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

Photothermal Miniemulsion Polymerization by Amphiphilic Gold Nanoclusters

Gold nanoclusters (AuNCs), which are approximately 2 nm in size, exhibit distinctive photophysical and catalytic properties, but their performance is often compromised by environmental factors. To mitigate these challenges, attempts have been made to incorporate AuNCs into polymer matrices to enhance their stability. Miniemulsion polymerization has proven to be an effective method for fabricating organic-inorganic composites. Here, we present a facile photothermal-assisted method for miniemulsion polymerization utilizing AuNCs, which serve as co-stabilizers of the emulsion and photothermal conversion agents. By grafting tryptamine onto hydrophilic AuNCs, the amphiphilic AuNCs were spontaneously adsorbed at the styrene/water interfaces, resulting in stable nanoemulsions. Taking advantage of the photothermal properties of surface-bounded AuNCs, rapid polymerization of styrene within the nanoemulsion was successfully initiated by external laser irradiation. The prepared nanocomposites inherited the photothermal activity of AuNCs and exhibited good photothermal stability and repeatability. This approach not only facilitates remote control of chemical reactions, but also optimizes the distribution of AuNCs within the final polymer matrix, thereby enabling the efficient synthesis of nanocomposites while exploiting the unique photofunctionality of AuNCs.

Metal-phenolic-network-coated gold nanoclusters for enhanced photothermal/chemodynamic/immunogenic cancer therapy

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, characterised by a short survival period, high malignancy, strong invasiveness, and high rates of recurrence and metastasis. Due to its unique molecular phenotype, TNBC is insensitive to endocrine therapy or molecular targeted therapy. The conventional treatment approach involves systemic chemotherapy for overall management; however, adjuvant chemotherapy after surgery has shown poor efficacy as residual lesions can easily lead to tumour recurrence. Therefore, there is an urgent need to find more effective treatment strategies. Herein, we designed a gold nanocluster coated with a metal-phenol formaldehyde network structure (AuNCs@PDA-Mn) for tumour Photothermal therapy and chemodynamic therapy (PTT and CDT), which induces systemic immune responses to suppress tumour metastasis. Experimental results show that after continuous irradiation for 10 min under an 808 nm laser (1.0W/cm2), AuNCs@PDA-Mn not only exhibits better tumour inhibition both in vitro and in vivo but also triggers stronger immune effects systemically. Therefore, this combined PTT and CDT treatment approach has great potential and provides a clinically relevant and valuable option for triple-negative breast cancer.

A Montmorillonite-Based Pickering Nanoemulsion for the Integration of Photothermal Therapy and NIR-Responsive Drug Delivery

Chemo/photothermal combination therapy is a promising and practical approach for cancer treatment which calls for certain nanovehicles to achieve the spatiotemporal co-occurrence of photothermal conversion and drug delivery. Herein, we developed a montmorillonite-based Pickering emulsion equipped with a near-infrared photothermal agent (indocyanine green, ICG) and anticarcinogen (paclitaxel, PTX). With both montmorillonite and ICG functioning as interfacial stabilizers, the Pickering emulsion showed good stability and nanoscale droplet size, which were favored for cellular applications. Due to the vast oil-water interface, where the majority of amphiphilic ICG was prone to distribute, the Pickering nanoemulsion could achieve a higher local concentration of ICG than the aqueous solution, therefore leading to a higher local photothermal performance under near-infrared irradiation. The Pickering nanoemulsion exhibited fast cell penetration, which promoted the photothermal therapeutic effect of ICG. Moreover, the inner phase of the Pickering nanoemulsion also facilitated the loading of PTX, further improving its killing efficacy against cancer cells under near-infrared irradiation, because the photothermal conversion of the Pickering nanoemulsion could not only cause heat damage by itself but also promote the loaded PTX to diffuse out and induce cell death. Therefore, this clay-based Pickering nanoemulsion as a nanovehicle could realize the synergy of chemo- and photothermal therapy.

Inflection of Resistive Switching Behavior in Atomically Precise Silver Cluster-Assembled Materials

Bottom-up design of electronic materials based on nanometer-sized building blocks requires precise control over their self-assembly process. Atomically precise metal nanoclusters (NCs) are the well-characterized building blocks for crafting tunable nanomaterials. Here, a solution-processed assembly of a newly synthesized molecular silver nanocluster (0 D Ag12-NC) into a 1D nanocluster chain (1 D Ag12-CAM) is mediated by 4,4'-bipyridine linker Both 0 D Ag12-NC and 1 D Ag12-CAM consist of Ag12 core that adopts the cuboctahedron geometry protected by organic ligands. The resistive switching devices are fabricated in a sandwich-like structure of ITO (Indium tin oxide)/X/Ag (where X is either 0 D Ag12-NC or 1 D Ag12-CAM). The device based on 1 D Ag12-CAM exhibited excellent resistive switching behaviour, enduring up to 1000 cycles and boasting a fivefold higher Ion/Ioff ratio compared to the device based on the molecular 0 D Ag12-NC nanocluster. Furthermore, the device based on 1 D Ag12-CAM demonstrated negative differential resistance (NDR) phenomena, achieving a peak-to-valley ratio of 2.34 with a switching efficiency of 23 Ns. This work highlights the importance of interconnecting molecular nanoclusters into 1D nanocluster chains for fine-tuning resistive memory properties in futuristic electronic appliances.

