Glucose-responsive multifunctional acupuncture needle: A universal SERS detection strategy of small biomolecules in vivo

Abstract

To detect glucose in vivo with minimal invasion, a glucose-responsive multifunctional acupuncture needle was developed by integrating glucose oxidase (GOx, signal convertor), 4-mercaptobenzoic acid (4-MBA, signal reporter), and a microporous polystyrene (PS)-coated SERS-active acupuncture needle (signal amplifier) which was also used as an integration carrier and sampling device. On the needle, the integrated GOx converted glucose to gluconic acid which changed pH value of the microenvironment and then, the integrated 4-MBA reported the changed pH which indirectly reported the glucose concentration. The integrated SERS-active materials enhanced Raman signal of 4-MBA to provide an optical readout of the glucose concentration. The SERS detection did not depend on the affinity to SERS substrates and intrinsic Raman activity of glucose. Integrating suitable enzymes and corresponding reporters on microporous PS-coated SERS-active needles, the method can become a universal strategy to SERS detection of small biomolecules in vivo.