Ultrasensitive surface-enhanced Raman scattering detection of trypsin based on anti-aggregation of 4-mercaptopyridine-functionalized silver nanoparticles: an optical sensing platform toward proteases

Abstract

In this work, a simple and sensitive surface-enhanced Raman scattering (SERS) strategy was developed for recognition and detection of trypsin, by using anti-aggregation of 4-mercaptopyridine (4-MPY)-functionalized silver nanoparticles (AgNPs) based on the interaction between protamine and trypsin.The polycationic protamine not only served as a substrate for enzyme hydrolysis but also worked as a medium for SERS enhancement, which could bind negatively charged 4-MPY-functionalized AgNPs and induce their aggregation. The hydrolysis catalyzed with trypsin in sample solution decreased the concentration of free protamine, resulting in the dispersion of AgNPs and thus decreasing the Raman intensity of 4-MPY, by which the trypsin could be sensed optically. A detection level down to 0.1 ng mL À1 for trypsin was obtained. The induced accumulation of AgNPs modified with Raman reporter 4-MPY largely enhanced the SERS responses. A good linearity was found within the wide range over five orders of magnitude and reasonable relative standard deviations (between 2.4 and 11.6%) were attained. By using trypsin as a model, the new concept can provide an excellent platform for ultrasensitive SERS measurements of various proteases/enzymes which can lead to nanoparticles stability change through catalyzed hydrolysis toward substrate.

Nanomaterial-based optical sensors for sensitive detection of heavy metal ions

“…Hence, substantial efforts have been devoted toward the design of various chemo/biosensors to identify and quantify proteases. In this section, we developed an effective SERS strategy for the detection of trypsin based on anti-aggregation of 4-MPY-AgNPs with the aid of polycationic protamine [22]. Schematic representation of the proposed SERS sensing principle for detection of trypsin was shown in Fig.…”

“…A) Schematic representation of the proposed SERS sensing principle for trypsin detection and (B) Raman spectra of (a) AgNPs, (b) 4-MPY, (c) protamine, (d) AgNPs + 4-MPY, (e) AgNPs + protamine, (f) 4-MPY + protamine, (g) AgNPs + 4-MPY + protamine + trypsin and (h) AgNPs + 4-MPY + protamine[22].…”

Qualitative and quantitative determination of coumarin using surface-enhanced Raman spectroscopy coupled with intelligent multivariate analysis

“…[25][26][27][28][29] SERS has been explored for wide application in bio-medicine, chemical and material analysis, and environmental monitoring. [30][31][32][33][34] The mechanism of SERS enhancement includes electromagnetic enhancement (EM) and chemical enhancement (CM). [35][36][37][38] Several researchers have shown that the electromagnetic enhancement factor is about 10 4 and the chemical enhancement contributes to an average enhancement factor of 100.…”

A simple fluorescent probe based on a pyrene derivative for rapid detection of protamine and monitoring of trypsin activity

“…Traditional methods for trypsin detection include enzymelinked immunosorbent assay 12 , gel electrophoresis 13 and radioimmunoassay 14 , while many new approaches have been developed in recent years, such as electrochemical assay 15 , quartz crystal microbalance (QCM) sensor 16 , surface-enhanced Raman scattering (SERS) 17 , optical detection based on nanomaterials and organic fluorescent probes 18 . Among them, fluorescent approaches have been widely used because of their simple operation, high sensitivity and ease of observation.…”