Mesoporous Nanostructures Encapsulated with Metallic Nanodots for Smart SERS Sensing

Abstract

In virtue of uniform mesopores and core–shell nanoarchitectures, metallic nanodot-encapsulated hollow mesoporous nanostructures have shown promising potential in various applications. However, their fabrication with versatile tunability of the encapsulated metallic content has been a challenge. Herein, we have prepared metallic nanodot-encapsulated hollow mesoporous silica nanoparticles (M-HMSNPs) with adjustable inner metallic components. The sacrificial template of polystyrene (PS) nanoparticles precoated with metals (Au/Ag/Pt) is fully wrapped with mesoporous silica (mSiO2). The metallic nanodots are formed during the template removal process by calcination. The type and content of the encapsulated nanodots can be readily and precisely controlled by the initially deposited metallic layers. We demonstrate the application of the gold (Au) nanodot-loaded HMSNPs (denoted Au-HMSNPs) as smart surface-enhanced Raman spectroscopy (SERS) probes, which can screen between big molecules and small analytes. With the aid of a Raman reporter, the SERS probe can successfully quantify H2O2, which is used to distinguish cancer cells in vitro. Further integrated with enzymes, the SERS chips of specificity are prepared and used to detect corresponding substrates of glucose and uric acid, responsively. Besides SERS sensing, the current strategy can inspire future development of many other M-HMSNPs for various applications such as catalysis, energy storage, theranostics, etc.

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“… 4 , 5 Currently, the SERS technique has been extensively applied in drug analysis, 6 virus detection, 7 , 8 food safety, 9 , 10 and biomedical sensors. 11 , 12 Usually, the efficiency of SERS signals is enormously derived from the geometric shape of metal nanostructures and their gap. Compared with the regular nanostructures (such as spheres), the shape can induce higher-density surface plasmons (SPs).…”

“…Surface-enhanced Raman scattering (SERS), a great enhancement effect of the local electromagnetic field caused by the collective oscillation of electrons in a conductive nanostructure (called the local surface plasmon resonance (LSPR)), − has been proven to be an ultrasensitive technique to obtain highly specific Raman signals of targeting trace molecules. , Currently, the SERS technique has been extensively applied in drug analysis, virus detection, , food safety, , and biomedical sensors. , Usually, the efficiency of SERS signals is enormously derived from the geometric shape of metal nanostructures and their gap. Compared with the regular nanostructures (such as spheres), the shape can induce higher-density surface plasmons (SPs).…”