In order to detect the redox states of fruits and vegetables simply, a SERS (surface-enhanced Raman scattering) method was developed based on a redox-sensitive probe and a pH-sensitive probe. The two probes were dropped onto the flesh of the fresh incision of fruits and vegetables, respectively. The SERS spectra of redox-sensitive probes were used to indicate their redox states, and the SERS spectra of pH-sensitive probes were used to indicate their pH values to discount the influence of pH on the redox states. The order of redox states (redox potential) of the detected fruits and vegetables is as follows: carrot < Green delicious apple < Xinjiang kuerle fragrant pear < Chinese royal pear < Fuji apple < crystal pear < Golden marshall apple < potato. Compared with traditional methods based on the detection of extracts, the developed method is simple without any pretreatments and consumption of additional chemicals, which would become a popular evaluation methodology of the redox states of fruits and vegetables during their growth and storage stages.

The developed method for monitoring GST, an important drug metabolic enzyme, could greatly facilitate researches on relative biological fields. In this work, we have developed a SERS technique to monitor the absorbance behaviour of 6-mercaptopurine (6-MP) and its glutathione-S-transferase (GST)-accelerated glutathione (GSH)-triggered release behaviour on the surface of gold nanoflowers (GNFs), using the GNFs as excellent SERS substrates. The SERS signal was used as an indicator of absorbance or release of 6-MP on the gold surface. We found that GST can accelerate GSH-triggered release behaviour of 6-MP from the gold surface. We speculated that GST catalyzes nucleophilic GSH to competitively bind with the electrophilic substance 6-MP. Experimental results have proved that the presented SERS protocol can be utilized as an effective tool for accessing the release of anticancer drugs.

For the sensitive and convenient detection of acute liver injury, several methods and materials have been developed. However, it is still a challenge to obtain sensitive, simple detection techniques for acute liver injury. Here, based on a gold nanoflowers (GNFs) modified substrate and 6-mercaptopurine (6-MP) as a surface-enhanced Raman scattering (SERS) signal molecule, a novel method was developed for monitoring carbon tetrachloride (CCl 4 )-induced acute liver injury of mice. Glutathione (GSH)-triggered and glutathione-s-transferase (GST)-accelerated the turn-off SERS behavior of 6-MP was studied on the GNFs substrate. We found that GSH-triggered GST-accelerated turn-off behavior of 6-MP on the GNFs substrate surface in buffer systems. In CCl 4 -induced acute liver injury mice tissue extracts without adding GST, the turn-off behavior of 6-MP was also accelerated, the detection intensity from 10 5 down to 10 3 counts for 6-MP. The SERS results confirmed that GNFs substrate exhibited strong SERS signal intensity, excellent stability in complex biological environment and detection clinical sample. This study provides a new, rapid and sensitive approach for analysis of trace amounts detection based on SERS coupled with GNFs substrate, which has great potential for analysis of surface chemical properties indicating its potential applicability in biological and biomedical research.