[Show abstract][Hide abstract] ABSTRACT: A greener and eco-friendly method to leather tanning process has been developed in the present investigation, which is based on d-Lysine aldehyde complex. This can be considered as a substitute for chrome-free tanning process. The physico-chemical and morphological characteristics, resistance to collagenolytic activity and organoleptic properties of the d-Lysine glutaraldehyde tanned leather were evaluated in terms of environmental impact assessment. The shrinkage temperature, denaturation temperature and mechanical strength of tanned leather were analysed by using shrinkage, differential scanning calorimetric and thermomechanical analysis techniques. It has been shown that the above properties of the tanned leather are better than that of glutaraldehyde alone or equal to chrome tanned leather. The density of the fibre structure throughout the cross section indicates the even structure and fibre bundles seem to be less dispersed compared to glutaraldehyde alone; were analysed by using scanning electron microscopic and atomic force microscopic techniques. This tanning tanned leather demonstrated a higher resistance to collagenolytic activity than conventional tanned leather. The tanned leather exhibited good fullness, softness, smoothness, colour and general appearance compared to glutaraldehyde alone. The significant reduction in total solids content such as dissolved solids and suspended solids present in the effluent compared to conventional tanning method is evident from environmental impact assessment studies. This tanning process has the cost advantages due to the possible decrease in chemicals consumptions and net saving from the reduced effluent treatment costs. The improved tanning process reduces generation of toxic waste compared to chrome tanning process and can be regarded as eco-friendly, which reducing the environmental impacts and contributes to the development of greener or cleaner process.
No preview · Article · Mar 2013 · Journal of Cleaner Production
[Show abstract][Hide abstract] ABSTRACT: This work discusses the preparation and characterization of novel collagen scaffolds by using unnatural D-amino acids (Coll-D-AAs)-assisted 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)/N-hydroxyl succinimide(NHS)-initiated crosslinking. The mechanical strength, hydrothermal and structural stability, resistance to biodegradation and the biocompatibility of Coll-D-AAs matrices were investigated. The results from Thermo mechanical analysis, Differential scanning calorimetric analysis and Thermo gravimetric analysis of the Coll-D-AAs matrices indicate a significant increase in the tensile strength (TS, 180 ± 3), % elongation (% E, 80 ± 9), elastic modulus (E, 170 ± 4) denaturation temperature (T d, 108 ± 4) and a significant decrease in decomposition rate (T g, 64 ± 6). Scanning electron microscopic and Atomic force microscopic analyses revealed a well-ordered with properly oriented and well-aligned structure of the Coll-D-AAs matrices. FT-IR results suggest that the incorporation of D-AAs favours the molecular stability of collagen matrix. The D-AAs stabilizing the collagen matrices against degradation by collagenase would have been brought about by protecting the active sites in collagen. The Coll-D-AAs matrices have good biocompatibility when compared with native collagen matrix. Molecular docking studies also indicate better understanding of bonding pattern of collagen with D-AAs. These Coll-D-AAs matrices have been produced in high mechanical strength, thermally and biologically stable, and highly biocompatible forms that can be further manipulated into the functional matrix suitable in designing scaffolds for tissue engineering and regenerative medical applications.
No preview · Article · Feb 2013 · Journal of Biomaterials Science Polymer Edition
[Show abstract][Hide abstract] ABSTRACT: Conversion of fish skins into leather has gained interest among tanners due to their attractive and unique grain structure possessing high market value. The stingray fish belongs to cartilag inous family found in both salt and fresh coastal waters as well as some rivers around the world. Instead of scales the dorsal portion of the stingray skins are having denticles imparts very attractive and beautiful appearance to the final leather. Due to calcification of the skeleton, the stingray skin is very hard and tough and it is difficult to produce soft leathers by conventional leather processing. Hence, to aim at the preparation of soft leathers from stingray skins two different process technologies has been developed in the present study. Initially, the calciu m content present in the raw stingray skin has been determined by atomic absorption spectroscopy. To min imize the calciu m content and to impart fibre splitting a suitable modification has been made in the pickling and chrome tanning process. Histological and SEM investigations have been carried out to reveal the effect of tanning system on fibre separation resulting in softness. The proteoglycan content in stingray skin is comparatively more due to the presence of cartilag inous skeleton. Xylanase enzy me has been effectively used to acting upon this linear carbohydrate polymer thereby open up the rig id fibre structure. The stingray leathers with denticles have been used for the preparation of massage footwear where the denticles are used to stimulate the reflex points present in our soles during walking. Efforts have been made to utilize the leather with unique grain structure for the preparation of outer covers for steering wheel, motor bike handle, tennis racket and cricket bat handles where the encased stingray leather imparts more grip to the user and these products could also used to stimulate the reflex points present in our palms. Thus this paper will discuss about the process technologies for the preparation of soft leathers from stingray skins and their novel applications.
