Semiconductor nanocrystals known as quantum dots (QDs) are of great interest for researchers and have potential use in various applications in biomedicine, such as in vitro diagnostics, molecular tracking, in vivo imaging, and drug delivery. Systematic analysis of potential hazardous effects of QDs is necessary to ensure their safe use. In this study, we obtained water-soluble core/shell QDs differing in size, surface charge, and chemical composition of the core. All the synthesized QDs were modified with polyethylene glycol derivatives to obtain outer organic shells protecting them from degradation. The physical and chemical parameters were fully characterized. In vitro cytotoxicity of the QDs was estimated in both normal and tumor cell lines. We demonstrated that QDs with the smallest size had the highest in vitro cytotoxicity. The most toxic QDs were characterized by a low negative surface charge, while positively charged QDs were less cytotoxic, and QDs with a greater negative charge were the least toxic. In contrast, the chemical composition of the QD core did not noticeably affect the cytotoxicity in vitro. This study provides a better understanding of the influence of the QD parameters on their cytotoxicity and can be used to improve the design of QDs.

Nano- and microparticles are increasingly widely used in biomedical research and applications, particularly as specific labels and targeted delivery vehicles. Silica has long been considered the best material for such vehicles, but it has some disadvantages limiting its potential, such as the proneness of silica-based carriers to spontaneous drug release. Calcium carbonate (CaCO₃) is an emerging alternative, being an easily available, cost-effective, and biocompatible material with high porosity and surface reactivity, which makes it an attractive choice for targeted drug delivery. CaCO₃ particles are used in this field in the form of either bare CaCO₃ microbeads or core/shell microparticles representing polymer-coated CaCO₃ cores. In addition, they serve as removable templates for obtaining hollow polymer microcapsules. Each of these types of particles has its specific advantages in terms of biomedical applications. CaCO₃ microbeads are primarily used due to their capacity for carrying pharmaceutics, whereas core/shell systems ensure better protection of the drug-loaded core from the environment. Hollow polymer capsules are particularly attractive because they can encapsulate large amounts of pharmaceutical agents and can be so designed as to release their contents in the target site in response to specific stimuli. This review focuses first on the chemistry of the CaCO₃ cores, core/shell microbeads, and polymer microcapsules. Then, systems using these structures for the delivery of therapeutic agents, including drugs, proteins, and DNA, are outlined. The results of the systematic analysis of available data are presented. They show that the encapsulation of various therapeutic agents in CaCO₃-based microbeads or polymer microcapsules is a promising technique of drug delivery, especially in cancer therapy, enhancing drug bioavailability and specific targeting of cancer cells while reducing side effects. To date, research in CaCO₃-based microparticles and polymer microcapsules assembled on CaCO₃ templates has mainly dealt with their properties in vitro, whereas their in vivo behavior still remains poorly studied. However, the enormous potential of these highly biocompatible carriers for in vivo applications is undoubted. This last issue is addressed in depth in the Conclusions and Outlook sections of the review.

Engineered nano- and microparticles are considered as promising tools in biomedical applications, such as imaging, sensing, and drug delivery. Protein adsorption on these particles in biological media is an important factor affecting their properties, cellular interactions, and biological fate. Understanding the parameters determining the efficiency and pattern of protein adsorption is crucial for the development of effective biocompatible particle-based applications. This review focuses on the influence of the morphological and physicochemical properties of particles on protein adsorption, including the pattern and amount of the adsorbed protein species, as well as the relative abundance of proteins with specific functions or physicochemical parameters. The effects of functionalization of the particle surface with polyethylene glycol, zwitterions, zwitterionic polymers, or proteins on the subsequent protein adsorption are analyzed. In addition, the dependences of protein adsorption on the protein species, biological buffers, fluids, tissues, and other experimental conditions are looked into. The influence of protein adsorption on the targeting efficiency of particle-based delivery systems is also discussed. Finally, the effect of the adsorbed protein corona on the interaction of the engineered micro- and nanoparticles with cells and the roles of specific proteins adsorbed on the particle surface in the recognition of the particles by the immune system are considered.

High-throughput protein assays are crucial for modern diagnostics, drug discovery, proteomics, and other fields of biology and medicine. It allows simultaneous detection of hundreds of analytes and miniaturization of both fabrication and analytical procedures. Photonic crystal surface mode (PC SM) imaging is an effective alternative to surface plasmon resonance (SPR) imaging used in conventional gold-coated, label-free biosensors. PC SM imaging is advantageous as a quick, label-free, and reproducible technique for multiplexed analysis of biomolecular interactions. PC SM sensors are characterized by a longer signal propagation at the cost of a lower spatial resolution, which makes them more sensitive than classical SPR imaging sensors. We describe an approach for designing label-free protein biosensing assays employing PC SM imaging in the microfluidic mode. Label-free, real-time detection of PC SM imaging biosensors using two-dimensional imaging of binding events has been designed to study arrays of model proteins (antibodies, immunoglobulin G-binding proteins, serum proteins, and DNA repair proteins) at 96 points prepared by automated spotting. The data prove feasibility of simultaneous PC SM imaging of multiple protein interactions. The results pave the way to further develop PC SM imaging as an advanced label-free microfluidic assay for the multiplexed detection of protein interactions.

Engineered nano- and microparticles are considered as promising tools in biomedical applications, such as imaging, sensing, and drug delivery. Protein adsorption on these particles in biological media is an important factor affecting their properties, cellular interactions, and biological fate. Understanding the parameters determining the efficiency and pattern of protein adsorption is crucial for the development of effective biocompatible particle-based applications. This review focuses on the influence of the morphological and physicochemical properties of particles on protein adsorption, including the pattern and amount of the adsorbed protein species, as well as the relative abundance of proteins with specific functions or physicochemical parameters. The effects of functionalization of the particle surface with polyethylene glycol, zwitterions, zwitterionic polymers, or proteins (precoating) on the subsequent protein adsorption are analyzed. In addition, the dependences of protein adsorption on the protein species, biological buffers, fluids, tissues, and other experimental conditions are considered. The influence of protein adsorption on the targeting efficiency of particle-based delivery systems is also discussed. Finally, the effect of the adsorbed protein corona on the interaction of the engineered micro- and nanoparticles with cells and the roles of specific proteins adsorbed on the particle surface in the recognition of the particles by the immune system are discussed.