ABSTRACT
The development of innovative drug delivery systems, versatile to different drug characteristics with better effectiveness and safety, has always been in high demand. Chitosan, an aminopolysaccharide, derived from natural chitin biomass, has received much attention as one of the emerging pharmaceutical excipients and drug delivery entities. Chitosan and its derivatives can be used for direct compression tablets, as disintegrant for controlled release or for improving dissolution. Chitosan has been reported for use in drug delivery system to produce drugs with enhanced muco-adhesiveness, permeation, absorption and bioavailability. Due to filmogenic and ionic properties of chitosan and its derivative(s), drug release mechanism using microsphere technology in hydrogel formulation is particularly relevant to pharmaceutical product development. This review highlights the suitability and future of chitosan in drug delivery with special attention to drug loading and release from chitosan based hydrogels. Extensive studies on the favorable non-toxicity, biocompatibility, biodegradability, solubility and molecular weight variation have made this polymer an attractive candidate for developing novel drug delivery systems including various advanced therapeutic applications such as gene delivery, DNA based drugs, organ specific drug carrier, cancer drug carrier, etc.
Subject(s)
Chitosan/chemistry , Drug Delivery Systems , Excipients/chemistry , Polymers/chemistryABSTRACT
Spillage of furnace oil is a more frequent event in recent times. In this study, environmental samples from furnace oil spillage sites of the Shela River, the Sundarbans, Bangladesh, were collected after three weeks of spillage. Serial dilution was applied and total seven bacterial isolates were separated as pure cultures. The oil-degrading potentiality of all seven isolates was further assessed, confirmed and compared with the growth pattern in furnace oil supplemented media, 2, 6-dichlorophenolindophenol test, and gravimetric analysis. After 7 days of incubation, isolates SS3, RW2, and SB degraded 56%, 43%, and 52% of supplemented furnace oil, respectively. The top three hydrocarbonoclastic bacterial isolates were selected as potential and identified as Pseudomonas aeruginosa (SS3), Bacillus sp. (RW2), and Serratia sp. (SB). All three isolates showed significant oil-degrading capacity compared to negative control, when incubated in sterile pond water supplemented with 2% furnace oil, suggesting them as potential bioremediation agents.
ABSTRACT
The rocG gene encoding glutamate dehydrogenase from Bacillus subtilis (Bs-GluDH) was cloned, and expressed at considerable magnitude in Escherichia coli. The recombinant Bs-GluDH was purified to homogeneity and has been determined to have a hexameric structure (M(r) 270 kDa) with strict specificity for 2-oxoglutarate and L-glutamate, requiring NADH and NAD+ as cofactors respectively. The enzyme showed low thermostability with T(m) = 41 degrees C due to dissociation of the hexamer. To improve the thermostability of this enzyme, we performed error-prone PCR, introducing random mutagenesis on cloned GluDH. Two single mutant enzymes, Q144R and E27F, were isolated from the final mutant library. Their T(m) values were 61 degrees C and 49 degrees C respectively. Furthermore, Q144R had a remarkably high k(cat) value (435 s(-1)) for amination reaction at 37 degrees C, 1.3 times higher than that of the wild-type. Thus, Q144R can be used as a template gene to modify the substrate specificity of Bs-GluDH for industrial use.
