title: Size-dependent optical properties of bio-compatible ZnS:Mn nanocrystals and their application in the immobilisation of trypsin.
abstract: Chitosan capped zinc sulphide nanocrystals doped with manganese (ZnS:Mn) have been synthesised by chemical capping co-precipitation method and structurally characterised by XRD, TEM and EDXS techniques. The dependence of optical properties on the size of these bio-compatible ZnS:Mn nanocrystals was investigated by UV/Vis and photoluminescence (PL) spectroscopic techniques in aqueous solvents. A variation in molar concentration of the precursor, sodium sulphide, from 0.125 to 0.01 mol L(-1) is accompanied by a decrease in particle size. The excitonic peak in the UV/Vis spectra is found to be blue shifted with a decrease in size of the nanocrystals due to confinement effects. In the present study, trypsin was immobilised onto ZnS:Mn nanocrystals using glutaraldehyde (GA) as cross-linker, which was confirmed by photoluminescence (PL) and Fourier transform infrared (FTIR) spectroscopic studies. Results indicate that the activity of trypsin, immobilised onto chitosan modified nanocrystals, has improved upon cross-linking, which suggests that the immobilised trypsin has become more stable and active. This work highlights the prospects of potential applications of immobilised trypsin in therapeutic and diagnostic fields.
authors.affiliation: Department of Physics, Cochin University of Science and Technology, Kochi 682 022, Kerala, India. sajimollazar@gmail.com
authors.forename: M
authors.initials: M
authors.lastname: Sajimol Augustine
authors.forename: P P
authors.initials: PP
authors.lastname: Manzur Ali
authors.forename: K
authors.initials: K
authors.lastname: Sapna
authors.forename: K K
authors.initials: KK
authors.lastname: Elyas
authors.forename: S
authors.initials: S
authors.lastname: Jayalekshmi
mesh_terms: D000042:Absorption; D001672:Biocompatible Materials / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry; D004800:Enzymes, Immobilized / Q000378:metabolism; D008345:Manganese / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D055620:Optical Phenomena; D010316:Particle Size; D017550:Spectroscopy, Fourier Transform Infrared; D013440:Sulfides / Q000737:chemistry*; D014357:Trypsin / Q000378:metabolism*; D014961:X-Ray Diffraction; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D004800:Enzymes, Immobilized; D013440:Sulfides; D017967:Zinc Compounds; D008345:Manganese; D048271:Chitosan; D014357:Trypsin; C031238:zinc sulfide