properties and cohesion. The quantity of the gelling agent is optimized to get a viscous paste, which is smoothly injectable through an 18-gauge needle, with clinically relevant setting parameters. The new formulation has a setting time of 20 min and a compressive strength of 11 MPa. The X-ray diffraction, Fourier transform infrared spectrometry, and energy dispersive electron microprobe analyses showed the phase to be hydroxyapatite, the basic bone mineral. Scanning electron microscopy revealed a porous structure with particle sizes of a few micrometers. The cement did not show any appreciable dimensional or thermal change during setting. The injectability is estimated by extruding through needle and the cohesive property is assessed by water contact method. The cement passed the in vitro biocompatibility screening (cytotoxicity and haemolysis) tests.
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    Development of an injectable bioactive bone filler cement with hydrogen orthophosphate incorporated calcium sulfate
    (J Mater Sci Mater Med., 2015-03) Sony, S; Suresh Babu, S; Nishad, KV; Varma, H; Komath, M
    Calcium sulfate cement (CSC) has emerged as a potential bone filler material mainly because of the possibility of incorporating therapeutic agents. Delivery of the cement through a needle or cannula will make it more useful in clinical applications. However, it was not possible to make CSC injectable because of the inherent lack of viscosity. The present work demonstrates the design development of a viscous and fully-injectable CSC by incorporating hydrogen orthophosphate ions, which does not hamper the biocompatibility of the material. The effect of addition of hydrogen orthophosphate on the rheological properties of the CSC paste was studied using a custom made capillary rheometer. The physicochemical changes associated with cement setting process were examined using X-ray diffraction and Fourier transform infrared spectroscopy and the thermal changes were measured through isothermal differential scanning calorimetry. Micromorphological features of different compositions were observed in environmental scanning electron microscopy and the presence of phosphate ions was identified with energy dispersive X-ray spectroscopic analysis and inductively coupled plasma–optical emission spectroscopy. The results indicated that HPO4 2− ions have profound effects on the rheological properties and setting of the CSC paste. Significant finding is that the HPO4 2− ions are getting substituted in the calcium sulfate dihydrate crystals during setting. The variations of setting time and compressive strength of the cement with the additive concentration were investigated. An optimum concentration of 2.5 % w/w gave a fully-injectable cement with clinically relevant setting time (below 20 min) and compressive strength (12 MPa). It was possible to inject the optimised cement paste from a syringe through an 18-gauge needle with thumb pressure. This cement will be useful both as bone filler and as a local drug delivery medium and it allows minimally invasive bone defect management.
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    Formation of hydroxyapatite coating on titanium at 200A degrees C through pulsed laser deposition followed by hydrothermal treatment
    (BULLETIN OF MATERIALS SCIENCE, 2011) Komath, M; Rajesh, P; Muraleedharan, CV; Varma, HK; Reshmi, R; Jayaraj, MK
    Pulsed laser deposition (PLD) has emerged as an acceptable technique to coat hydroxyapatite on titanium-based permanent implants for the use in orthopedics and dentistry. It requires substrate temperature higher than 400A degrees C to form coatings of good adhesion and crystallinity. As this range of temperatures is likely to affect the bulk mechanical properties of the implant, lowering the substrate temperature during the coating process is crucial for the long-term performance of the implant. In the present study, hydroxyapatite target was ablated using a pulsed Nd:YAG laser (355 nm) onto commercially pure titanium substrates kept at 200A degrees C. The coating thus obtained has been subjected to hydrothermal treatment at 200A degrees C in an alkaline medium. The coatings were analysed using microscratch test, optical profilometry, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and infrared spectroscopy (FTIR). XRD, EDS and FTIR showed that the as-deposited coating contained amorphous calcium phosphate and the hydrothermal treatment converted it into crystalline hydroxyapatite. The micro-morphology was granular, with an average size of 1 micron. In the micro-scratch test, a remarkable increase in adhesion with the substrate was seen as a result of the treatment. The plasma plume during the deposition has been analysed using optical emission spectroscopy, which revealed atomic and ionic species of calcium, phosphorous and oxygen. The outcomes demonstrate the possibility of obtaining adherent and crystalline hydroxyapatite on titanium substrate at 200A degrees C through pulsed laser deposition and subsequent hydrothermal treatment.
