Enrichment and separation of acidic and basic proteins using the centrifugal ultrafiltration followed by nanoparticle‐filled capillary electrophoresis

Abstract

This report describes a method for enrichment and separation of acidic and basic proteins using the centrifugal ultrafiltration followed by nanoparticle-filled capillary electrophoresis. To improve stacking and separation efficiencies of proteins, the separation buffer containing 1.6% poly(diallyldimethylammonium chloride) was added with gold nanoparticles (AuNP), poly(ethylene oxide), cetyltrimethylammonium bromide, and poly(vinyl alcohol). As a result, the use of AuNP as additives exhibited better efficiency in separation, stacking, and analysis time. Even for large-volume samples (110 nL), the separation efficiencies of acidic and basic proteins remained greater than 10(4) and 10(5) plates/m, respectively. To further enhance detection sensitivity, protein samples were enriched using the centrifugal ultrafiltration, followed by our proposed stacking method. The detection sensitivity was improved up to 314-fold compared to normal hydrodynamic injection. Additionally, the limits of detection at a signal-to-noise of 3 for most proteins were down to nanomolar range. We have validated the application of our method by means of analyses of 50 nM lysozyme in saliva samples. The proposed method was also successfully applied to the analyses of egg-white proteins, which have large differences in molecular weight and pI.

Selected applications of calixarene derivatives

“…pharmaceutical, 78 food 79 or biochemistry 80 solid-phase microextraction (SPME) is used. This is an efficient extraction technique enabling simultaneous extraction and preconcentration of aqueous, gaseous and solid matrices.…”

Application of gold nanoparticles in separation sciences

“…Transmission electron microscopy (TEM) is a powerful and straightforward method for the determination of size (in several studies including size distribution) and shape of NPs 34. It has been used for characterization of GNPs in most of the below cited applications of GNPs in separation sciences 35–60. The advantage of this method stems from relatively direct observation of the real morphological shape and size of NPs and the capability of detailed analysis of digitized photographs utilizing software for image analysis.…”

Food analysis: A continuous challenge for miniaturized separation techniques

“…In the field of food quality, in recent years, CE has been a fundamental technique broadly applied for the analysis of protein profiles, proteins, amino acids, immunoglobulins and peptides 55–74 and antioxidant compounds 75–89. To a lesser extent, it has also been useful for the determination of organic acids 90–96, inorganic ions 97–99, carbohydrates 100–103 and other compounds such as salicylaldehyde 104, sorbate and benzoate 105, folic acid 106, saccharine and aspartame 107, glucosinolates 108 and water‐soluble vitamins 109 in different kinds of food matrices.…”