Revising catalytic “acceleration” of enzymes on citrate-capped gold nanoparticles

Biomimetic nanotechnology for cancer immunotherapy: State of the art and future perspective

Cancer continues to be a significant worldwide cause of mortality. This underscores the urgent need for novel strategies to complement and overcome the limitations of conventional therapies, such as imprecise targeting and drug resistance. Cancer Immunotherapy utilizes the body's immune system to target malignant cells, reducing harm to healthy tissue. Nevertheless, the efficacy of immunotherapy exhibits variation across individuals and has the potential to induce autoimmune responses. Biomimetic nanoparticles (bNPs) have transformative potential in cancer immunotherapy, promising improved accurate targeting, immune system activation, and resistance mechanisms, while also reducing the occurrence of systemic autoimmune side effects. This integration offers opportunities for personalized medicine and better therapeutic outcomes. Despite considerable potential, bNPs face barriers like insufficient targeting, restricted biological stability, and interactions within the tumor microenvironment. The resolution of these concerns is crucial in order to expedite the integration of bNPs from the research setting into clinical therapeutic uses. In addition, optimizing manufacturing processes and reducing bNP-related costs are essential for practical implementation. The present research introduces comprehensive classifications of bNPs as well as recent achievements in their application in cancer immunotherapies, emphasizing the need to address barriers for swift clinical integration.

Trametes versicolor laccase activity modulated by the interaction with gold nanoparticles

In this study, the impact of gold nanoparticles (AuNPs) on the structure and activity of laccase from Trametes versicolor (Lc) was described. Fluorescence experiments revealed that AuNPs efficiently quench Lc's tryptophan fluorescence by a static and dynamic process. By using differential scanning microcalorimetry and circular dichroism spectroscopy, it was determined how the concentration of nanoparticles and the composition of the medium affected the secondary structure of Lc. The data revealed that upon binding with AuNPs, conformational changes take place mainly in presence of high amounts of nanoparticles. The complex kinetic analysis unveiled the Lc activity enhancement at low concentrations of AuNPs as opposed to the concentrated regime, where it can be reduced by up to 55%. The Michaelis-Menten tests highlighted that the activity of the biocatalyst is closely related to the concentration of AuNPs, while the Selwyn analysis demonstrated that even in a concentrated regime of Lc it is not deactivated regardless of the amount of AuNPs added. The thermal parameters improved by twofold in the presence of low AuNPs concentration, whereas the activation energy increased with AuNPs content, implying that not all collisions are beneficial to the enzyme structure. The effect of AuNPs on the decomposition of a recalcitrant dye (naphthol green B, NG) by Lc was also evaluated, and the Michaelis-Menten model revealed that only the high AuNPs content influenced negatively the Lc activity. The isothermal titration calorimetry revealed that hydrogen bonds are the main intermolecular forces between Lc and AuNPs, while electrostatic interactions are responsible for NG adsorption to AuNPs. The results of the docking analysis show the binding of NG near the copper T1 site of Lc with hydrogen bonds, electrostatic and hydrophobic interactions. The findings of this work provide important knowledge for laccase-based bio-nanoconjugates and their use in the field of environmental remediation.

Capacitance-Based Biosensor for the Measurement of Total Loss of L-Amino Acids in Human Serum during Hemodialysis

In this paper, we present a biosensor based on a gold nanoparticle (AuNP)-modified Pt electrode with an adjusted membrane containing cross-linked L-amino acid oxidase for the detection and quantification of total L-amino acids. The designed biosensor was tested and characterized using the capacitance-based principle, capacitance measurements after electrode polarization, disconnection from the circuit, and addition of the respective amount of the analyte. The method was implemented using the capacitive and catalytic properties of the Pt/AuNP electrode; nanostructures were able to store electric charge while at the same time catalyzing the oxidation of the redox reaction intermediate H₂O₂. In this way, the Pt/AuNP layer was charged after the addition of analytes, allowing for much more accurate measurements for samples with low amino acid concentrations. The combined biosensor electrode with the capacitance-based measurement method resulted in high sensitivity and a low limit of detection (LOD) for hydrogen peroxide (4.15 μC/μM and 0.86 μM, respectively) and high sensitivity, a low LOD, and a wide linear range for L-amino acids (0.73 μC/μM, 5.5 μM and 25-1500 μM, respectively). The designed biosensor was applied to measure the relative loss of amino acids in patients undergoing renal replacement therapy by analyzing amino acid levels in diluted serum samples before and after entering/leaving the hemodialysis apparatus. In general, the designed biosensor in conjunction with the proposed capacitance-based method was clinically tested and could also be applied for the detection of other analytes using analyte-specific oxidases.