Potential of silk sericin based nanofibrous mats for wound dressing applications.

Wound dressing developed using bioactive materials has been a current area of research for treating chronic non-healing wounds owing to its high demand. Here, we report the fabrication and evaluation of nanofibrous matrix based wound dressings using biopolymer poly(vinyl alcohol) (PVA) incorporated with silk sericin (SS). SS extracted from the cocoons of mulberry variety Bombyx mori and non-mulberry variety Antheraea assama has been used to develop two types of blended mats. Herein, SS based nanofibrous dressings fabricated using electrospinning technique were thoroughly characterized and evaluated for wound healing applications. The developed SS based nanofibrous mats ranged from 130 to 160 nm in diameter with micro to nanoporous structure. The dressings were endowed with free radical scavenging capacity, antibacterial activity, swelling capacity, and biocompatibility due to incorporation of SS. Furthermore, murine fibroblasts (L929) and human keratinocytes (HaCaT) cultured on the PVA-SS blended mats showed higher proliferation as compared to pristine PVA mats as observed over a period of 14 days (p ≤ 0.01). The blended mats also showed spread out morphology of cells in comparison to spherical clumps formed on PVA mats. In addition, SS from both silk types exhibited excellent antioxidant potential without hampering the cell viability even under H2O2 driven oxidative stress. Moreover, SS (both types) released from the nanofibrous mats also healed the wounds at thrice the rate of control under in vitro conditions. Furthermore, subcutaneous implantation of nanofibrous mats in mice showed in vivo tolerance of the blended nanofibrous mats observed over four weeks without eliciting any inflammatory reactions to the host tissue. Taken together, the developed silk sericin-based dressings signify an attractive substrate for treatment of chronic wounds like diabetic foot ulcers.

Reloadable Silk-Hydrogel Hybrid Scaffolds for Sustained and Targeted Delivery of Molecules.

Tunable repeated drug administration is often inevitable in a number of pathological cases. Reloadable 3D matrices for sustained drug delivery are predicted as a prospective avenue to realize this objective. This study was directed toward sonication-induced fabrication of novel reloadable Bombyx mori silk fibroin (SF) (4, 6, and 8 wt %) hydrogel, injected within 3D porous (8 wt %) scaffolds. The focus was to develop a dual-barrier reloadable depot system for sustained molecular cargo release. Both the varying SF concentration (4, 6, and 8 wt %) and the sonication time (30, 45, and 60 s) dictated the extent of cross-linking, ß-sheet content, and porosity (1-10 µm) influencing the release behavior of model molecules. Release studies of model molecules (trypan blue, TB, 961 Da and bovine serum albumin, BSA, 66 kDa) for 28 days attested that the variations in their molecular weight, the matrix cross-linking density, and the scaffold-hydrogel interactions dictated the release behavior. The Ritger and Peppas equation was further fitted into the release behavior of model molecules from various SF matrices. The hybrid constructs exhibited high compressive strength along with in vitro compatibility using primary porcine chondrocytes and tunable enzymatic degradation as assessed for 28 days. The aptness of the constructs was evinced as a reloadable model molecule (BSA and fluorescein isothiocyanate-inulin, 3.9 kDa) depot system through UV-visible and fluorescence spectroscopic analyses. The novel affordable platform developed using silk scaffold-hydrogel hybrid constructs could serve as a sustained and reloadable drug depot system for administration of multiple and repeated drugs.

Analysis of Jatropha curcas transcriptome for oil enhancement and genic markers.

Oil-rich seeds of Jatropha curcas are being focussed as a source of bio-diesel. However, prior to its industrial use, a lot of crop improvement efforts are required in Jatropha. Availability of a large number of EST sequences of Jatropha in public domain allow identification of candidate genes for several agronomic characters including oil content in seeds. Here, we have analysed 42,477 ESTs of Jatropha spanning 22.9 Mbp for microsatellites and fatty acid metabolism related sequences. Unigene sequences were built using CAP 3 programme resulted in 12,358 contigs and 5,730 singlets. Nearly, 8 % unigenes showed presence of microsatellites, slightly over-represented compared to their occurrence in ESTs. Most of the microsatellites were either di- or tri-nucleotide repeats, while other categories of tetra-, penta- and hexa-nucleotide repeats together constituted ~4 % of total microsatellites. Assessment of functional relevance of unigenes was carried out using Blast2GO using its default settings. The overall sequence similarity level against sequences in 'nr' database was >80 %. A total of 931 sequences that participated in any of the pathways related to fatty acid or lipid metabolism were found at GO level 6. Among these, GO terms "Fatty acid metabolic process" and "Fatty acid biosynthetic process" were most over-represented. Overall, our work has due relevance in identifying molecular markers for the candidate genes for oil content in Jatropha seeds, and will prove to be an important reference for further studies for identification of trait specific markers in Jatropha.