Chemical imaging of live fibroblasts by SERS effective nanofilm.

Reliable and strong surface enhanced Raman scattering (SERS) signatures of intracellular compartments in live NIH3T3 fibroblasts are collected in real time by means of SERS active thin nanofilm (30 nm) on colloidal silica (1.5 µm). Nanofilm is composed of preformed silver nanoparticles in the matrix of polyacrylic acid, protecting against heating (37 °C) in water, or culture medium or phosphate buffered saline aqueous solution. The SERS enhancement factors (EFs) of the order 10(8) allow single biomolecule detection in the native environment of a single live cell. Primary and secondary SERS hot spots of nanofilm are responsible for such high EFs. A slow SERS EF intensity decay occurs over a broader distance of micron silica with nanofilm, not achievable in a common core-shell model (silver nanoparticle coated with a thin silica layer). Extensive local field EFs and SERS EFs are mainly delivered by prolate silver nanoparticles ("rugby-like" shape). This is achieved if an incident field is polarized along the z-axis and the direction of incident polarization and main axis (z) are perpendicular to each other, not observable in water or on gold.

Bioinspired nanovalves with selective permeability and pH sensitivity.

Biological systems with controlled permeability and release functionality, which are among the successful examples of living beings to survive in evolution, have attracted intensive investigation and have been mimicked due to their broad spectrum of applications. We present in this work, for the first time, an example of nuclear pore complexes (NPCs)-inspired controlled release system that exhibits on-demand release of angstrom-sized molecules. We do so in a cost-effective way by stabilizing porous cobalt basic carbonates as nanovalves and realizing pH-sensitive release of entrapped subnano cargo. The proof-of-concept work also consists of the establishment of two mathematical models to explain the selective permeability of the nanovalves. Finally, gram-sized (or larger) quantities of the bio-inspired controlled release system can be synthesized through a scaling-up strategy, which opens up opportunities for controlled release of functional molecules in wider practical applications.

Single-crystalline ZnO spherical particles by pulsed laser irradiation of colloidal nanoparticles for ultraviolet photodetection.

We report the formation and ultraviolet (UV) photodetection of single-crystalline spherical ZnO particles by pulsed laser irradiation of commercial ZnO nanoparticles in water. The phase and microstructure analysis before and after laser irradiation reveals a crystal size increase and shape transformation from irregular to spherical. Time-dependent laser irradiation confirmed that fusion is the reason for nanoparticle growth up to single-crystalline spherical particles. After rapid cooling, they maintain size and shape and possess unique optical and electrical properties. Because of the single-crystalline feature and smooth surfaces, high and selective sensing of ultraviolet light is observed.