Self-referenced detection of Cu2+ using a crossbar array of protein-stabilized gold nanocluster and a thermoplastic

Junfei Xiaa, Zhibin Wanga, Danting Huanga, Peipei Zhanga, Brett Kirklanda, Jingjiao Guana,b,*

aDepartment of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Florida State

University, Tallahassee, Florida, 32310, USA

bIntegrative NanoScience Institute, Florida State University, Tallahassee, Florida 32306, USA

Abstract

A simple strategy has been developed to construct a micrometer-sized self-referenced fluorescence sensor for detecting Cu2+. The method relies on microcontact printing of bovine serum albumin-stabilized gold nanocluster (BSA-AuNC) and poly(propyl methacrylate) (PPMA) stripes on a glass slide. The PPMA stripes are printed on the BSA-AuNC stripes to form a crossbar array, with its cell unit being composed of four distinct regions: BSA-AuNC, plain glass, PPMA, and BSA-AuNC covered by PPMA. The BSA-AuNC region is fluorescent and its fluorescence intensity is changeable upon contacting with analyte solution. The BSA-AuNC covered by PPMA is also fluorescent but insensitive to the analyte solution due to the presence of PPMA which prevents the analyte solution from contacting the BSA-AuNC. This region can thus be used as an internal reference for sensing. This self-referenced sensor is able to detect Cu2+ in a highly specific and concentration-dependent manner.
This micrometer-sized sensor allows sensitive, selective and self-referenced detection of Cu2+, and can potentially be integrated into lab-on-a-chip and microarray-based sensors. Moreover, this microcontact printing based fabrication approach is simple, inexpensive, and extendable to other sensory materials such as small-molecule fluorophores and nanocrystals quantum dots for various sensing application.