▎ 摘　　要

The abuse of tetracycline(TC) antibiotics causes the accumulationof their residue in the environment, which has an irreversible impacton food safety and human health. In light of this, it is vital tooffer a portable, quick, efficient, and selective sensing platformto detect TC instantly. Herein, we have successfully developed a sensorusing silk fibroin-decorated thiol-branched graphene oxide quantumdots through a well-known thiol-ene click reaction. It is appliedto ratiometric fluorescence sensing of TC in real samples in the linearrange of 0-90 nM, with the detection limit of 49.69, 47.76,55.25, 47.90, and 45.78 nM for deionized water, chicken sample, fishsample, human blood serum, and honey sample, respectively. With thegradual addition of TC to the liquid media, the sensor develops asynergetic luminous effect in which the fluorescence intensity ofthe nanoprobe steadily declines at 413 nm, while the intensity ofa newly emerging peak increases at 528 nm, maintaining a ratio thatis dependent on the analyte concentration. The increase of luminescenceproperties in the liquid media is clearly visible by naked eyes inthe presence of 365 nm UV light. The result helps us in building afilter paper strip-based portable smart sensor using an electric circuitcomprising a 365 nm LED (light-emitting diode) powered by a mobilephone battery which is attached just below the rear camera of a smartphone.The camera of the smartphone captures the color changes that occurthroughout the sensing process and translates into readable RGB data.The dependency of color intensity with respect to the concentrationof TC was evaluated by deducing a calibration curve from where thelimit of detection was calculated and found to be 0.125 mu M.These kinds of gadgets are important for the possible real-time, on-the-spot,quick detection of analytes in situations where high-end approachesare not easily accessible.