Cat IgG (Fab'2) [HRP]

A highly sensitive quantum dot (QD)-based western blot assay with extended dynamic range was developed. Bimodal size distribution QD (BQ) immunoprobes composed of small size single QD (7.3 nm) and big size QD nanobead (QB) (82.9 nm) were employed for fluorescent western blot immunoassay on a membrane. Small size QD immunoprobes contributed to wider dynamic range of assay, while big size QB immunoprobes provided higher detection sensitivity. This BQ-based western blot assay can achieve a wide dynamic range (from 7.8 to 4000 ng IgG) and is nearly as sensitive as commercial available ultrasensitive chemiluminescent methods, just using a simple gel imager with UV light (365 nm) excitation and red light filter (610 nm). The fluorescent signals of BQ western blot were stable for 10 min, while chemiluminescent signals faded after 1 min. Moreover, this BQ immunoprobe was utilized for the detection of housekeeping protein and specific target proteins in complex cell lysate samples. The limit of detection of housekeeping protein is 0.25 mu g of cell lysate, and the signal intensities were proportional to loading protein amount in a wide range from 0.61 to 80 mu g. We believe that this new strategy of bimodal size distribution nanoparticles can also be expanded for other functional nanoparticle-based biological assays to improve the sensitivity and extend the dynamic range.Graphical abstract

Bovine whey is an important ingredient in human nutrition and contains many biofunctional, glycosylated proteins. Knowledge on the glycoprotein composition of whey and whey products is valuable for the dairy industry. This paper describes a method for the characterisation of whey, or whey powders, by N-linked glycoprofile analysis. Application of the method for analysis of whey protein products showed clear differences in glycoprotein composition between concentrate, isolate and demineralised whey powders. The quantitative potential was explored by screening 100 pooled farm milk samples. IgG and lactoferrin protein concentrations determined by N-glycoprofile analysis matched well with ELISA results. The protein concentration of GIyCAM-1 was determined to be >= 1 mg mL(-1). The approaches presented in this work allow simultaneous concentration estimation of the three major whey glycoproteins, lactoferrin, IgG and GIyCAM-1 on the basis of their N-linked glycoprofiles, also in highly processed samples where conventional methods of detection (ELISA) are less suitable. (C) 2020 The Authors. Published by Elsevier Ltd.