Controllable Gold Nanocluster-Emulsion Interface for Direct Cell Penetration and Photothermal Killing

Gold nanoclusters cure implant infections by targeting biofilm

The biofilm-mediated implant infections pose a huge threat to human health. It is urgent to explore strategies to reverse this situation. Herein, we design 3-amino-1,2,4-triazole-5-thiol (ATT)-modified gold nanoclusters (AGNCs) to realize biofilm-targeting and near-infrared (NIR)-II light-responsive antibiofilm therapy. The AGNCs can interact with the bacterial extracellular DNA through the formation of hydrogen bonds between the amine groups on the ATT and the hydroxyl groups on the DNA. The AGNCs show photothermal properties even at a low power density (0.5 W/cm2) for a short-time (5 min) irradiation, making them highly effective in eradicating the biofilm with a dispersion rate up to 90 %. In vivo infected catheter implantation model demonstrates an exceptional high ability of the AGNCs to eradicate approximately 90 % of the bacteria encased within the biofilms. Moreover, the AGNCs show no detectable toxicity or systemic effects in mice. Our study suggests the great potential of the AGNCs for long-term prevention and elimination of the biofilm-mediated infections.

NIR and magnetism dual-response multi-core magnetic vortex nanoflowers for boosting magneto-photothermal cancer therapy

Due to the relatively low efficiency of magnetic hyperthermia and photothermal conversion, it is rather challenging for magneto-photothermal nanoagents to be used as an effective treatment during tumor hyperthermal therapy. The advancement of magnetic nanoparticles exhibiting a vortex-domain structure holds great promise as a viable strategy to enhance the application performance of conventional magnetic nanoparticles while retaining their inherent biocompatibility. Here, we report the development of Mn0.5Zn0.5Fe2O4 nanoflowers with ellipsoidal magnetic cores, and show them as effective nanoagents for magneto-photothermal synergistic therapy. Comparative studies were conducted on the heating performance of anisometric Mn0.5Zn0.5Fe2O4 (MZF) nanoparticles, including nanocubes (MZF-C), hollow spheres (MZF-HS), nanoflowers consisting of ellipsoidal magnetic cores (MZF-NFE), and nanoflowers consisting of needle-like magnetic cores (MZF-NFN). MZF-NFE exhibits an intrinsic loss parameter (ILP) of up to 15.3 N h m2 kg-1, which is better than that of commercial equivalents. Micromagnetic simulations reveal the magnetization configurations and reversal characteristics of the various MZF shapes. Additionally, all nanostructures displayed a considerable photothermal conversion efficiency rate of more than 18%. Our results demonstrated that by combining the dual exposure of MHT and PTT for hyperthermia treatments induced by MZF-NFE, BT549, MCF-7, and 4T1 cell viability can be significantly decreased by ∼95.7% in vitro.

Photofunctional Gold Nanocluster Composites for Bioapplications

Gold nanoclusters (AuNCs), with customized structures and diverse optical properties, are promising optical materials. Constructing composite systems by the assembly and incorporation of AuNCs can utilize their optical properties to achieve diagnostic and therapeutic applications in the biological field. Therefore, the exploration of the assembly behaviors of AuNCs and the enhancement of their performance has attracted widespread interest. In this review, we introduce multiple interactions and assembly modes that are prevalent in nanocomposites and microcomposites based on AuNCs. Then, the functions of AuNC composites for bioapplications are demonstrated in detail. These composite systems have inherited and enhanced the inherent optical performances of the AuNCs to meet diverse requirements for biological sensing and optical treatments. Finally, we discuss the prospects of AuNC composites and highlight the challenges and opportunities in biomedical applications.

Microemulsion-Assisted Self-Assembly of Indium Porphyrin Photosensitizers with Enhanced Photodynamic Therapy