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    In Situ Formation of Hydroxyapatite - Alpha Tricalcium Phosphate Biphasic Ceramics with Higher Strength and Bioactivity
    (JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 2012) Sureshbabu, S; Komath, M; Varma, HK
    Synthetic bone grafts based on hydroxyapatitealpha tricalcium phosphate (HA/a-TCP) biphasic system are preferred for their higher resorbability and bioactivity. In this work, a viable method is suggested to produce HA/a-TCP systems with enhanced bioactivity and mechanical strength, through the in situ conversion of calcium-deficient apatite precursor. A homogeneous precipitation technique was used to produce the precursor powder. It was heat-treated to study the phase conversion using XRD and FTIR. The precursor got converted HA/beta-TCP system above 762 degrees C, which further transformed to HA/a-TCP system after 1165 degrees C. The sintering temperature was optimized at 1175 degrees C. It is the net Ca/P ratio of the precursor which decides the ratio of the phases in the final ceramic. The precursor with Ca/P = 1.585 gave a biphasic ceramic containing 47% a-TCP. The flexural strength of this sample was more than 2.5 times higher compared to the biphasic ceramic made by sintering HA/a-TCP powder mix. The internal microstructure of the ceramic revealed the formation of a-TCP in sheet-like morphology. Preferential dissolution of the a-TCP from the sample surface in aqueous and acidic environment was confirmed quantitatively. Biomimetic growth technique in simulated body fluid has been used to assess the bioactivity in vitro.
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    Mesenchymal stem cell culture in aligned porous hydroxyapatite scaffolds using a multiwell plate bioreactor for bone tissue engineering
    (MedComm – Future Medicine, 2022-09) Gayathry, G; Athira, RK; Anju, MS; Anil Kumar, PR; Harikrishna Varma, PR; Kasoju, N; Komath, M
    Regeneration of bone lost by trauma, diseases and aging, and restoration of its load-bearing function are major clinical challenges. Hydroxyapatite (HA) is a clinically proven scaffold material for bone grafting, but the random-pore structure limits the homing of the cells inside the graft and the bone regeneration progresses with the resorption of the graft material. This work is based on the hypothesis that aligned through pores in the graft will lead to a faster healing by homing the local cells inside and provide a better environment for new bone formation through the graft structure. The investigation was done using aligned porous HA scaffolds seeded with human Wharton's jelly-derived mesenchymal stem cells (hWJ-MSCs) and cultured in a multiwell format bioreactor setup. The cell adhesion was studied by microscopy, cell proliferation was evaluated by Alamar blue assay and osteogenic differentiation was confirmed by biochemical and molecular assays. The results indicate that the hWJ-MSCs infiltrated through the aligned porous network of the scaffold, proliferated well when cultured in the expansion medium, and differentiated into osteogenic lineage when cultured in the differentiation medium.
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    Nucleation kinetics of the formation of low dimensional calcium sulfate dihydrate crystals in isopropyl alcohol medium
    (CRYSTAL RESEARCH AND TECHNOLOGY, 2012) Sandhya, S; Sureshbabu, S; Varma, HK; Komath, M
    Calcium sulfate dihydrate, constituted as uniform crystals of low dimensions, is a potential biomaterial for clinical applications like bone graft substitution and drug delivery. In this work, isopropyl alcohol has been used as a solvent to obtain low dimensional calcium sulfate dihydrate crystals from calcium nitrate - sulfuric acid system. Reactants in 0.5 molar concentration at ambient conditions generated uniform rod-shaped crystals of length 35 mu m. Analysis using X-ray Diffractometry and Fourier Transform Infrared Spectrometry showed the material to be well crystallized, phase-pure calcium sulfate dihydrate. The nucleation kinetics has been studied by observing the induction time of phase formation in solutions of millimolar concentrations through turbidimetry at 300 K. The data have been analysed using classical nucleation theory to deduce parameters like interfacial tension (or surface free energy), nucleation rate and critical radius. The surface free energy obtained (5.6 mJ/m2) is comparatively lower than that reported for aqueous precipitation, which could be attributed to the presence of isopropyl alcohol. On escalating the supersaturation ratio, the nucleation rate drastically increased and the critical radius decreased exponentially. Particles formed at supersaturation 1.39 showed a monomodal distribution centered at 8.2 nm in Dynamic Light Scattering analysis. Comparable particle sizes were obtained in Transmission Electron Microscopy.
