Determination of pepsin by capillary electrophoresis using mixed polymer coated capillary with switchable properties toward protein adsorption/desorption

Abstract

In this work, a simple online preconcentration method for quantitative detection of pepsin was realized by using the binary mixed polymer brushes coated capillary with switchable properties toward protein adsorption. Firstly, the binary mixed polymer brushes were prepared by grafting poly(2‐methyl‐2‐oxazoline) and poly(4‐vinylpyridine) onto the inner wall of the capillary through a polydopamine anchor. Then the coatings were characterized by X‐ray photoelectron spectrometer and electroosmotic flow measurement. The results indicated that the composition of coating could be controlled by varying the feed ratio of poly(2‐methyl‐2‐oxazoline) to poly(4‐vinylpyridine) and the inner surface charge could be tuned toward the change of pH and ionic strength. The results showed that when the poly(2‐methyl‐2‐oxazoline)/poly(4‐vinylpyridine) mass ratio was 80/20, the highest online preconcentration effect was obtained and the sensitivity enhancement factor was 6.3. Moreover, satisfactory sensitivity (limit of detection: 7.5 ng/mL) and good repeatability were obtained with the online preconcentration method. The polymer‐coated capillary was still stable for online preconcentration and detection of pepsin after 50 consecutive runs. Last, the proposed method was used successfully to online preconcentrate pepsin in the saliva matrix.

Capillary Electrophoresis: A Three-Year Literature Review

“…Capillaries coated with special functional materials may serve specific purposes . For example, a MIP coated capillary can be used for online preconcentration and selective determination of trace analytes in real samples .…”

Capillary electrophoresis‐mass spectrometry for intact protein analysis: Pharmaceutical and biomedical applications (2018–March 2023)

“…Successive multiple ionic polymer layers coating, which combines alternating polycationic and polyanionic polymer layers boosting the durability of the coating, was successfully used in several recent publications [122][123][124][125][126], however, more studies are needed to investigate the performance of successive multiple ionic polymer layers for CE-MS top-down proteomics. An interesting approach for on-line preconcentration of proteins through switchable protein adsorption/desorption properties of mixed polymer brushes coatings was applied for on-line preconcentration of lysozyme in hen egg white [127,128], bovine serum albumin [129] and pepsin [130]. The achieved LOD of lysozyme was 4.5 pg/ml, which represents 100 000 times lower LOD compared to an uncoated capillary.…”