Nanotheranostic Application of Fluorescent Protein-Gold Nanocluster Hybrid Materials: A Mini-review

Gold nanostructures in melanoma: Advances in treatment, diagnosis, and theranostic applications

Melanoma, a lethal form of skin cancer, poses a significant challenge in oncology due to its aggressive nature and high mortality rates. Gold nanostructures, including gold nanoparticles (GNPs), offer myriad opportunities in melanoma therapy and imaging due to their facile synthesis and functionalization, robust stability, tunable physicochemical and optical properties, and biocompatibility. This review explores the emerging role of gold nanostructures and their composites in revolutionizing melanoma treatment paradigms, bridging the gap between nanotechnology and clinical oncology, and offering insights for researchers, clinicians, and stakeholders. It begins by elucidating the potential of nanotechnology-driven approaches in cancer therapy, highlighting the unique physicochemical properties and versatility of GNPs in biomedical applications. Various therapeutic modalities, including photothermal therapy, photodynamic therapy, targeted drug delivery, gene delivery, and nanovaccines, are discussed in detail, along with insights from ongoing clinical trials. In addition, the utility of GNPs in melanoma imaging and theranostics is explored, showcasing their potential in diagnosis, treatment monitoring, and personalized medicine. Furthermore, safety considerations and potential toxicities associated with GNPs are addressed, underscoring the importance of comprehensive risk assessment in clinical translation. Finally, the review concludes by discussing current challenges and future directions, emphasizing the need for innovative strategies to maximize the clinical impact of GNPs in melanoma therapy.

Fluorescent ovalbumin-functionalized gold nanocluster as a highly sensitive and selective sensor for relay detection of salicylaldehyde, Hg(II) and folic acid

A sensitive and selective relay-based scheme for the detection of salicylaldehyde, Hg2+, and folic acid (FA) has been demonstrated using fluorescent ovalbumin functionalized gold nanoclusters (OVA-AuNCs, λem = 655 nm) in this article. The OVA-AuNCs were conjugated to salicylaldehyde via an imine linkage to form Salic_OVA-AuNCs conjugate. The molecular docking study reveals that multiple functional groups and amino acid residues are involved in the interaction between salicylaldehyde and the OVA-AuNCs. The coupling of salicylaldehyde with OVA-AuNCs results in fluorescence quenching at 655 nm and concomitant formation of an emission band at 500 nm, which have leveraged to detect salicylaldehyde down to 2.02 µM. Following that, the Salic_OVA-AuNCs has been used for the detection of Hg2+ and FA. Several processes, such as internal charge transfer (ICT), photoinduced electron transfer (PET) and metallophilic interactions, are involved between the Salic_OVA-AuNCs nanoprobe and the analytes, which allowed to detect Hg2+ and FA down to 0.13 nM and 0.11 nM, respectively. The Salic_OVA-AuNCs nanoprobe has an additional naked-eye utility when applied to paper-strip sensing strategy for Hg2+ and FA detection.

Size-dependent effects of the thermal transport at gold nanoparticle-water interfaces

The transfer of heat from a plasmonic nanoparticle to its water environment has numerous applications in the fields of solar energy conversion and photothermal therapies. We use non-equilibrium molecular dynamics to investigate the size-dependent effects of the interfacial thermal conductance of gold nanoparticles immersed in water and of tunable wettability. The interfacial thermal conductance is found to increase when the nanoparticle size decreases. We rationalize such a behavior with a generalized acoustic model, where the interfacial bonding decreases with the nanoparticle size. The analysis of the interfacial thermal spectrum reveals the importance of the low frequency peak of the nanoparticle spectrum as it matches relatively well the oxygen peak in the vibrational spectrum. However, by reducing the nanoparticle size, the low frequency peak is exacerbated, explaining the enhanced heat transfer observed for small nanoparticles. Finally, we assess the accuracy of continuum heat transferequations to describe the thermal relaxation of small nanoparticles with initial high temperatures.We show that, before the nanoparticle looses its integrity, the continuum model succeed in describing with small percentage deviations the molecular-dynamics data. This work brings a simple methodology to understand, beyond the plasmonic nanoparticles, thermal boundary conductance between a nanopartice and its environment.

Immunofluorescent-aggregation assay based on anti-Salmonella typhimurium IgG-AuNCs, for rapid detection of Salmonella typhimurium

Sensitive and rapid detection of pathogenic bacteria plays an important role in avoiding food poisoning. However, the practical application value of conventional assays for detection of foodborne bacteria, are limited by major drawbacks; these include the laboriousness of pure culture preparation, complexity of DNA extraction for polymerase chain reaction, and low sensitivity of enzyme-linked immunosorbent assay. Herein, we designed a non-complex strategy for the sensitive, quantitative, and rapid detection of Salmonella typhimurium with high specificity, using an anti-Salmonella typhimurium IgG-AuNC-based immunofluorescent-aggregation assay. Salmonella typhimurium was agglutinated with fluorescent anti-Salmonella typhimurium IgG-AuNC on a glass slide, and observed using a fluorescence microscope with photoexcitation and photoemission at 560 nm and 620 nm, respectively. Under optimized reaction conditions, the AuNC-based immunofluorescent-aggregation assay had a determination range between 7.0 × 10³ and 3.0 × 10⁸ CFU/mL, a limit of detection of 1.0 × 10³ CFU/mL and an assay response time of 3 min. The technique delivered good results in assessing real samples.

Silver Nanoparticle-Mediated Synthesis of Fluorescent Thiolated Gold Nanoclusters

A new strategy using silver nanoparticles (Ag NPs) to synthesize thiolated Au NCs is demonstrated. The quasi-spherical Ag NPs serve as a platform, functioning as a reducing agent for Au (III) and attracting capping ligands to the surface of the Ag NPs. Glutathione disulfide (GSSG) and dithiothreitol (DTT) were used as capping ligands to synthesize thiolated Au NCs (glutathione-Au NCs and DTT-Au NCs). The glutathione-Au NCs and DTT-Au NCs showed red color luminance with similar emission wavelengths (630 nm) at an excitation wavelength of 354 nm. The quantum yields of the glutathione-Au NCs and DTT-Au NCs were measured to be 7.3% and 7.0%, respectively. An electrophoretic mobility assay showed that the glutathione-Au NCs moved toward the anode, while the DTT-Au NCs were not mobile under the electric field, suggesting that the total net charge of the thiolated Au NCs is determined by the charges on the capping ligands. The detection of the K_SV values, 26 M⁻¹ and 0 M⁻¹, respectively, revealed that glutathione-Au NCs are much more accessible to an aqueous environment than DTT-Au NCs.