Au-Se bonded nanoprobe for prostate specific antigen detection in serum.

The detection of prostate specific antigen (PSA) in serum can realize early diagnosis of prostate cancer and prevent the occurrence of prostate tumors, as well as offering guidance during the therapy. Herein, a Au-Se bonded nanoprobes that can specifically detect PSA was designed and constructed. The peptide chains that can be specifically cleaved by PSA were firstly functionalized with fluorescent dye and selenol, and then bind to the Au nanoparticles to produce the probe. The dye's fluorescence was quenched due to the FRET effect, but recovered by PSA's cutting. The nanoprobe can detect PSA in serum with extraordinary anti-interference ability against other proteins (detection range 1-40 ng/mL). This work provides a new method for the detection of PSA in serum, and has potential guiding significance for clinical PSA detection.

Se-modified gold nanorods for enhancing the efficiency of photothermal therapy: avoiding the off-target problem induced by biothiols.

Tumor-targeting gold nanorods (AuNRs) assembled through Au-S bonds have been widely used for photothermal therapy (PTT) via intravenous injection. However, with extended in vivo circulation times, biothiols can replace some S-modified targeting ligands on the surface of the AuNRs, which lowers their targeting efficacy towards cancer cells, resulting in a non-ideal PTT effect. To address this problem, herein, we utilized Se-modified AuNRs to establish a dual functional nanoprobe (Casp-RGD-Se-AuNRs) for improving the therapeutic effect and real-time monitoring of Caspase-9 levels to indicate the degree of cell apoptosis. The experiments demonstrated that the Casp-RGD-Se-AuNRs are better at avoiding interference from biothiols than the S-modified nanoprobe (Casp-RGD-S-AuNRs) for extended blood-circulation times after intravenous injection, significantly improving the PTT efficacy via more effectively targeting cancer cells. Simultaneously, the change of Caspase-9 levels visually shows the degree of apoptosis. Moreover, an in vivo study showed that, compared with the S-modified nanoprobe, the Se-modified nanoprobe exhibits a higher delivery efficiency to the tumor region after intravenous injection (accumulation in the tumor increased by 87%) and a better anticancer efficacy under NIR light irradiation (the tumor inhibition rate increased 6-fold). This work provides a valuable strategy to overcome the off-target problem, and new ideas for avoiding interference by biomolecules during blood circulation.