[Show abstract][Hide abstract] ABSTRACT: The present work reports the preparation of Poly L-Lactide (PLLA) and Curcumin loaded Poly L-Lactide (CPLLA) nanofibers by electrospinning. A series of PLLA solution (12 wt %) and C-PLLA (12 wt % PLLA) solution containing Curcumin (0.5 wt % and 1 wt %)) were electrospun into nanofibers. SEM images showed the average diameter of PLLA and C-PLLA in the range of 50–200 nm. The TEM images showed the dispersion of Curcumin on C-PLLA nanofibers. The XRD pattern indicated decreases of crystallinity with the increase in the amount of Curcumin. The characteristic peak of Curcumin was confirmed by FTIR. The TGA results showed the degradation of PLLA and C-PLLA close to 300 °C. The percentage porosity and the contact angle of PLLA were found to be 90.2 % and 115±3 ° with deionised water, respectively. The water uptake percentage was found to be 17.6 %. The percentage cumulative release of Curcumin at the end of 8th day for 0.5 and 1.0 wt % formulations was 81.4±1.3 and 86.7±1.7 % respectively. The in-vitro biological cytotoxicity studies were performed using C6 glioma cells and NIH 3T3 fibroblast by MTT assay and SEM analysis.
Full-text · Article · Sep 2012 · Fibers and Polymers
[Show abstract][Hide abstract] ABSTRACT: A chromium-keratin tanning compound has been prepared by treating chicken feathers with acidified dichromate. The newly developed chromium-keratin compound contain ~ 17% w/w Cr 2O 3 and protein content of ~10% w/w. The chromiumkeratin compound has been characterized using FT-IR, MALDI-TOF, EDX and computer aided color analysis. Tanning studies have been carried out with goat skins, where the chromium-keratin compound has been used as chrome tanning agent in place of basic chromium sulfate (BCS). The denaturation temperature of chromium-keratin tanned leather analyzed by DSC shows a value of 112°C and the percentage exhaustion of chromium in the tanning bath is greater than 80 percent. Structural and physical characteristics of chromiumkeratin compound treated leathers were analyzed using standard techniques and the results were compared with the control leathers tanned with commercial BCS.
No preview · Article · May 2012 · Journal- American Leather Chemists Association
[Show abstract][Hide abstract] ABSTRACT: Poly(caprolactone) (PCL) electrospun nanofibers were modified by aminolysis and collagen was immobilized on the aminolysed PCL nanofibers. Considering low immunogenic response collagen elicits, immobilization of the same is anticipated to enhance the tissue engineering application of the PCL nanofibers. Amino groups were introduced into PCL nanofibers through aminolysis process. Aminolysis of PCL nanofibers was confirmed by electron dispersive X-ray analysis (EDX). Collagen was immobilized on aminolysed PCL nanofibers using glutaraldehyde as crosslinker. The collagen crosslinking on to PCL nanofibers was established by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The fiber morphologies of PCL nanofibers at different stages were characterized by scanning electron microscopy (SEM). The change in hydrophobicity of PCL nanofibers due to aminolysis and collagen immobilization was determined by water contact angle measurements. Aminolysis followed by collagen immobilization had reduced the intrinsic hydrophobicity of PCL nanofibers. NIH 3T3 fibroblasts were cultured for 2 days on PCL nanofibers, aminolysed PCL nanofibers, and aminolysed PCL nanofibers crosslinked with collagen. Cell attachment and growth were observed by MTT assay in each case. Collagen immobilization improved the biocompatibility of the PCL nanofibers. Thus the modified PCL nanofibers can be used as suitable broad spectrum scaffold for skin, cartilage, bone, cardiac constructs for efficient tissue engineering applications.
[Show abstract][Hide abstract] ABSTRACT: Electrospinning is a desired method to produce ultrathin fibers for tissue engineering. In order to mimic the nanofibrous structure of the extracellular matrix (ECM) poly(propylene carbonate) ultrathin fibers were electrospun using N,N-dimethyl acetamide as solvent. Cationic surfactant, cetyl trimethyl ammonium bromide, was found to aid in the formation of beadless fibers of poly(propylene carbonate). Electrospinning parameters viz. concentration of polymer and that of the surfactant used as an additive, flow rate, electrostatic field, and effect of inner diameter of the needle were investigated and optimized. Scanning electron microscopy showed porous scaffold and fibers of diameter ranging from nano- to submicron range. FTIR spectroscopy and thermal analysis of the obtained fibers ensured the complete evaporation of solvent and optimal thermal stability of fibers for tissue engineering applications. The prepared fibers possess Young's modulus of 10.19 and 26.39 GPa with the tensile strengths of 22.11 and 21.29 MPa under dry and wet conditions, respectively. The fiber mat was measured to have a porosity of 48% and exhibited competent water retention capacity of 64%. Furthermore the scaffold was found to support the adhesion of mouse NIH 3T3 fibroblasts proving its mettle as a potential scaffold for tissue engineering applications.
