Macro-, Micro- and Nano-Roughness of Carbon-Based Interface with the Living Cells: Towards a Versatile Bio-Sensing Platform

Diamond nanoneedles for biosensing

Nanoparticles and nanomaterials are revolutionizing medicine by offering diverse tools for diagnosis and therapy, including devices, contrast agents, drug delivery systems, adjuvants, therapeutics, and theragnostic agents. Realizing full applied potential requires a deep understanding of the interactions of nano dimensional objects with biological cells. In this study, we investigate interaction of single-crystal diamond nanoneedles (SCDNNs) containing silicon vacancy (SiV-) color centers with biological substances. Four batches of the diamond needles with sizes ranging between 200 nm and 1300 nm and their water suspensions were used in these studies. The human lung fibroblast cells were used for the proof-of-concept demonstration. Employing micro-photoluminescence (PL) mapping, confocal microscopy, and lactate dehydrogenase (LDH) viability tests, we evaluated the cellular response to the SCDNNs. Intriguingly, our investigation with PL spectroscopy revealed that the cells and SCDNNs can coexist together with approved efficient registration of SiV-centers presence. Notably, LDH release remained minimal in cells exposed to optimally sized SCDNNs, suggesting a small number of lysed cells, and indicating non-cytotoxicity in concentrations of 2-32µg ml-1. The evidence obtained highlights the potential of SCDNNs for extra- or/and intracellular drug delivery when the surface of the needle is modified. In addition, fluorescent defects in the SCDNNs can be used for bioimaging as well as optical and quantum sensing.

Black Silicon Surface-Enhanced Raman Spectroscopy Biosensors: Current Advances and Prospects

Black silicon was discovered by accident and considered an undesirable by-product of the silicon industry. A highly modified surface, consisting of pyramids, needles, holes, pillars, etc., provides high light absorption from the UV to the NIR range and gives black silicon its color-matte black. Although black silicon has already attracted some interest as a promising material for sensitive sensors, the potential of this material has not yet been fully exploited. Over the past three decades, black silicon has been actively introduced as a substrate for surface-enhanced Raman spectroscopy (SERS)-a molecule-specific vibrational spectroscopy technique-and successful proof-of-concept experiments have been conducted. This review focuses on the current progress in black silicon SERS biosensor fabrication, the recent advances in the design of the surface morphology and an analysis of the relation of surface micro-structuring and SERS efficiency and sensitivity. Much attention is paid to problems of non-invasiveness of the technique and biocompatibility of black silicon, its advantages over other SERS biosensors, cost-effectiveness and reproducibility, as well as the expansion of black silicon applications. The question of existing limitations and ways to overcome them is also addressed.

From Basic Science to Clinical Perfection: What Defines the Orthopedic Biocompatible Implant?

The general improvement in life expectancy and standard of living makes it easier for patients to get access to routine medical exams and is anticipated to increase the prevalence of several degenerative joint illnesses. In addition, it is anticipated that their incidence will increase both nationally and internationally, which will raise the demand for novel and long-lasting implantable devices in the field of orthopedics. The current review’s goals are to define what constitutes a biocompatible orthopedic implant in terms of in vitro biocompatibility testing and to clarify important concepts and definitions that are already in use. The demand for materials and implants made of various tissues is now increasing, and the ongoing advancement of in vitro cell culture studies is a reliable practical tool for examining the biocompatibility of potential implantable materials. In vitro biocompatibility research has been reduced and, in most cases, diminished to laboratory studies that no longer or drastically reduce animal sacrifice as a response to the well-known three “Rs” (“reduction”, “refinement”, and “replacement”) introduced to literature by English academics in the 1960s. As technology advances at an astounding rate, a new generation of gene-activating biomaterials tailored for specific people and disease conditions might emerge in the near future.

Surface-Enhanced Raman Spectroscopy of Organic Molecules and Living Cells with Gold-Plated Black Silicon

Black silicon (bSi) refers to an etched silicon surface comprising arrays of microcones that effectively suppress reflection from UV to near-infrared (NIR) while simultaneously enhancing the scattering and absorption of light. This makes bSi covered with a nm-thin layer of plasmonic metal, i.e., gold, an attractive substrate material for sensing of bio-macromolecules and living cells using surface-enhanced Raman spectroscopy (SERS). The performed Raman measurements accompanied with finite element numerical simulation and density functional theory analysis revealed that at the 785 nm excitation wavelength, the SERS enhancement factor of the bSi/Au substrate is as high as 10⁸ due to a combination of electromagnetic and chemical mechanisms. This finding makes the SERS-active bSi/Au substrate suitable for detecting trace amounts of organic molecules. We demonstrate the outstanding performance of this substrate by highly sensitive and specific detection of a small organic molecule of 4-mercaptobenzoic acid and living C6 rat glioma cell nucleic acids/proteins/lipids. Specifically, the bSi/Au SERS-active substrate offers a unique opportunity to investigate the living cells' malignant transformation using characteristic protein disulfide Raman bands as a marker. Our findings evidence that bSi/Au provides a pathway to the highly sensitive and selective, scalable, and low-cost substrate for lab-on-a-chip SERS biosensors that can be integrated into silicon-based photonics devices.