Recent Advancements on Photothermal Conversion and Antibacterial Applications over MXenes-Based Materials

Photothermal/photodynamic synergistic antibacterial Nanocellulose film modified with antioxidant MXene-PANI Nanosheets

TEMPO-CNF film modified by two-dimension transition metal MXene has certain antibacterial properties. However, the problem of long-lasting stability greatly restricts the feasibility of long-term use of the composite film. Here, we introduced polyaniline (PANI) as a modifying molecule, which was electrostatically adsorbed on the surface of the MXene nanosheets to prevent its self-stacking and delay its oxidation. The modified MXene could still maintain >85 % stability after 30 days of room temperature storage. The MXene-PANI nanocellulose (MXP/CNF) film was further prepared by combining electrostatic attraction and hydrogen bonding interactions. Thanks to the synergistic effects of the photothermal conversion and photodynamic of MXene and PANI themselves, as well as the high light-trapping properties of the heterostructures, the photothermal and photodynamic efficiencies of the MXP/CNF film were greatly improved. Under the irradiation of 808 nm near-infrared light at 1.5 W/cm2, the MXP/CNF film reached a temperature of 132.9 °C within 20 s. Meanwhile, reactive oxygen species are generated to degrade 55 % of crystalline violet by modified MXene composite film under light irradiation. Compared to 15 % bacterial survival on cellulose film not modified with PANI, S. aureus and E. coli were completely killed on MXP/CNF film under light conditions. The prepared thin film materials exhibit low cytotoxicity, highlighting their potential applications in biomedicine and desalination.

Epsilon-polylysine microneedle potentiating MXene-mediated photothermal ablation for combating antibiotic-resistant bacterial infections

Antimicrobial peptides show promise in enhancing photothermal therapy, but their application is often limited by the challenge of constructing a delivery system that balances efficacy and safety. Our research demonstrated that the bactericidal efficacy of V2C MXene-mediated photothermal therapy is enhanced in a concentration-dependent relationship with the introduction and coating of the antimicrobial peptide ε-polylysine (EPL). EPL exhibited a dual role in enhancing bacterial binding and disrupting bacterial membranes, thereby increasing heat transfer efficiency and reducing bacterial resistance to photothermal ablation. The core strategy of this study was to exploit the combined membranolytic-photothermal effect of EPL and V2C by extensively applying EPL while regulating V2C nanosheets usage to prevent overheating. This approach aims to achieve potent bactericidal efficacy through photothermal therapy below 60 °C. Consequently, we developed dissolving microneedles incorporated with V2C nanosheets, where EPL served as the antimicrobial agent and primary matrix, increasing its loading capacity and minimizing the need for inactive excipients. Notably, this microneedle achieved a 99.9 % reduction in the abundance of methicillin-resistant Staphylococcus aureus on infected skin after a single application and resulted in a 92-fold reduction in the bacterial load compared to the group treated with commercial Bactroban ointment, with no apparent toxicity to the mice.

Photothermal-responsive nanocomposite injectable hydrogel capable of programed peroxidase-mimicking catalysis and immunomodulation and revascularization enables efficient drug-resistant bacterial elimination and comprehensive tissue regeneration

Intractable infected wound caused by drug-resistant bacteria remains a severe healthcare problem. Reactive oxygen species (ROS)-based nanocatalytic therapy (ROS-NT) is harnessed to combat drug-resistant bacterial infection. However, it can also cause immune imbalance and excessive inflammatory responses, postponing subsequent wound healing process. Herein, a multifunctional ultrathin medium entropy metal oxides (UMEMOs)-based photothermal-responsive injectable hydrogel (UMEMOs/PF-MAL) was constructed, which is capable of efficient ROS-producing catalysis, immunomodulation, and revascularization. UMEMOs/PF-MAL can further provide an effective spatiotemporal therapy with programmed anti-infection and pro-healing effects to overcome drug-resistant bacterial infected wound. The incorporation of UMEMOs in injectable hydrogel not only endows UMEMOs/PF-MAL hydrogel with excellent peroxidase (POD)-mimicking activity and near infrared (NIR)-triggered photothermal conversion property, but also significantly improves its sol-gel properties. Moreover, UMEMOs/PF-MAL hydrogel can provide favorable release of Mg2+ and Cu2+, allowing a synergistic effect of immunomodulation, anti-inflammatory, and angiogenesis during pro-healing process. Under triggering with a low level of exogenous hydrogen peroxide (H2O2) and NIR irradiation, the photothermal-enhanced POD-like activity of UMEMOs/PF-MAL hydrogel enables efficient catalytic generation of hydroxyl radical (OH) at wound sites, which can easily permeate bacteria due to the local photothermal effect, killing drug-resistant bacteria and destroying biofilms. Following the cessation of H2O2 administration, Mg2+ released from UMEMOs/PF-MAL hydrogel causes the polarization of pro-inflammatory M1 to anti-inflammatory M2 macrophages, thereby reducing the inflammatory response and promoting tissue remodeling. Meanwhile, Cu2+ release boosts angiogenesis, and mild photothermal effect improves local blood oxygen circulation and alleviates inflammation, further accelerating wound healing. Therefore, this work offers a multifunctional UMEMOs/PF-MAL hydrogel with programmed anti-infection and pro-healing effects, achieving an efficient spatiotemporal therapy and the optimum therapeutic effect for drug-resistant bacteria infected wound.