Designing and constructing supramolecular photosensitizer nanosystems with highly efficient photodynamic therapy (PDT) is vital in the nanomedical field. Despite recent advances in forming well-defined superstructures, the relationship between molecular arrangement in nanostructures and photodynamic properties has rarely been involved, which is crucial for developing stable photosensitizers for highly efficient PDT. In this work, through a microemulsion-assisted self-assembly approach, indium porphyrin (InTPP) was used to fabricate a series of morphology-controlled self-assemblies, including nanorods, nanospheres, nanoplates, and nanoparticles. They possessed structure-dependent 1O2 generation efficiency. Compared with the other three nanostructures, InTPP nanorods featuring strong π-π stacking, J-aggregation, and high crystallinity proved to be much more efficient at singlet oxygen (1O2) production. Also, theoretical modeling and photophysical experiments verified that the intermolecular π-π stacking in the nanorods could cause a decreased singlet-triplet energy gap (ΔEST) compared with the monomer. This played a key role in enhancing intersystem crossing and facilitating 1O2 generation. Both in vitro and in vivo experiments demonstrated that the InTPP nanorods could trigger cell apoptosis and tumor ablation upon laser irradiation (635 nm, 0.1 W/cm2) and exhibited negligible dark toxicity and high phototoxicity. Thus, the supramolecular self-assembly strategy provides an avenue for designing high-performance photosensitizer nanosystems for photodynamic therapy and beyond.

Reconstituting Low-Density Lipoprotein with NIR-Absorbing Organic Photothermal Agents for Targeted Killing of Cancer Cells

Photothermal therapy (PTT) systems typically do not possess intrinsic tumor-targeting capability, resulting in indiscriminate thermal damage to both cancer and normal cells. Herein, a low-density lipoprotein (LDL)-based nanosystem (denoted as MTTQ@LDL) is reported for targeted photothermal killing of cancer cells. Such a nanosystem is fabricated by reconstituting the lipophilic core of LDL with an organic photothermal agent MTTQ. The reconstitution process improves the supramolecular photothermal effects of MTTQ assemblies, which contributes to the significantly enhanced photothermal conversion efficiency (41.3% vs. 16.2%). MTTQ@LDL can actively target LDL receptor-overexpressed cancer cells via receptor-mediated endocytosis, enabling the selective killing of cancer cells over normal cells (98% vs. 7%) post-NIR irradiation. Reconstituted LDL can serve as a promising platform for targeted delivery of functional materials, holding great promise in tumor eradication in vivo.

Multiple thermocycles followed by LAMP with only two primers for ultrasensitive colorimetric viral RNA testing and tracking at single-base resolution

Rapid, accurate and high throughput measurement of infectious viruses is an urgent need to prevent viral transmission. Loop-mediated isothermal amplification (LAMP) is an attractive isothermal amplification method for nucleic acid detection, especially for point-of-care (POC) testing, but it needs at least four primers and its sensitivity is also limited when integrating with visual detection methods. Herein, by designing only two primers to precisely recognize the four regions of the target, we developed a multiple thermocycles-based LAMP method (MTC-LAMP) for sensitive and specific testing and tracking of viral RNA. We also introduced a novel SYBR Green I (SG)-assisted stable colorimetric assay induced by the amplification products through the charge neutralization effect of positively charged SG toward gold nanoparticles (AuNPs). The ultralow nonspecific background of the double exponential amplification improved the detection sensitivity to near single-molecule level (1 aM, 3 copies in 5 μL solution), which was higher than RT-PCR and RT-LAMP. After adding AuNPs, a significant color difference between target and blank was immediately observed by naked eye. By introducing a peptide nucleic acid (PNA) clamp into our colorimetric MTC-LAMP assay, the specific distinguish of virus variants at single-base resolution was observed without the requirement of any equipment. This assay shows great potential for large-scale screening and tracking of the threatening viruses with ultrahigh sensitivity and pronounced colorimetric output, which is of great importance for pandemic control.

Green Synthesis of Antimicrobial Peptide-Protected Silver Nanoclusters with Regulated Antibacterial Behavior

The antibacterial system based on the silver element has been a very promising antibacterial material. However, the antibacterial activity of silver nanomaterials largely depends on their chemical composition and physical properties. Herein, we prepared ultrasmall silver nanoclusters by directly reducing silver ions with antimicrobial peptide in a green way. The positively charged peptide ligands drove the silver nanoclusters binding to bacteria by electrostatic attraction. Contrary to the large-sized silver nanomaterials, the ultrasmall silver nanoclusters were able to rapidly penetrate bacteria membranes via strong hydrophobic association, significantly promoting the generation of reactive oxygen species, and the subsequent high oxidative stress led to bacterial death. Moreover, the silver nanoclusters with antibacterial peptide ligand exhibited good stability, low cytotoxicity, and long-term antibacterial activity. Besides, synergistic enhancement of silver nanoclusters on antibacterial activity was observed. Therefore, the silver nanoclusters conjugated with the antimicrobial peptide can act as a synergistic antibacterial agent, in which their bio-interactions with bacteria have been regulated to achieve a rapid, long-lasting, and broad-spectrum antibacterial effect.