Green tea catechin loaded niosomes: formulation and their characterization for food fortification.

The main aim of this study was to deliver green tea catechins with enhanced bioavailability using niosomal system. Catechins-loaded niosomes were prepared using food grade surfactant, Tween 60 and membrane stabilizers namely, lauryl alcohol, cetyl alcohol and cholesterol by thin film hydration technique. Catechins-loaded niosomes exhibited a hydrodynamic diameter of 58.48 nm with a narrow size distribution (PDI = 0.13) and zeta potential of - 31.75 mV, suggestive for homogeneity and good stability. Niosomes entrapped about 85.82% of catechin and showed sustained release under simulated GI conditions. Morphology of niosomal vesicles were carried out using scanning electron microscopy-energy X-ray dispersion spectroscopy, transmission electron microscopy and atomic force microscopy. Fourier-transform infrared spectroscopy and High-performance liquid chromatography analysis confirmed successful encapsulation of catechins. Antioxidant activity of catechins was retained in the niosomal form. Fortification of milk with catechins loaded niosomes showed no significant changes on sensory, physicochemical properties and exhibited higher antioxidant property.

Preparation of Casein Biopeptide-Loaded Niosomes by High Shear Homogenization and Their Characterization.

The aim of this study was to develop a niosomal system to deliver milk bioactive peptides with potential for enhanced bioavailability. Milk casein was hydrolyzed with Flavourzyme, and the hydrolysates were ultrafiltered to obtain low-molecular-weight peptides with enhanced antioxidant activity. Biopeptide-loaded niosomes were prepared by a high shear homogenization method. Peptide-loaded niosomes exhibited a mean particle size of 37.64 ± 0.98 nm with narrow size distribution (PDI = 24.66 ± 0.008%) and high zeta potential (-23.36 mV). The niosomes encapsulated about 67% of peptides into the vesicles and showed controlled and sustained release under simulated gastrointestinal conditions as compared to free peptides. The antioxidant activity of the peptides was not affected due to their encapsulation into niosomes. Morphology of peptide-loaded niosomes was determined by scanning electron microscopy, transmission electron microscopy and atomic force microscopy, and the microstructural interactions analyzed by Fourier transform infrared clearly indicated the formation of peptide-loaded niosomes. High-performance liquid chromatography spectra of peptides in the niosomes and the free peptides were similar, thus confirming their entrapment into the niosomes.

Rapid screening test for detection of oxytetracycline residues in milk using lateral flow assay.

A rapid, semi-quantitative lateral flow assay (LFA) was developed to screen the oxytetracycline (OTC) antibiotics residues in milk samples. In this study a competitive immuno-assay format was established. Colloidal gold nano-particles (GNP) were prepared and used as labelling material in LFA. Polyclonal antibodies were generated against OTC molecule (anti-OTC), purified and the quality was assessed by enzyme linked immuno sorbet assay. For the first time membrane components required for LFA in milk system was optimized. GNP and anti-OTC stable conjugate preparation method was standardized, and then these components were placed over the conjugate pad. OTC coupled with carrier protein was placed on test line; species specific secondary antibodies were placed on the control line of the membrane matrix. Assay was validated by spiking OTC to antibiotic free milk samples and results could be accomplished within 5min. without need of any equipment. The visual detection limit was 30ppb.

Synthesis and application of cephalexin imprinted polymer for solid phase extraction in milk.

Molecular imprinted polymer (MIP) against cephalexin was synthesized by co-polymerization of functional monomer, cross-linker, radical initiator, along with target molecule (cephalexin) in a porogenic material. Binding of cephalexin towards prepared MIP was studied in different solvents (water, methanol, 1M NaCl, acetone and acetonitrile) and best binding was observed in methanol. Partition coefficient and selectivity of prepared imprint and non-imprint was also studied. Cross reactivity in terms of binding efficiency was also assessed with other antibiotics. Chromatographic study of MIP was carried out by packing prepared imprint into glass column. MIP was used as matrix in solid phase extraction (SPE) for recovery of cephalexin from spiked milk samples for further estimation by high performance liquid chromatography. No interference was observed from milk components after elution of cephalexin from MIP, indicating selectivity and affinity of MIP. On the other hand, interference was observed in eluate obtained from C18 SPE column.