Sensitive colorimetric assays for α-glucosidase activity and inhibitor screening based on unmodified gold nanoparticles.
A colorimetric sensor has been developed in this work to sensitively detect α-glucosidase activity and screen α-glucosidase inhibitors (AGIs) utilizing unmodified gold nanoparticles (AuNPs). The sensing strategy is based on triple-catalytic reaction triggered by α-glucosidase. In the presence of α-glucosidase, aggregation of AuNPs is prohibited due to the oxidation of cysteine to cystine in the system. However, with addition of AGIs, cysteine induced aggregation of AuNPs occurs. Thus, a new method for α-glucosidase activity detection and AGIs screening is developed by measuring the UV-vis absorption or visually distinguishing. A well linear relation is presented in a range of 0.0025-0.05 U mL(-1). The detection limit is found to be 0.001 U mL(-1) for α-glucosidase assay, which is one order of magnitude lower than other reports. The IC50 values of four kinds of inhibitors observed with this method are in accordance with other reports. The using of unmodified AuNPs in this work avoids the complicated and time-consuming modification procedure. This simple and efficient colorimetric method can also be extended to other enzymes assays.
Laboratory of Biosensing Technology, School of Life Sciences, Shanghai University, Shanghai 200444, PR China.
Hongxia
H
Chen
Laboratory of Biosensing Technology, School of Life Sciences, Shanghai University, Shanghai 200444, PR China.
Jiangjiang
J
Zhang
Laboratory of Biosensing Technology, School of Life Sciences, Shanghai University, Shanghai 200444, PR China.
Heng
H
Wu
Institute of General Education, Pusan National University, Pusan 609-735, Republic of Korea.
Kwangnak
K
Koh
Department of Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, PR China. Electronic address: ym.yin@hotmail.com.
Yongmei
Y
Yin
D003124:Colorimetry / Q000379:methods*; D004353:Drug Evaluation, Preclinical / Q000379:methods; D057075:Enzyme Assays / Q000379:methods*; D065089:Glycoside Hydrolase Inhibitors / Q000494:pharmacology*; D006046:Gold / Q000737:chemistry*; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D000520:alpha-Glucosidases / Q000378:metabolism*
D065089:Glycoside Hydrolase Inhibitors; D006046:Gold; D000520:alpha-Glucosidases
Colorimetric biosensor; Gold nanoparticle; Inhibitor; α-Glucosidase