Human serum albumin (HSA) is multifunctional protein, known to be a natural carrier for a number of endogenous and exogenous compounds, including drugs. Formulating anticancer drugs with HSA is a clinically validated approach to improve the pharmacological properties and provide targeted delivery (passive and active) of cytotoxic payload to the tumor (such as in Abraxane). A number of receptors facilitating HSA uptake from systemic circulation have been characterized. What is interesting, such uptake may differ depending on the nature and quantity of ligands bound to HSA. Based on this, one might like to modify the HSA in a way that its distribution is more favorable for certain therapeutic purposes, thus ensuring more efficient delivery of the therapeutic cargo to disease site. E.g. Levofloxacin (LV), broad spectrum antibiotic drug, could benefit from extended systemic exposure, and stronger interaction with plasma proteins could be useful for this purpose. We have engrafted monomeric or polymeric CDs on the surface of HSA molecules to strengthen the LV adsorption (CD-LV dissociation constant is three orders of magnitude lower than that for HSA-LF). We have found that (HSA-HPolS)conj+LV exhibited the highest activity against E. coli, whereas (HSA-HPCD)conj+LV was the most effective against B. subtilis; and both HSA conjugates were more potent than LV alone or LV with HSA. Further fine-tuning of HSA could yield an improvement in biodistribution, and thus a more favorable risk/benefit ratio.

Modern medical needs call for the efficient remedies against bacterial diseases including severe pulmonary infections reported as a secondary SARS-Cov-2 infection. Here, we propose imprinted drug ciprofloxacin (CF) into the polymer based on methyl-β-cyclodextrin (MCD) via template synthesis. The obtained polycarbamide nanoparticles possess CF's sustained drug release. The interaction of human serum albumin (HSA) with CF and CF-MCD carriers was conducted by FRET, FTIR, fluorescence, and circular dichroism spectroscopy. These studies uncovered that MCD decreases CF's binding efficiency by 2 times, whereas CF’s encapsulation in polymer matrix doubles the Ka value. The changes in HSA’s secondary structure indicate no alterations in the main mechanism of complex formation between CF and HSA in the presence of MCD-based carries. The drug delivery system demonstrates prolonged CF release at pH 7.4 in presence of HSA (model conditions of blood plasma). CF-MCD carriers inhibit E. coli and B. subtilis growth, but for MAX systems we observed a MIC’s increase (~2 times). We believe that our findings are important for further development of new efficient drug forms.