R Shelma

Publications of R Shelma

• Submicroparticles composed of amphiphilic chitosan derivative for oral insulin and curcumin release applications.

  Authors: R Shelma, Chandra P Sharma

  Colloids and surfaces. B, Biointerfaces. 08/2011; 88(2):722-8.

  Amphiphilic polymers for dual drug delivery have been a focus of research in recent years. We have previously developed and characterized Lauroyl sulphated chitosan (LSCS). Here biologicalAmphiphilic polymers for dual drug delivery have been a focus of research in recent years. We have previously developed and characterized Lauroyl sulphated chitosan (LSCS). Here biological characterizations like mucoadhesion, cytotoxicity, calcium binding, tight junction opening and enzymatic degradation studies were performed to understand its applicability. In vitro drug release properties of both hydrophilic insulin and hydrophobic curcumin were carried out. The biological activity and stability of released insulin were also studied. The stability studies of encapsulated curcumin and uptake studies have also been carried out. LSCS showed strong mucoadhesion and 100% of non-toxicity. LSCS could transiently open tight junctions between Caco-2 cells and thus increase the paracellular permeability. LSCS enhanced calcium binding properties and decreased enzymatic degradation rate retaining insulin activity. LSCS could protect curcumin from photodegradation and could also enter into the cells. From release studies, LSCS was found to be a suitable candidate for both drugs.

• Development of lauroyl sulfated chitosan for enhancing hemocompatibility of chitosan.

  Authors: R Shelma, Chandra P Sharma

  Colloids and surfaces. B, Biointerfaces. 02/2011; 84(2):561-70.

  Chitosan (CS) has received much attention as a functional biopolymer especially in pharmaceutical applications, but has serious limitations owing to its poor hemo-compatibility property. PresentChitosan (CS) has received much attention as a functional biopolymer especially in pharmaceutical applications, but has serious limitations owing to its poor hemo-compatibility property. Present paper focuses on the chemical modification of CS in order to enhance hemocompatibility. Amphiphilic derivative (lauroyl sulfated chitosan, LSCS) was prepared by the inclusion of sulfo group (hydrophilic) and lauroyl group (hydrophobic) to CS backbone and particles were prepared by an ionic-gellation approach. Modification was confirmed by FTIR, NMR and zeta potential measurements and the microparticles were evaluated for its particle size, swelling properties and thermal behaviour. Blood compatibility studies like hemolysis, RBC, WBC, platelet aggregation studies, blood clotting time, protein adsorption and C3 protein depletion assay were carried out for these polymers using standard techniques and cytotoxicity studies were performed to understand its applicability. Negatively charged (-6.06 mV) LSCS submicroparticles (886 nm) were prepared in this study. Blood compatibility studies demonstrated that the amphiphilic modification improved the hemocompatibility of CS. RBC aggregation and hemolysis induced by CS were significantly reduced by this modification. Further amphiphilic modification was effective in reducing the protein adsorption on CS. LSCS derivatives were found to be non-toxic in L929 cell lines. From these studies, it appears that LSCS is a hemocompatible version of CS.

• Acyl modified chitosan derivatives for oral delivery of insulin and curcumin.

  Authors: R Shelma, Chandra P Sharma

  Journal of materials science. Materials in medicine. 04/2010; 21(7):2133-40.

  In the present investigation, bioadhesive property of chitosan (CS) was enhanced by the N-acylation with hexanoyl, lauroyl and oleoyl chlorides. The chemical structure of the modified polymer wasIn the present investigation, bioadhesive property of chitosan (CS) was enhanced by the N-acylation with hexanoyl, lauroyl and oleoyl chlorides. The chemical structure of the modified polymer was characterized by FTIR and zeta potential measurements. The swelling ability was evaluated at alkaline pH. Mucin interactions and mucoadhesion experiments were performed under in vitro experimental conditions. Cytotoxicity experiments were employed to confirm the applicability of these particles as drug carriers. Finally in vitro evaluation of hydrophobic and hydrophilic drug release profile at acidic and alkaline pH was also conducted. A strong interaction between CS acyl derivatives and mucin was detected, which was further confirmed by an in situ mucoadhesion experiments with excised intestinal tissue. CS modified with oleoyl chloride showed better mucoadhesion property, as compared to the one modified with lower fatty acid groups. CS derivatives were found non-toxic on L-929 cell lines and provided sustained release of hydrophobic drugs under in vitro experimental conditions. From these studies it seems that hydrophobically modified CS is an interesting system for drug delivery applications.

• Characterization of surface modified polyester fabric.

  Authors: Roy Joseph, R Shelma, A Rajeev, C Muraleedharan

  Journal of materials science. Materials in medicine. 07/2008;

  Woven polyethylene terephthalate (PET) fabric has been used in the construction of vascular grafts and sewing ring of prosthetic heart valves. In an effort to improve haemocompatibility and tissueWoven polyethylene terephthalate (PET) fabric has been used in the construction of vascular grafts and sewing ring of prosthetic heart valves. In an effort to improve haemocompatibility and tissue response to PET fabric, a fluoropolymer, polyvinylidine fluoride (PVDF), was coated on PET fabric by dip coating technique. The coating was found to be uniform and no significant changes occurred on physical properties such as water permeability and burst strength. Cell culture cytotoxicity studies showed that coated PET was non-cytotoxic to L929 fibroblast cell lines. In vitro studies revealed that coating improved haemocompatibility of PET fabric material. Coating reduced platelet consumption of PET fabric by 50%. Upon surface modification leukocyte consumption of PET was reduced by 24%. About 60% reduction in partial thromboplastin time (PTT) observed when PET was coated with PVDF. Results of endothelial cell proliferation studies showed that surface coating did not have any substantial impact on cell proliferation. Overall results indicate that coating has potential to improve haemocompatibility of PET fabric without affecting its mechanical performance.

• Development and characterization of self-aggregated nanoparticles from anacardoylated chitosan as a carrier for insulin

  Authors: R. Shelma, Willi Paul, Chandra P. Sharma

  Carbohydrate Polymers.

  Nanoparticulate carriers made from biodegradable polymers especially from chitosan seems to be an excellent approach to increase the uptake and transport of orally administered insulin. VariousNanoparticulate carriers made from biodegradable polymers especially from chitosan seems to be an excellent approach to increase the uptake and transport of orally administered insulin. Various approaches have been studied to develop nanoparticles from chitosan including self-aggregated nanoparticles from hydrophobically modified chitosan. Anacardic acid is a naturally occurring fatty acid having bulky aromatic group as well as long aliphatic chain and an amphiphilic monomer of great potential. An attempt has been made to develop and characterize self-aggregated nanoparticles from chitosan modified with anacardic acid. Anacardoylated chitosan spontaneously formed nanoparticles in aqueous insulin solution with a particles size of 214 nm diameter at neutral pH. The hydrophobic nature of the nanoparticles helped in the sustained release of insulin in the intestinal environment and the released insulin was stable and retained its conformation. However, it released insulin in acidic conditions and need to be encapsulated in alginate to render pH sensitiveness.

• Characterization of surface modified polyester fabric

  Authors: R Joseph, R Shelma, A Rajeev, CV Muraleedharan

  Journal of Materials Science: Materials in Medicine. 20:153-159.