Adhesion layer-free attachment of gold on silicon wafer and its application in localized surface plasmon resonance-based biosensing.

The use of a metallic adhesion layer between plasmonic-active nanostructures and a solid supported is known to dampen the plasmonic response. To overcome this problem, organic adhesion layers have been introduced, which in turn can undermine the stability of the film. Moreover, both types of layers limit the regeneration of the nanostructures for multiple uses. Here we report a quick and simple approach to prepare intermediate adhesion layer-free binding of nanostructured films of gold on silicon wafers. The approach involves scratching and etching of the silicon wafer before sputter coating with a thin layer of Au. The plasmonic-active nanostructures were then prepared on this thin Au film using electrochemical deposition. As-prepared plasmonic-active nanostructured thin films of gold (PANTF-Au) are easy to handle, physically robust, and can be regenerated. The bulk refractive index sensitivity of PANTF-Au is 150 nm/RIU with the figure of merit 1.4, and with a plasmonic field-decay length of 27 nm. We further used these thin films to study interactions between lectin and glycoprotein inside a flow cell as well as on a microplate made of PANTF-Au. The PANTF-Au can be easily integrated with electrochemical devices and microfluidics, which can help to pave the way toward the development of ideal optical-electrochemical point-of-care biosensors.

Hybrid Mesoporous Silica Nanoparticles Grafted with 2-(tert-butylamino)ethyl Methacrylate-b-poly(ethylene Glycol) Methyl Ether Methacrylate Diblock Brushes as Drug Nanocarrier.

This paper introduces the synthesis of well-defined 2-(tert-butylamino)ethyl methacrylate-b-poly(ethylene glycol) methyl ether methacrylate diblock copolymer, which has been grafted onto mesoporous silica nanoparticles (PTBAEMA-b-PEGMEMA-MSNs) via atom transfer radical polymerization (ATRP). The ATRP initiators were first attached to the MSN surfaces, followed by the ATRP of 2-(tert-butylamino)ethyl methacrylate (PTBAEMA). CuBr2/bipy and ascorbic acid were employed as the catalyst and reducing agent, respectively, to grow a second polymer, poly(ethylene glycol) methyl ether methacrylate (PEGMEMA). The surface structures of these fabricated nanomaterials were then analyzed using Fourier Transform Infrared (FTIR) spectroscopy. The results of Thermogravimetric Analysis (TGA) show that ATRP could provide a high surface grafting density for polymers. Dynamic Light Scattering (DLS) was conducted to investigate the pH-responsive behavior of the diblock copolymer chains on the nanoparticle surface. In addition, multifunctional pH-sensitive PTBAEMA-b-PEGMEMA-MSNs were loaded with doxycycline (Doxy) to study their capacities and long-circulation time.