Multifunctional Plasmon-Tunable Au Nanostars and Their Applications in Highly Efficient Photothermal Inactivation and Ultra-Sensitive SERS Detection

The development and application in different fields of multifunctional plasmonic nanoparticles (NPs) have always been research hotspots. Herein, multi-tip Au nanostars (NSs) with an anisotropic structure were fabricated for the photothermal therapy (PTT) of bacteria and surface-enhanced Raman scattering (SERS) detection of pollutants. The size and localized surface plasmon resonance (LSPR) characteristics of Au NSs were adjusted by varying Au seed additions. In addition, photothermal conversion performance of Au NSs with various Au seed additions was evaluated. Photothermal conversion efficiency of Au NSs with optimal Au seed additions (50 μL) was as high as 28.75% under 808 nm laser irradiation, and the heat generated was sufficient to kill Staphylococcus aureus (S. aureus). Importantly, Au NSs also exhibited excellent SERS activity for the 4-mercaptobenzoic acid (4-MBA) probe molecule, and the local electromagnetic field distribution of Au NSs was explored through finite-difference time-domain (FDTD) simulation. As verified by experiments, Au NSs' SERS substrate could achieve a highly sensitive detection of a low concentration of potentially toxic pollutants such as methylene blue (MB) and bilirubin (BR). This work demonstrates a promising multifunctional nanoplatform with great potential for efficient photothermal inactivation and ultra-sensitive SERS detection.

MoS2-based nanocomposites for cancer diagnosis and therapy

Molybdenum is a trace dietary element necessary for the survival of humans. Some molybdenum-bearing enzymes are involved in key metabolic activities in the human body (such as xanthine oxidase, aldehyde oxidase and sulfite oxidase). Many molybdenum-based compounds have been widely used in biomedical research. Especially, MoS2-nanomaterials have attracted more attention in cancer diagnosis and treatment recently because of their unique physical and chemical properties. MoS2 can adsorb various biomolecules and drug molecules via covalent or non-covalent interactions because it is easy to modify and possess a high specific surface area, improving its tumor targeting and colloidal stability, as well as accuracy and sensitivity for detecting specific biomarkers. At the same time, in the near-infrared (NIR) window, MoS2 has excellent optical absorption and prominent photothermal conversion efficiency, which can achieve NIR-based phototherapy and NIR-responsive controlled drug-release. Significantly, the modified MoS2-nanocomposite can specifically respond to the tumor microenvironment, leading to drug accumulation in the tumor site increased, reducing its side effects on non-cancerous tissues, and improved therapeutic effect. In this review, we introduced the latest developments of MoS2-nanocomposites in cancer diagnosis and therapy, mainly focusing on biosensors, bioimaging, chemotherapy, phototherapy, microwave hyperthermia, and combination therapy. Furthermore, we also discuss the current challenges and prospects of MoS2-nanocomposites in cancer treatment.

PEGylated Phthalocyanine-Functionalized Graphene Oxide with Ultrahigh-Efficient Photothermal Performance for Triple-Mode Antibacterial Therapy

This study proposes a novel multifunctional synergistic antibacterial phototherapy technique for the rapid healing of bacteria-infected wounds. By binding PEGylated phthalocyanines to the surface of graphene oxide via noncovalent functionalization, the photothermal conversion efficiency of the obtained nanocomposites can be significantly increased, which shows that the sample temperature can achieve nearly 100 °C after only 10 min of 450 nm light illumination at a concentration ≥25 μg/mL. Moreover, the nanocomposites can rapidly generate singlet oxygen under 680 nm light irradiation and physically cut bacterial cell membranes. The triple effects are expected to obtain a synergistic antibacterial efficiency and reduce the emergence of bacterial resistance. After dual-light irradiation for 10 min, the generation of hyperthermia and singlet oxygen can cause the death of Gram-positive and Gram-negative bacteria. The results of an in vivo experiment revealed that the as-prepared nanocomposites combined with dual-light-triggered antibacterial therapy can effectively restrain the inflammatory reaction and accelerate the healing of bacteria-infected wounds. These were confirmed by the examination of pathological tissue sections and inflammatory factors in rats with bacteria-infected wounds. This nanotherapeutic platform is a potential photoactivated antimicrobial strategy for the prevention and treatment of bacterial infection.

Nanomaterial-Based Tumor Photothermal Immunotherapy

In recent years, photothermal therapy (PTT) particularly nanomaterial-based PTT is a promising therapeutic modality and technique for cancer tumor ablation. In addition to killing tumor cells directly through heat, PTT also can induce immunogenic cell death (ICD) to activate the whole-body anti-tumor immune response, including the redistribution and activation of immune effector cells, the expression and secretion of cytokines and the transformation of memory T lymphocytes. When used in combination with immunotherapy, the efficacy of nanomaterial-based PTT can be improved. This article summarized the mechanism of nanomaterial-based PTT against cancer and how nanomaterial-based PTT impacts the tumor microenvironment and induces an immune response. Moreover, we reviewed recent advances of nanomaterial-based photothermal immunotherapy and discussed challenges and future outlook.