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    On the development of an apatitic calcium phosphate bone cement
    (BULLETIN OF MATERIALS SCIENCE, 2000) Komath, M; Varma, HK; Sivakumar, R
    Development of an apatitic calcium phosphate bone cement is reported. 100 mu Particles of tetracalcium phosphate (TTCP) and dicalcium phosphate dihydrate (DCPD) were mixed in equimolar ratio to form the cement powder. The wetting medium used was distilled water with Na2HPO4 as accelerator to manipulate the setting time. The cement powder, on wetting with the medium, formed a workable putty. The setting times of the putty were measured using a Vicat type apparatus and the compressive strength was determined with a Universal Testing Machine. The nature of the precipitated cement was analyzed through X-ray diffraction (XRD), fourier transform infrared spectrometry (FTIR) and energy dispersive electron microprobe (EDAX). The results shelved the phase to be apatitic with a calcium-to-phosphorous ratio close to that of hydroxyapatite. The microstructure analysis using scanning electron microscopy (SEM) showed hydroxyapatite nanocrystallite growth over particulate matrix surface. The structure has an apparent porosity of similar to 52%. There were no appreciable dimensional or thermal changes during setting. The cement passed the in vitro toxicological screening (cytotoxicity and haemolysis) tests. Optimization of the cement was done by manipulating the accelerator concentration so that the setting time, hardening time and the compressive strength had clinically relevant values.
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    On those heavenly pathogens ...
    (CURRENT SCIENCE, 2000) Komath, M
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    Orthopaedic segment in India – from pandemic dormancy to a better future
    (Current Science, 2022-02) Prajapati, AK; Komath, M
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    Photoluminescence and thermolumineseence properties of tricalcium phosphate phosphors doped with dysprosium and europium
    (BULLETIN OF MATERIALS SCIENCE, 2007) Madhukumar, K; Varma, HK; Komath, M; Elias, TS; Padmanabhan, V; Nair, CMK
    The suitability of calcium phosphate crystals for thermoluminescence dosimetry (TLD) applications is investigated, owing to their equivalence to bone mineral. The alpha and beta phases of tricalcium phosphate (TCP) were synthesized through wet precipitation and high temperature solid state routes and doped with Dy and Eu. The photoluminescence and thermolumineseence studies of the phosphors have been carried out. The TL properties were found to be highly dependent on the method of preparation of the material. Eu doping gave good PL emission, whereas Dy doping was more efficient in TL emission. beta-TCP was found to be less TL sensitive than alpha-TCP, yet it was identified as a better phosphor material owing to its better fading characteristics. The dependence of TL of beta-TCP: Dy on the energy and dose of radiation, and on the doping concentration were studied. The TL intensity was observed to fade exponentially during a storage period of 20 days, but it stabilized at 70% of the initial value after 30 days. The optimum doping concentration was found to be 0.5 mol %.
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    Plasma surface modification of polystyrene and polyethylene
    (APPLIED SURFACE SCIENCE, 2004) Guruvenket, S; Rao, GM; Komath, M; Raichur, AM
    Polystyrene (PS) and polyethylene (PE) samples were treated with argon and oxygen plasmas. Microwave electron cyclotron resonance (ECR) was used to generate the argon and oxygen plasmas and these plasmas were used to modify the surface of the polymers. The samples were processed at different microwave powers and treatment time and the surface modification of the polymer was evaluated by measuring the water contact angle of the samples before and after the modification. Decrease in the contact angle was observed with the increase in the microwave power for both polystyrene and polyethylene. Plasma parameters were assessed using Langmuir probe measurements. Fourier transform infrared spectroscopy showed the evidence for the induction of oxygen-based functional groups in both polyethylene and polystyrene when treated with the oxygen plasma. Argon treatment of the polymers showed improvement in the wettability which is attributed to the process called as CASING, on the other hand the oxygen plasma treatment of the polymers showed surface functionalization. Correlation between the plasma parameters and the surface modification of the polymer is also discussed. (C) 2004 Elsevier B.V. All rights reserved.
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    Prosthetics and orthotics for persons with movement disabilities in India in the postpandemic milieu
    (Prosthet Orthot Int, 2023-11) Prajapati, AK; Komath, M; Subhash, NN
    The SARS-CoV-2 disease had a severe impact on global socioeconomic growth, and its harmful effects continue with virus mutation. Over the past 3 years, the pandemic has caused isolation, mental trauma, stress, financial losses, and various health complications in individuals. Recent reports have stressed the sufferings of the physically abled population. However, we should not neglect the challenges faced by the disabled population, which were more severe in many ways due to their dependency on others at various levels. The strategies implemented to contain the virus have further aggravated their sufferings and made it even worse because health care priorities were skewed toward public-centered care. As a result, it is difficult to determine the extent of care the disabled population received during the pandemic. Moreover, a single-centered study reports that amputations in India increased by 54.1% compared with those during the prepandemic era. This indicates the need for special attention to the physically disabled community, especially persons with movement disabilities. These individuals are partially dependent and have the potential to make significant contributions to the gross domestic product if included in the human resources pool. The Indian government had launched various initiatives to improve their living status. But delays in policy implementation, reduction in budget allocation, and the ongoing pandemic have derailed the efforts. For these reasons, this article emphasizes several challenges in movement disability care. In addition, it makes recommendations for improving the quality of life of persons with movement disabilities. These include collaboration, creating start-up businesses, applying state-of-the-art logistics, establishing a technological ecosystem, raising public awareness, accessing high-quality care, and using contemporary medical devices.
