Abstract
Developing ideal surface-enhanced Raman scattering (SERS) substrates is significant in biological detection. Compared with free non-aggregated noble metal nanoparticles, loading metal nanoparticles on a large matrix can achieve a higher SERS effect due to the existence of many “hot spots”. A novel SERS substrate with intense “hot spots” was prepared through reducing gold ions with silicon nanocrystal containing polymer microspheres. The substrate exhibits high SERS sensitivity with an enhancement factor of 5.4 × 107. By applying 4-mercaptopyridine as a Raman reporter, the developed SERS substrate can realize measurement of pH values. The intensity ratio of 1574 to 1607 cm−1 of 4-mercaptopyridine showed excellent pH sensitivity, which increased as the surrounding pH increased. With good stability and reliability, the pH sensor is promising in the design of biological detection devices.
Highlights
Surface-enhanced Raman scattering has been continuously investigated in chemical and biological detection [1,2,3,4]
In order to obtain high scale silicon-derived particles, we reported a one-step approach to synthesize fluorescent silicon nanocrystal containing polymer microspheres (SiPS) by controlling the reaction between aminosilane and L-ascorbic acid [18]
The morphology of polystyrene microspheres (PS), PS/SiP, and hollow SiP microspheres (SiPM) was verified by SEM and TEM
Summary
Surface-enhanced Raman scattering has been continuously investigated in chemical and biological detection [1,2,3,4]. Parts of noble metal nanoparticles are embedded in the core part of silica, which cannot capture target molecules effectively compared with those on the surfaces. The preparation of highly sensitive SERS substrates remains a challenge Among these materials, silicon-based materials have attracted interest because of low-loss optical resonances in the visible region, well-controlled structure, and reducibility to noble metal ions. 4-MPy is the most frequently applied molecule, due to its sensitive pH response, high Raman signal, and strong affinity with the metal nanoparticles. The new SERS substrate, composed of gold nanoparticle stabilized silicon nanocrystal containing polymer microspheres, was successfully prepared. In order to obtain SERS-active materials, silicon nanocrystal embedded hollow microspheres were mixed with noble metal ions. To investigate the performance of the composites in pH measurement, 4-MPy was applied as a Raman-active molecule
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