[Show abstract][Hide abstract] ABSTRACT: Fabrication of keratin–collagen (KC) 3D scaffold with improved thermal denaturation rate is reported. In vitro application of (KC) scaffold stimulates basic extra cellular matrix constituents. KC Scaffold considerably reduced undesirable properties of both collagen and keratin while collagen incorporation reduces the fragility with increases of strength and flexibility in the scaffold. In addition to this, the scaffold showed homogenous well-interconnected pores in the range of 10–100 µm when observed in scanning electron microscope. Usage of keratin in KC scaffold offers increased biodegradation rate and higher denaturation rate in addition to its rapid cell growth with normal morphology ultimately reaching cell population of 3.9–9.7 million per cm3 after 48 hr in KC scaffold. Circular dichroism (CD) and Fourier transform spectroscopy (FT-IR) of KC showed presence of helical structure of collagen and ß-turns of keratin confirming retention of native structures of both the proteins KC scaffold showed good swelling behavior and water uptake. Our study strongly supports the superidity of KC scaffold over the collagen or keratin when they are independently used for tissue engineering applications.
Full-text · Article · Mar 2012 · Polymers for Advanced Technologies
[Show abstract][Hide abstract] ABSTRACT: In the present study, green and sustainable method or eco-friendly approaches to tanning process based on unnatural D-amino acids (D-AA)-aldehyde (Ald) as a substitute for chrome-free tanning has been attempted. The distribution of optically active D-AA in tanned leather, the hydrothermal stability, the mechanical properties and resistance to collagenolytic activity of tanned leather, the evaluation of eco-friendly characteristics were investigated. Scanning electron microscopic (SEM) and Atomic force microscopic (AFM) analyses indicate the surface morphology and roughness, respectively, of the tanned leather collagen matrix. Shrinkage and Differential scanning calorimetric (DSC) analyses shows that the shrinkage temperature (T(s)) and denaturation temperature (T(d)) of tanned leather are related to the content of D-AA+Ald present in the leather matrix. It has been found that the T(s) of D-AA tanned leather is more than that of Ald tanned leather and also more or less equal to chrome tanned leather. Environmental impact assessment (EIA) shows that the developed process results in significant reduction in total solids content (TSC) and improves better biodegradability of organic compound present in the effluent compared to chrome tanning.
No preview · Article · Feb 2012 · Journal of hazardous materials
[Show abstract][Hide abstract] ABSTRACT: We report fabrication of three dimensional scaffolds with well interconnected matrix of high porosity using keratin, chitosan and gelatin for tissue engineering and other biomedical applications. Scaffolds were fabricated using porous Keratin-Gelatin (KG), Keratin-Chitosan (KC) composites. The morphology of both KG and KC was investigated using SEM. The scaffolds showed high porosity with interconnected pores in the range of 20-100 mu m. They were further tested by FTIR, DSC, CD, tensile strength measurement, water uptake and swelling behavior. In vitro cell adhesion and cell proliferation tests were carried out to study the biocompatibility behavior and their application as an artificial skin substitute. Both KG and KC composite scaffolds showed similar properties and patterns for cell proliferation. Due to rapid degradation of gelatin in KG, we found that it has limited application as compared to KC scaffold. We conclude that KC scaffold owing to its slow degradation and antibacterial properties would be a better substrate for tissue engineering and other biomedical application.
Full-text · Article · Feb 2012 · Materials Science and Engineering C
[Show abstract][Hide abstract] ABSTRACT: Gingival recession (GR) can result in root sensitivity, esthetic concern to the patient, and predilection to root caries. The purpose of this randomized clinical study was to evaluate (1) the effect of guided tissue regeneration (GTR) procedure using a bioabsorbable collagen membrane, in comparison to autogenous subepithelial connective tissue graft (SCTG) for root coverage in localized gingival recession defects; and (2) the change in width of keratinized gingiva following these two procedures.
A total of 10 cases, showing at least two localized Miller's Class I or Class II gingival recession, participated in this study. In a split mouth design, the pairs of defects were randomly assigned for treatment with either SCTG (SCTG Group) or GTR-based collagen membrane (GTRC Group). Both the grafts were covered with coronally advanced flap. Recession depth (RD), recession width (RW), width of keratinized gingiva (KG), probing depth (PD), relative attachment level (RAL), plaque index (PI), and gingival index (GI) were recorded at baseline, 3 and 6 months postoperatively.
