In medical research the visualization of drug carrier accumulation and release of the loaded drugs in vivo is an important field. In this work, two protein-stabilized gold nanoclusters (Au NCs) as effective fluorescent reporters (FRs) were investigated for labeling of biocompatible chitosan-modified hyaluronic acid based nanocarriers having two different structures. The colloid stability of the labeled carriers was studied by dynamic light scattering and Zeta potential measurements, while the changes in the fluorescence of the lysozyme- (LYZ) and bovine serum albumin (BSA)-stabilized Au NCs were analyzed by spectrofluorimetry and confocal fluorescent microscopy. We found that the labeling was effective with a wide range of marker:carrier mass ratios, and the fluorescence of the NCs and the colloid stability of the complexes were retained. Labeling during preparation and subsequent labeling were compared, and based on composition (nanocluster:carrier mass ratio) and structure of the complex systems we preferred the latter method, as it left the Au NCs free for further modifications. Considering both marker:carrier mass ratios and emission intensities, the LYZ-stabilized Au NCs proved to be better labels. The core-shell type carrier formulations showed increased fluorescence with LYZ-stabilized NCs, presumably from aggregation induced emission.

In this work, we developed multifunctional hydrogel nanoparticles (NPs) that can encapsulate anticancer drugs and imaging contrast agents as well. Mitomycin C (MMC) and rhodamine B (RB) were selected as models for anticancer drugs and imaging contrasting agents, respectively. Both MMC and RB were linked to the succinated polyvinyl alcohol polymer (PVA-SA). The selected labeled hydrogel NPs ((0.5% RB)-PVA-SA NPs and (1.5% RB)-PVA-SA NPs) improved the RB quantum yield from 29.8% to a minimum of 42.7%. Moreover, they showed higher emission stability compared to free RB when they were repeatedly excited at 554 nm for 2 h. Furthermore, the dye polymeric interactions significantly increased the RB fluorescence lifetime by approximately twofold. All these optical properties pave the way for our labeled hydrogel NPs to be used in imaging-guided therapy. For the labeled MMC-loaded NPs, the MMC-binding efficiency was found to be exceedingly high in all synthesized samples: a minimum of 92% was achieved. In addition, the obtained pH-dependent drug release profiles as well as the cytotoxicity evaluation demonstrated the high potential of releasing MMC under acidic cancerous conditions. Moreover, the in vitro cellular uptake experiment confirmed the accumulation of MMC NPs throughout the cytoplasm.

The rational design of mixed micellar systems has emerged as a cornerstone of modern nanomedicine, offering unprecedented control over the solubility and bioavailability of challenging therapeutic agents. This review provides a comprehensive analysis of the physicochemical principles governing the assembly of amphiphilic drugs and surfactants into synergistic nanostructures. By articulating the transition from traditional guest/host solubilization to “drug-as-component” models, we highlight the critical role of molecular interactions in achieving therapeutic precision. It further outlines the experimental methodologies used to investigate these systems and elucidates how they enhance the solubility, stability, and bioavailability of poorly water-soluble drugs. Special emphasis is placed on the practical applications of synergy in reducing systemic toxicity and optimizing drug release kinetics, providing a roadmap for the development of next-generation nano-pharmaceuticals. The functionality of these systems is significantly influenced by the molecular interactions among their constituents; thus, quantitative analysis of these interactions might enhance the formulation of more effective pharmaceuticals. This review outlines the key physicochemical principles of mixed micelle formation, including thermodynamics and synergistic interactions of amphiphiles, while emphasizing their relevance in current research and practical pharmaceutical applications. Various experimental methods, such as surface tension measurement, conductometric and calorimetric tests, and spectroscopic techniques, are compared in terms of their conditions of application and performance in understanding micelle formation and micelle structure. We clearly point out that the interpretation and evaluation of the properties of colloidal systems containing drug molecules solubilized by mixed micelles and an amphiphilic drug incorporated into micelles must be discussed and evaluated separately. Understanding the limitations and characteristics of the physical/chemical principles applied is essential for the rational design of mixed micelle carriers tailored to specific therapeutic needs.

Bimetallic nanoclusters (NCs) containing gold and silver were prepared by template-assisted synthesis using human serum albumin (HSA) via a newly optimized fabrication route at 25 °C. Additionally, following this procedure, we also reproducibly synthesized further Au/Ag NCs, containing a similar Au:Ag ratio, using bovine serum albumin (BSA), lysozyme (LYZ), transferrin (Tf), and gamma-globulin (γG). The aim was to highlight the importance of experimental conditions of the synthesis (e.g., metal ion: protein molar ratio and metal and protein concentrations, as well as synthesis time, temperature, and pH) for the composition, structure, and optical features of the protein-stabilized ultra-small-sized products. Circular dichroism (CD) spectroscopy revealed that the partial unfolding of the stabilizing proteins is primarily caused by the alkaline synthesis environment rather than the nanocluster formation itself. Furthermore, X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometry (ICP-MS) successfully confirmed the presence of mainly metallic (Au⁰) core structures alongside Ag⁰/Ag⁺ species, providing the actual metal-to-protein ratios after purification. As a new result, cytotoxicity of these bimetallic NCs was determined by using doxorubicin-sensitive Colo205 and CCD-19Lu human normal fibroblast cell lines, and their antibacterial activity was also evaluated using four different Gram-positive and Gram-negative bacterial strains.

The photocatalytic activity of semiconductors can be tuned by changing their morphological or structural properties. However, a simpler and direct method is the introduction of a cocatalyst, for example V₂O₅ or V₂O₅/V₄O₉. In the present work, this was the cocatalyst added to SrTiO₃. The deposition method was directed in such a way that the cocatalyst did not cover the surface of the SrTiO₃ completely. This way, the photocatalytic process (phenol conversion) takes place at the surface of the main catalyst, while the lifetime of the generated charge carriers is increased through electron trapping via the presence of vanadium oxides. The V₂O₅/V₄O₉ cocatalyst influences the recombination processes of excited electrons in SrTiO₃ by modifying the near-surface defects of SrTiO₃, and it can efficiently capture electrons due to the formed heterojunction. The V₄O₉ content enables efficient electron transfer, as its structure can accommodate V⁴⁺ in addition to V⁵⁺. Therefore, a mixed-phase semiconductor is more suitable as a cocatalyst than a single-phase semiconductor. In this work, the photocatalytic activity of SrTiO₃ was investigated in the presence of V₂O₅ (0–20 wt.%). It was found that all the samples that contained the cocatalyst showed higher photocatalytic activity than the unmodified SrTiO₃. The sample containing 10 wt.% of cocatalyst performed ~5.4 times better than pristine SrTiO₃ (35.87 µmol_phenol/g_catalyst, vs. 7.74 µmol_phenol/g_catalyst). This sample also contains a relatively high amount of V₄O₉ compared to the other samples, in addition to V₂O₅, which may be the main reason for the enhanced photocatalytic performance.