In this work, a simple method for alcohol synthesis with high enantiomeric purity was proposed. For this, colloidal gold and silver surface modifications with 3-mercaptopropanoic acid and cysteamine were used to generate carboxyl and amine functionalized gold and silver nanoparticles of 15 and 45 nm, respectively. Alcohol dehydrogenase from Thermoanaerobium brockii (TbADH) and its cofactor (NADPH) were physical and covalent (through direct adsorption and using cross-linker) immobilized on nanoparticles' surface. In contrast to the physical and covalent immobilizations that led to a loss of 90% of the initial enzyme activity and 98% immobilization, the use of a cross-linker in immobilization process promoted a loss to 30% of the initial enzyme activity and >92% immobilization. The yield of NADPH immobilization was about 80%. The best results in terms of activity were obtained with Ag-citr nanoparticle functionalized with carboxyl groups (Ag-COOH), Au-COOH(CTAB), and Au-citr functionalized with amine groups and stabilized with CTAB (Au-NH₂(CTAB)) nanoparticles treated with 0.7% and 1.0% glutaraldehyde. Enzyme conformation upon immobilization was studied using fluorescence and circular dichroism spectroscopies. Shift in ellipticity at 222 nm with about 4 to 7 nm and significant decreasing in fluorescence emission for all bioconjugates were observed by binding of TbADH to silver/gold nanoparticles. Emission redshifting of 5 nm only for Ag-COOH-TbADH bioconjugate demonstrated change in the microenvironment of TbADH. Enzyme immobilization on glutaraldehyde-treated Au-NH₂(CTAB) nanoparticles promotes an additional stabilization preserving about 50% of enzyme activity after 15 days storage. Nanoparticles attached-TbADH-NADPH systems were used for enantioselective (ee > 99%) synthesis of (S)-7-hydroxy-2-tetralol.

Nowadays, due to a wide range of applications of nanoparticles (NPs) in many industrial areas, accumulations of those entities in environment pose a great risk. Owing to their inertness, noble metal NPs may remain in contaminated soils nearly unchanged for long time. Within this context, size-, shape-, and concentration-dependent uptake of particles by plants belongs to unexplored area. In this work, we present water solutions of biologically friendly synthesized spherical AuNPs with pretty narrow size distribution in size range from 10 to 18 nm. Their thorough characterization by atomic absorption spectroscopy, mass spectroscopy-equipped inductively coupled plasma, dynamic light scattering (DLS), and TEM methods was followed by the study of their effect on the growth of Arabidopsis thaliana (primary and lateral roots), in particle size- and concentration-dependent manner. Due to strictly round-shape form of AuNPs and absence of particle agglomeration, DLS-derived size and size distribution were in good concordance with those obtained from TEM. The length and number of A. thaliana lateral roots were significantly affected by all types of AuNPs. Smallest AuNPs at highest concentration inhibited length of primary roots and, in contrast, enhanced hair root growth.