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    Safety and efficacy of Chitra-CPC calcium phosphate cement as bone substitute
    (CURRENT SCIENCE, 2006) Fernandez, AC; Mohanty, M; Varma, HK; Komath, M
    Calcium phosphate cements (CPCs) have gained importance in orthopaedics and dentistry as repair materials for bony/dentinal defects. They are aqueous based, mouldable and osteoconductive materials which set into hydroxyapatite, the basic mineral of bone and teeth. A CPC product 'Chitra-CPC' has been developed. This communication compiles the safety and efficacy evaluation of Chitra-CPC. The evaluation plan consisted of acute systemic toxicity test (in mice for systemic response), intracutaneous reactivity test (in rabbits for skin response), pyrogen test (in rabbits for presence of pyrogens) and maximization sensitization test (in guinea pigs for allergic skin response). Soft tissue response was tested by implantation in rabbit paravertebral muscle, with histological evaluation at 1, 4 and 12 weeks post-implantation. The efficacy of the product to heal bone defects was investigated by implanting in rabbit femur with hydroxyapatite ceramic granules as the control. Local effects at macroscopic and microscopic levels were assessed at time periods of 4, 12, 26 and 52 weeks post implantation. The cement did not show any adverse effects in the acute systemic toxicity. Nor did it elicit any erythemic or edematous reactivity in the intracutaneous reactivity test. The maxindzation sensitization study did not show any adverse skin response and the pyrogen test did not evoke undue temperature rise. In the muscle implantaion test, there was no haemorrhage, infection or necrosis. Localized vascularization was present near the implanted region. Chronic inflammation was observed in 1 week, which became mild by 12 weeks with the evidence of repair. Bone implantation studies showed that efficacy of Chitra-CPC and hydroxyapatite granules in bone healing is comparable. Both materials were found to be osteoconductive, but with the difference that Chitra-CPC resorbed progressively allowing simultaneous new bone formation. This proves the osteotransductivity of Chitra-CPC, which is the ideal property for a bone substitute.
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    Synthesis of chemically pure, luminescent Eu3+ doped HAp nanoparticles: a promising fluorescent probe for in vivo imaging applications
    (PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 2013) Hasna, K; Kumar, SS; Komath, M; Varma, MR; Jayaraj, MK; Kumar, KR
    The poor solubility, poor biocompatibility and disposal issues make fluorescent quantum dots such as CdSe, CdS, ZnS, InP, InAs, etc. impractical for imaging tissues or intercellular structures. As calcium phosphate is the main inorganic component of human bone and teeth, hydroxyapatite (Ca-10(PO4)(6)(OH)(2), HAp) is highly biocompatible and bioactive. Since HAp nanoparticles are not luminescent, a novel inorganic biocompatible fluorescent probe was suggested by doping HAp with lanthanides. Here we report the growth of chemically pure fluorescent HAp nanoparticles synthesized by a new methodology, liquid phase pulsed laser ablation using third harmonics (355 nm) of Nd-YAG laser. Europium doped HAp nanoparticles show emission with prominent peaks at 531 nm, 572 nm, 601 nm and 627 nm upon excitation at a wavelength of 325 nm. The red luminescence could also be observed under visible excitation at 459 nm and is suitable for living cell applications.
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    Testing astrology
    (CURRENT SCIENCE, 2009) Komath, M
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    Wettability enhancement of polystyrene with electron cyclotron resonance plasma with argon
    (JOURNAL OF APPLIED POLYMER SCIENCE, 2003) Guruvenket, S; Komath, M; Vijayalakshmi, SP; Raichur, AM; Rao, GM
    Polystyrene cell-culture substrates were treated with argon glow discharge to make their surfaces hydrophilic. The process was novel in that it used a microwave electron cyclotron resonance (ECR) source for polymer surface modification. The substrates were processed at different microwave powers and time periods, and the surface modification was assessed with by measurement of the water contact angle. A decrease in contact angle was observed with increasing microwave power and processing time. Beyond a certain limit of power and duration of exposure, however, surface deterioration occurred. The optimum conditions for making the surfaces hydrophilic without deterioration of the samples were identified. The plasma parameters were assessed by Langmuir probe measurement. Fourier transform infrared spectroscopy with attenuated total reflectance showed evidence for the induction of hydrophilicity on the surface. The surface micromorphology was examined with scanning electron microscopy. The results prove that the ECR glow discharge was an efficient method for enhancing the wettability of the polymer surfaces. (C) 2003 Wiley Periodicals, Inc.