Monitoring of tiny intracell temperature variations is of high importance to understand the mechanisms of exothermic/endothermic processes inside the living cells. Small shifts in thermal balance may drastically influence cell functioning and induce pathological conditions. By using biocompatible diamond single‐crystal microneedles enriched with nitrogen‐vacancy (NV)/silicon‐vacancy (SiV) color centers, this study demonstrates all‐optical in vitro temperature monitoring in the physiologically significant range (25–55 °C). Zero‐phonon line (ZPL) of SiV centers belonging to the “therapeutic window” is used to improve measurement precision via suppression of the tissue autofluorescence. The simultaneous detection of the NV and SiV fluorescence enables two‐band visualization of the living cells combined with the temperature sensing. This study demonstrates experimentally that temperature can be measured by lifetime, full‐width at half maximum, and peak position of SiV ZPL, while accuracy can be further improved by normalizing the photoluminescence (PL) ZPL peak intensity on the PL signal measured at the wavelength where it is temperature independent. According to performed numerical simulations diamond microneedles enable real‐time temperature measurements because their characteristic heating time is less than 10 ns. The results open a way toward accurate, noninvasive, precise, and real‐time monitoring of temperature variations accompanying intracellular biochemical reactions and processes on the single‐cell level.

Black silicon (bSi) is a highly absorptive material in the UV-vis and NIR spectral range. Photon trapping ability makes noble metal plated bSi attractive for fabrication of surface enhanced Raman spectroscopy (SERS) substrates. By using a cost-effective room temperature reactive ion etching method, we designed and fabricated the bSi surface profile, which provides the maximum Raman signal enhancement under NIR excitation when a nanometrically-thin gold layer is deposited. The proposed bSi substrates are reliable, uniform, low cost and effective for SERS-based detection of analytes, making these materials essential for medicine, forensics and environmental monitoring. Numerical simulation revealed that painting bSi with a defected gold layer resulted in an increase in the plasmonic hot spots, and a substantial increase in the absorption cross-section in the NIR range.

A systematic spectroscopic characterization of highly homogeneous water suspensions of ‘buckydiamonds’ comprising sp3 cubic nanodiamond (ND) core covered with disordered sp2 shell densely decorated with oxygen-containing groups demonstrates the excitation-wavelength-dependent photoluminescence (PL) given by at least four types of specific structures on the ND surface (hydroxyl, C=O containing ketones, carboxylic anhydrides, and carboxyl groups). PL properties of NDs suspensions possess concentration-dependent behavior revealing tendency of NDs to agglomerate. PL of NDs has been found to be strongly sensitive to pH of the environment in wide range of pH values, i.e., 2-11. We disclosed the mechanisms of pH sensitivity of the ‘buckydiamond’ and proved that it can serve as all-optical sensor of tiny pH variations suitable for further exploitation for pH sensing locally in the area where NDs have been delivered for any purpose, e.g., bioimaging or therapeutic needs.

The electromagnetic properties of chloroprene rubber after long-term ultraviolet ageing, oil immersion and thermal degradation were experimentally investigated in the frequency range from 1 kHz up to 1 THz. Ageing was shown in terms of mechanical degradation and the change in the complex dielectric permittivity. Within the whole investigated frequency range decrease of dielectric permittivity was observed after thermal treatment combined with oil immersion in comparison with chloroprene rubber stored under normal conditions. In contrast, thermal and ultraviolet ageing without immersion leads to increase of rubbers dielectric permittivity in all investigated frequency ranges. A non-invasive express method of degradation detection is proposed and proofed.

We propose a simple, fast, and low-cost method for producing Aucoated black Si-based SERS-active substrates with a proven enhancement factor of 10 6 . Room temperature reactive ion etching of silicon wafer followed by nanometer-thin gold sputtering allows the formation of a highly developed lacetype Si surface covered with homogeneously distributed gold islands. The mosaic structure of deposited gold allows the use of Au-uncovered Si domains for Raman peak intensity normalization. The fabricated SERS substrates have prominent uniformity (with less than 6% SERS signal variations over large areas, 100 × 100 μm 2 ). It has been found that the storage of SERS-active substrates in an ambient environment reduces the SERS signal by less than 3% in 1 month and not more than 40% in 20 months. We showed that Au-coated black Si-based SERS-active substrates can be reused after oxygen plasma cleaning and developed relevant protocols for removing covalently bonded and electrostatically attached molecules. Experiments revealed that the Raman signal of 4-MBA molecules covalently bonded to the Au coating measured after the 10th cycle was just 4 times lower than that observed for the virgin substrate. A case study of the reusability of the black Si-based substrate was conducted for the subsequent detection of 10 −5 M doxorubicin, a widely used anticancer drug, after the reuse cycle. The obtained SERS spectra of doxorubicin were highly reproducible. We demonstrated that the fabricated substrate permits not only qualitative but also quantitative monitoring of analytes and is suitable for the determination of concentrations of doxorubicin in the range of 10 −9 −10 −4 M. Reusable, stable, reliable, durable, low-cost Au-coated black Si-based SERS-active substrates are promising tools for routine laboratory research in different areas of science and healthcare.