MXenes in healthcare: synthesis, fundamentals and applications

Since their discovery over a decade ago, MXenes have transformed the field of "materials for healthcare", stimulating growing interest in their healthcare-related applications. These developments have also driven significant advancements in MXenes' synthesis. This review systematically examines the synthesis of MXenes and their applications in sensing and biomedical fields, underscoring their pivotal role in addressing critical challenges in modern healthcare. We describe the experimental synthesis of MXenes by combining appropriate laboratory modules with the mechanistic principles underlying each synthesis step. In addition, we provide extensive details on the experimental parameters, critical considerations, and essential instructions for successful laboratory synthesis. Various healthcare applications including sensing, biomedical imaging, synergistic therapies, regenerative medicine, and wearable devices have been explored. We further highlight the emerging trends of MXenes, viz., their role as nanovehicles for drug delivery, vectors for gene therapy, and tools for immune profiling. By identifying the important parameters that define the utility of MXenes in biomedical applications, this review outlines strategies to regulate their biomedical profile, thereby serving as a valuable guide to design MXenes with application-specific properties. The final section integrates experimental research with theoretical studies to provide a comprehensive understanding of the field. It examines the role of emerging technologies, such as artificial intelligence (AI) and machine learning (ML), in accelerating material discovery, structure-property optimization, and automation. Complemented by detailed supplementary information on synthesis, stability, biocompatibility, environmental impact, and theoretical insights, this review offers a profound knowledge base for understanding this diverse family of 2D materials. Finally, we compared the potential of MXenes with that of other 2D materials to underscore the existing challenges and prioritize interdisciplinary collaboration. By synthesizing key studies from its discovery to current trends (especially from 2018 onward), this review provides a cohesive assessment of MXene synthesis with theoretical foundations and their prospects in the healthcare sector.

MXene-based nanosheet for enhanced glioma therapy via photonic hyperthermia to boost the abscopal effect of radioimmunotherapy

Radiotherapy (RT) effectiveness is limited by low DNA damage in tumor cells, surrounding tissue harm, and tumor radioresistance with active DNA repair. Herein, we have engineered a two-dimensional nanomaterial consisting of MXene nanosheets at its core, coated with gold nanorods and a cisplatin shell, and further modified with polyvinyl alcohol, referred to as APMP. The APMP exploits its distinctive electronic properties and photothermal effects to augment radiosensitivity and impede DNA damage repair mechanisms. In vitro experiments demonstrate that APMP elevates reactive oxygen species (ROS) production to approximately 2.6 times higher than that achieved with radiotherapy alone, thereby significantly enhancing the sensitivity to radiotherapy. Combining APMP with photothermal therapy (PTT) and RT is a promising glioblastoma treatment strategy, achieving tumor destruction via localized hyperthermia and overcoming radioresistance. This approach achieves precise tumor targeting, reducing side effects and enhancing therapeutic response in preclinical models. The novel core-shell design enables potent radiotherapy-specific radiosensitizers that drive immunogenic cell death, enhancing glioblastoma combination immunotherapy. This universal strategy heralds a new era in integrating radiotherapy sensitizers with immunotherapy.

MXene-Integrated Responsive Hydrogel Microneedles for Oral Ulcers Healing

Glucocorticoids such as dexamethasone have shown promising therapeutic effects in conquering oral ulcers. Challenges in this area are focused on enhancing the localized curative effects and responsive release. Herein, we presented a novel MXene-integrated responsive hydrogel microneedle delivering dexamethasone to promote the healing of oral ulceration. By loading MXene, the hydrogel microneedles enable NIR (Near Infrared)-responsive release of the inner dexamethasone for inflammation control and tissue regeneration. In addition, the MXene-induced local hyperthermia could inhibit the bacteria, preventing the possible infection of ulcer lesions in the oral cavity. Based on these features, we demonstrated that our strategy could relieve local inflammation, promote tissue reconstruction, and accelerate wound healing in rat oral ulcer models. Overall, these NIR-responsive MXene-integrated hydrogel microneedles show significant promise in promoting ulcer healing and bring new ways for oral disease treatment.