Six months following root coverage procedures, the mean root coverage was found to be 84.84% ± 16.81% and 84.0% ± 15.19% in SCTG Group and GTRC Group, respectively. The mean keratinized gingival width increase was 1.50 ± 0.70 mm and 2.30 ± 0.67 mm in the SCTG and GTRC group, respectively, which was not statistically significant.
It may be concluded that resorbable collagen membrane can be a reliable alternative to autogenous connective tissue graft in the treatment of gingival recession.
Full-text · Article · Oct 2011 · Journal of Indian Society of Periodontology
[Show abstract][Hide abstract] ABSTRACT: We report the detailed studies on the inhibitory effect of tannic acid (TA) on Clostridium histolyticum collagenase (ChC) activity against degradation of extracellular matrix component of collagen. The TA treated collagen exhibited 64% resistance against collagenolytic hydrolysis by ChC, whereas direct interaction of TA with ChC exhibited 99% inhibition against degradation of collagen and the inhibition was found to be concentration dependant. The kinetic inhibition of ChC has been deduced from the extent of hydrolysis of N-[3-(2-furyl) acryloyl]-Leu-Gly-Pro-Ala (FALGPA). This data provides a selective competitive mode of inhibition on ChC activity seems to be influenced strongly by the nature and structure of TA. TA showed inhibitor activity against the ChC by molecular docking method. This result demonstrated that TA containing digalloyl radical possess the ability to inhibit the ChC. The inhibition of ChC in gaining new insight into the mechanism of stabilization of collagen by TA is discussed.
No preview · Article · Aug 2011 · Journal of Enzyme Inhibition and Medicinal Chemistry
[Show abstract][Hide abstract] ABSTRACT: The irreversible destruction of extracellular matrix (ECM) such as cartilage, tendon, and bone that comprise synovial joints is the hallmark of both rheumatoid arthritis and osteoarthritis by over-expression of matrix metalloproteinase (MMP)-collagenases. We report herein the detailed study on the inhibitory effects of Withania somnifera extract (WSE) and Cardiospermum halicacabum extract (CHE) on Clostridium histolyticum collagenase (ChC) activity against the degradation of the ECM component of bovine Achilles tendon type I collagen by hydroxyproline assay method. Interaction of WSE and CHE with ChC exhibited 71% and 88% inhibition, respectively, to the collagenolytic activity of ChC against collagen degradation, and the inhibition was found to be concentration-dependent. The inhibition kinetics of ChC by both the extracts has been deduced from the extent of hydrolysis of N-[3-(2-furyl) acryloyl]-Leu-Gly-Pro-Ala. Both WSE and CHE are provided competitive and mixed type inhibition on ChC activity, respectively. Circular dichroism studies of ChC on treatment with WSE and CHE revealed changes in the secondary structure of collagenase. These results suggest that the WSE and CHE facilitated collagen stabilization through collagenase inhibition.
No preview · Article · Jul 2011 · Applied biochemistry and biotechnology
[Show abstract][Hide abstract] ABSTRACT: In this study, we report on physical and in vitro biological characterization of succinylated collagen (SC).
SC was prepared by succinylation of type I bovine tendon collagen. SC swells and dissolves in physiological
pH buffers (pH 7.4) Biocompatibility of SC to collagen for fibroblasts was comparable but L6 myoblasts
showed pronounced proliferation and differentiation with SC. Using the MALDI-TOF/MS
technique, SC was found with increased molecular mass by 16,359 Da per molecule which corresponds
to about 54 succinyl groups covalently linked to the collagen strand. Raman spectroscopy revealed the
retention of triple helical structure conformation in the presence of linked succinyl groups. New peaks
near 1737, 1675 and 1420 cm�1 and decreased intensities near 2440 and 488 cm�1 provides the most
convenient marker bands for succinylation of collagen. The intense band regions near 2856–2934,
2724, and 1445 cm�1 also confirms the existence of succinyl groups
Full-text · Article · May 2011 · Journal of Molecular Structure THEOCHEM
[Show abstract][Hide abstract] ABSTRACT: The collagen coated cholesterol (CH)-free liposome nanoparticle (CCLNP) matrix has been prepared and characterized for use
as therapeutic drug carriers, tissue engineering and regenerative medicinal applications. The CH-free liposome nanoparticle
(LNP) was prepared by heating method under the N2 atmosphere and CCLNP matrix was prepared by incubation of bovine Achilles
tendon collagen with preformed CH-free LNP. The results indicate that collagen stabilizes the original liposomal structure,
and CCLNP are more stable in vitro than control liposome. This mineralized collagen composite matrix could be useful to bone
and dental implants.
No preview · Article · Feb 2011 · Transactions of the Indian Institute of Metals