Polyelectrolyte microcapsules and other targeted drug delivery systems could substantially reduce the side effects of drug and overall toxicity. At the same time, the cardiovascular system is a unique transport avenue that can deliver drug carriers to any tissue and organ. However, one of the most important potential problems of drug carrier systemic administration in clinical practice is that the carriers might cause circulatory disorders, the development of pulmonary embolism, ischemia, and tissue necrosis due to the blockage of small capillaries. Thus, the presented work aims to find out the processes occurring in the bloodstream after the systemic injection of polyelectrolyte capsules that are 5 μm in size. It was shown that 1 min after injection, the number of circulating capsules decreases several times, and after 15 min less than 1% of the injected dose is registered in the blood. By this time, most capsules accumulate in the lungs, liver, and kidneys. However, magnetic field action could slightly increase the accumulation of capsules in the region-of-interest. For the first time, we have investigated the real-time blood flow changes in vital organs in vivo after intravenous injection of microcapsules using a laser speckle contrast imaging system. We have demonstrated that the organism can adapt to the emergence of drug carriers in the blood and their accumulation in the vessels of vital organs. Additionally, we have evaluated the safety of the intravenous administration of various doses of microcapsules.

Flow cytometry nowadays is among the main working instruments in modern biology paving the way for clinics to provide early, quick, and reliable diagnostics of many blood-related diseases. The major problem for clinical applications is the detection of rare pathogenic objects in patient blood. These objects can be circulating tumor cells, very rare during the early stages of cancer development, various microorganisms and parasites in the blood during acute blood infections. All of these rare diagnostic objects can be detected and identified very rapidly to save a patient’s life. This review outlines the main techniques of visualization of rare objects in the blood flow, methods for extraction of such objects from the blood flow for further investigations and new approaches to identify the objects automatically with the modern deep learning methods.

Layer-by-layer assembled polymeric multilayer capsules (PMC) of micrometer sizes are permeable for molecules below 1 KDa; therefore, the efficacy of such capsules in the delivery of low molecular weight water soluble bioactive compounds and drugs is frequently challenged. Thermally induced contraction of hollow PMC is explored here to enhance their loading efficacy with model compound, fluorescent rhodamine B (RhB). Four bilayered capsules obtained of poly(diallyldimethylammonium chloride)/polystyrene sulfonate ([PDADMAC/PSS] ) or poly-l-arginine/dextran sulfate ([PARG/DS] ) on sacrificial CaCO spherical microparticles are postloaded with RhB at ambient or elevated temperatures. The influence of heat on capsule loading is determined quantitatively by varying the amounts of capsules in the batch and keeping the concentration of RhB constant. The applied heat improves the loading efficacy of [PDADMAC/PSS] capsules at concentrations up to 2.25 × 10 capsules mL , but has a reversed effect on [PARG/DS] capsules at all studied concentrations ((0-3.5) × 10 capsules mL ).