Intracellular Gold Nanocluster/Organic Semiconductor Heterostructure for Enhancing Photosynthesis

Photosynthetic microorganisms, which rely on light-driven electron transfer, store solar energy in self-energy carriers and convert it into bioenergy. Although these microorganisms can operate light-induced charge separation with nearly 100 % quantum efficiency, their practical applications are inherently limited by the photosynthetic energy conversion efficiency. Artificial semiconductors can induce an electronic response to photoexcitation, providing additional excited electrons for natural photosynthesis to improve solar conversion efficiency. However, challenges remain in importing exogenous electrons across cell membranes. In this work, we have developed an engineered gold nanocluster/organic semiconductor heterostructure (AuNCs@OFTF) to couple the intracellular electron transport chain of living cyanobacteria. AuNCs@OFTF exhibits a prolonged excited state lifetime and effective charge separation. The internalized AuNCs@OFTF permits its photogenerated electrons to participate in the downstream of photosystem II and construct an oriented electronic highway, which enables a five-fold increase in photocurrent in living cyanobacteria. Moreover, the binding events of AuNCs@OFTF established an abiotic-biotic electronic interface at the thylakoid membrane to enhance electron flux and finally furnished nicotinamide adenine dinucleotide phosphate. Thus, AuNCs@OFTF can be exploited to spatiotemporally manipulate and enhance the solar conversion of living cyanobacteria in cells, providing an extended nanotechnology for re-engineering photosynthetic pathways.

Modular Assembly of Photoactive Lipid Nanoparticles on Red Blood Cells toward Enhanced Phototherapy Efficacy

Photodynamic therapy has been developed as a promising treatment for malignant tumors, which inspires research into photosensitizers. However, the therapeutic efficacy of individual photosensitizers is often hampered by the physiological environment. The assembly of biological materials with synthetic molecules offers a strategy to enhance functionality while improving tolerance to varying physiological conditions. Herein, we present a biohybrid system for enhanced phototherapy efficacy through a simple two-step assembly process. Photoactive lipid nanoparticles were assembled based on synthesized conjugated molecules and lipophilic prodrugs, which were then modularly assembled with red blood cells (RBCs). Driven by hydrophobic and electrostatic interactions, hydrophobic conjugated molecules were efficiently incorporated into the RBCs, while lipophilic prodrugs were simultaneously inserted into the cell membranes. The engineered RBCs harnessed the natural oxygen transport capability, enabling the internal conjugated molecules to effectively produce reactive oxygen species (ROSs) even under oxygen-poor conditions. Meanwhile, the use of ROS-cleavable linkers in prodrugs enhanced drug release for chemotherapy, which is a perfect complement to photodynamic therapy. In vitro and in vivo experiments proved the improved phototherapy efficacy of the biohybrid system. Furthermore, the changes in aggregation directed Förster resonance energy transfer between conjugated molecules and fluorescent drugs provided a mechanism to track drug release from engineered RBCs. Therefore, the modular assembly of biohybrid systems can offer multiple functionalities required for phototherapy, on-demand drug release, and imaging.

An NIR-propelled janus nanomotor with enhanced ROS-scavenging, immunomodulating and biofilm-eradicating capacity for periodontitis treatment

Periodontitis is an inflammatory disease caused by bacterial biofilms, which leads to the destruction of periodontal tissue. Current treatments, such as mechanical cleaning and antibiotics, struggle to effectively address the persistent biofilms, inflammation, and tissue damage. A new approach involves developing a Janus nanomotor (J-CeM@Au) by coating cerium dioxide-doped mesoporous silica (CeM) with gold nanoparticles (AuNPs). This nanomotor exhibits thermophoretic motion when exposed to near-infrared (NIR) laser light due to the temperature gradient produced by the photothermal effects of asymmetrically distributed AuNPs. The NIR laser provides the energy for propulsion and activates the nanomotor's antibacterial properties, allowing it to penetrate biofilms and kill bacteria. Additionally, the nanomotor's ability to scavenge reactive oxygen species (ROS) can modulate the immune response and create a regenerative environment, promoting the healing of periodontal tissue. Overall, this multifunctional nanomotor offers a promising new approach for treating periodontitis by simultaneously addressing biofilm management and immune modulation with autonomous movement.

Tuning molecular assembly behavior to amplify the sonodynamic activity of porphyrins for efficient antibacterial therapy

Sonodynamic therapy (SDT) is a promising strategy to treat deep-seated bacterial infections with good tissue penetration and spatiotemporal controllability. However, the low ROS generation efficiency of current sonosensitizers limits the development of SDT. Herein, we report a porphyrin derivative, TAPyPP-2, the sonodynamic activity of which is enhanced with less oxygen dependence by tuning its molecular assembly behavior. TAPyPP-2 can spontaneously form an ultra-small nano-assembly with a diameter of 6 nm in water by conjugation with primary amine salt-decorated pyridinium via π-π staking. The ultra-small assembly behavior can lower the energy gap between singlet and triplet states to 0.01 eV and promote the separation of holes and electrons, which facilitates ROS generation under ultrasound irradiation, in particular type I ROS. The unique hydrophilic ratio and positive charges endow TAPyPP-2 with superior abilities to interact with Staphylococcus aureus, resulting in extremely high sonodynamic antibacterial activity. Therefore, TAPyPP-2 successfully kills Staphylococcus aureus bacteria in the enclosed cavity of synovial joint and achieves effective SDT of septic arthritis. This work is anticipated to motivate enormous interest in the development of efficient SDT.

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.