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The isolation of small extracellular vesicles (sEVs), including those secreted by pathological cells, with high efficiency and purity is highly demanded for research studies and practical applications. Conventional sEV isolation methods suffer from low yield, presence of contaminants, long-term operation and high costs. Bead-assisted platforms are considered to be effective for trapping sEVs with high recovery yield and sufficient purity for further molecular profiling. In this study, magnetically responsive beads made of calcium carbonate (CaCO3) particles impregnated with iron oxide (Fe3O4) nanoparticles are fabricated using a freezing-induced loading (FIL) method. The developed magnetic beads demonstrate sufficient magnetization and can be collected by a permanent magnet, ensuring their rapid and gentle capture from an aqueous solution. The tannic acid on the surface of magnetic beads is formed by a layer-by-layer (LbL) method and is used to induce coupling of sEVs with the surface of magnetic beads. These tannic acid coated magnetic beads (TAMB) were applied to capture sEVs derived from MCF7 and HCT116 cell lines. Quantitative data derived from nanoparticle tracking analysis (NTA) and BCA methods revealed the capture efficiency and recovery yield of about 60%. High-resolution transmission electron microscopy (HRTEM) imaging of sEVs on the surface of TAMBs indicated their structural integrity. Compared with the size exclusion chromatography (SEC) method, the proposed approach demonstrated comparable efficiency in terms of recovery yield and purity, while offering a relatively short operation time. These results highlight the high potential of the TAMB approach for the enrichment of sEVs from biological fluids, such as cell culture media. [ABSTRACT FROM AUTHOR]

Coupling photosensitizers (PSs) with plasmonic nanoparticles increases the photocatalytic activity of PSs as the localized surface plasmon resonance (LSPR) of plasmonic nanoparticles leads to extreme concentration of light in their vicinity known as the near‐field enhancement effect. To realize this in a colloidal phase, efficient conjugation of the PS molecules with the plasmonic nanoparticle surface is critical. In this work, we demonstrate the coupling of phthalocyanine (Pc) molecules with gold nanoparticles (AuNPs) in the colloidal phase via click chemistry. This conjugated Pc‐AuNPs colloidal system is shown to enhance the photocatalytic singlet oxygen (1O2) production over non‐conjugated Pcs and hence improve the photoelectrochemical detection of phenols. The plasmonic enhancement of the 1O2 generation by Pcs was clearly elucidated by complementary experimental and computational classical electromagnetic models. The dependence of plasmonic enhancement on the spectral position of the excitation laser wavelength and the absorbance of the Pc molecules with respect to the wavelength specific near‐field enhancement is clearly demonstrated. A high ∼ 8 times enhancement is obtained with green laser (532 nm) at the LSPR due to the maximum near‐field enhancement at the resonance wavelength. [ABSTRACT FROM AUTHOR]

The development of nanozymes, artificial enzymes made from inorganic nanoparticles, is widely studied due to their affordability, durability, and strength. Gold nanoparticles (AuNPs) are employed to imitate peroxidase, glucose oxidase, lactate oxidase, superoxide dismutase, and catalase. The last one transforms intracellular hydrogen peroxide into molecular oxygen, whose deficiency is characteristic of the hypoxic tumor microenvironment. Thus, gold nanoparticles are thought to enhance the overall effectiveness of photodynamic therapy. However, the enzyme‐like activity of nanoparticles rapidly decreases in biological media, due to the aggregation and formation of the so‐called "protein corona". In this study, polymeric submicrocapsules loaded with AuNPs and a photodynamic dye are fabricated via Layer‐by‐Layer (LbL) assembly. The enhancement of photodynamic treatment efficacy by in situ production of oxygen by the catalase‐like effect of AuNPs is investigated. Polymeric capsules are thoroughly characterized in terms of physicochemical and catalytic properties, and as a proof of concept, their therapeutic potential is evaluated in vitro. Furthermore, encapsulated AuNPs shows significantly lower aggregation both upon storage and during the reaction course. The results shows that the polymer capsules, containing AuNPs and photodynamic dye, show significantly higher light‐induced cytotoxicity in comparison to the individual photodynamic dye, suggesting a synergistic effect between the formation of molecular oxygen by catalase‐like gold nanozymes and photodynamic action. [ABSTRACT FROM AUTHOR]

Antibacterial photodynamic therapy (a‐PDT) has emerged as a promising non‐invasive therapeutic modality that utilizes the combination of a photosensitive agent, molecular oxygen, and excitation light to generate reactive oxygen species (ROS), demonstrating remarkable activity against multidrug‐resistant bacterial infections. However, the effective use of conventional photosensitizers is significantly limited by a number of their shortcomings, namely, poor water solubility and low selectivity. Herein, we present a novel biocompatible water‐soluble nanocomposite based on hydrophobic tetraphenylporphyrin (TPP) molecules and hydrophilic ternary AgInS2/ZnS quantum dots incorporated into a chitosan matrix as an improved photosensitizer for a‐PDT. We demonstrated that TPP molecules could be successfully transferred into chitosan solution while remaining primarily in the form of monomers, which are capable of singlet oxygen generation. We performed a detailed analysis of the Förster resonance energy transfer (FRET) between quantum dots and TPP molecules within the nanocomposite and proposed the mechanism of the singlet oxygen efficiency enhancement via FRET. [ABSTRACT FROM AUTHOR]