Highly specific electrochemical sensor of tumor marker using multi-nanoparticle labeling based 3D origami paper analytical device

Abstract

and synthesis of a fluorescent off–on nanoprobe for MMP families (for an instance, collagenase IV, including MMP2, MMP4, and MMP9). The fabricated fluorescent nano-switch is the fluorescein isothiocyanate (FITC)-attached gold nanoparticle (GNP). The spacer inserted between FITC andGNP is a small peptide containing the core substrate sequence of MMPs and a free thiol group on the terminal cysteine. To ensure the desirable solubility, stability, and in vivo circulation of nano-switch, thiolated polyethylene glycol monomethyl ether (HS-mPEG2000) was also conjugated to the surface of GNP. The structure of the nano-switch was optimized through adjusting the molar ratio of GNP vs. p-FITC, investigating the effect on the addition of HS-mPEG2000, and evaluating fluorescence recovery efficiency of the nano-switch. Investigated using confocal laser fluorescence microscope technology, the cellular uptake result showed that with the help of GNPs, the nano-switch can bemore easily in taken byHepG2 cells (liver hepatocellular carcinoma) and lighten the greenfluorescence of FITC around GNPs inside cells. However, the green fluorescence was only found in the cell culture medium for the p-FITC group. Furthermore, tissue frozen section results demonstrated that (1) the nano-switch showed higher fluorescence intensity in tumor tissues; (2) the fluorescence recovery of the nano-switch was not only found in the margin but also in the center of tumor tissues; (3) the nano-switch exhibited lower distribution in normal tissues including heart, spleen, and lung; and (4) when comparing with p-FITC, the similar and higher accumulation of the nano-switch in liver and kidney, respectively, indicated its liver targeting and renal elimination characters.