Yolk-Shell CoNi@N-Doped Carbon-CoNi@CNTs for Enhanced Microwave Absorption, Photothermal, Anti-Corrosion, and Antimicrobial Properties

The previous studies mainly focused on improving microwave absorbing (MA) performances of MA materials. Even so, these designed MA materials were very difficult to be employed in complex and changing environments owing to their single-functionalities. Herein, a combined Prussian blue analogues derived and catalytical chemical vapor deposition strategy was proposed to produce hierarchical cubic sea urchin-like yolk-shell CoNi@N-doped carbon (NC)-CoNi@carbon nanotubes (CNTs) mixed-dimensional multicomponent nanocomposites (MCNCs), which were composed of zero-dimensional CoNi nanoparticles, three-dimensional NC nanocubes and one-dimensional CNTs. Because of good impedance matching and attenuation characteristics, the designed CoNi@NC-CoNi@CNTs mixed-dimensional MCNCs exhibited excellent MA performances, which achieved a minimum reflection loss (RLmin) of -71.70 dB at 2.78 mm and Radar Cross section value of -53.23 dB m2. More importantly, the acquired results demonstrated that CoNi@NC-CoNi@CNTs MCNCs presented excellent photothermal, antimicrobial and anti-corrosion properties owing to their hierarchical cubic sea urchin-like yolk-shell structure, highlighting their potential multifunctional applications. It could be seen that this finding not only presented a generalizable route to produce hierarchical cubic sea urchin-like yolk-shell magnetic NC-CNTs-based mixed-dimensional MCNCs, but also provided an effective strategy to develop multifunctional MCNCs and improve their environmental adaptabilities.

A flexible multifunctional sensor with a conductive network based on silk nanofibers and MXene for monitoring physiological activity, capacitive pens, photothermal conversion and antibacterial

Flexible electronic sensors that can capture subtle physical, chemical and biological signals and generate real-time stimulus responses are of great importance in the fields of human-computer interaction, biomedicine, etc. Herein, a multifunctional sensing hydrogel was developed by tightly adhering two-dimensional rigid conductive MXene nanosheets to the surface of vimineous silk nanofibers (SNFs) and assembling them into an SNF@MXene network structure. Polyvinyl alcohol (PVA) was then in situ polymerized in SNF@MXene as a filling matrix. MXene nanosheets were attached to the SNF network skeleton, avoiding the settlement and aggregation of MXene and forming a PSM composite hydrogel with a uniform and dense conductive network. The designed PSM hydrogel-based sensor showed excellent mechanical properties (tensile strength = 5.07 MPa), wide operating range (700.6 %), high sensitivity (gauge factor = 8.2), high electrical conductivity (1.64 S m-1), and adhesion. The sensor could detect various physiological activities of the human body. In addition, it also showed the application potential in speech recognition, capacitive pen, etc. PSM exhibited excellent photothermal conversion efficiency. It could be rapidly heated to 82.8 °C under NIR irradiation and used for photothermal therapy. This study provides a simple conductive network design strategy for the fabrication of flexible electronic devices with multiple functions.

Siderophore-Functionalized Nanodrug for Treating Antibiotic-Resistant Bacteria

The development of nanodrugs targeting multidrug-resistant bacteria, while sparing the beneficial constituents of the microbiome, has emerged as a promising approach to combat disease and curb the rise of antimicrobial resistance. In this investigation, we devised a siderophore-functionalized nanodrug based on a gold nanoparticle construct (AuNP-NSC; Gold nanoparticle_N-heterocyclic_Siderophore_Cyanine7), offering an innovative treatment modality against drug-resistant bacterial pathogens. As a proof of concept, the efficacy of this nanodrug delivery and antimicrobial therapy was evaluated against the notoriously resistant bacterium P. aeruginosa. N-Heterocyclic carbenes (NHCs) exhibit a strong affinity for transition metals, forming highly stable complexes resistant to ligand displacement. The entry of siderophore-conjugated nanodrugs into bacteria is facilitated through specific receptors on the outer membrane. In our study, AuNP-NSC was specifically targeted and imported into resistant Gram-negative P. aeruginosa via binding with ferric iron. Treatment with the developed nanodrug significantly inhibited the proliferation of antibiotic-resistant P. aeruginosa, reducing bacterial counts by more than 95% and mitigating drug resistance. Furthermore, AuNP-NSC markedly diminished P. aeruginosa-induced skin lesions and forestalled systemic organ failure triggered by secondary sepsis in mouse models. These findings underscore the potential of nanodrugs as specialized therapeutic agents for the management of antibiotic-resistant bacterial infections.

An overview of the use of non-titanium MXenes for photothermal therapy and their combinatorial approaches for cancer treatment

Since the initial publication on the first Ti3C2T x MXene in 2011, there has been a significant increase in the number of reports on applications of MXenes in various domains. MXenes have emerged as highly promising materials for various biomedical applications, including photothermal therapy (PTT), drug delivery, diagnostic imaging, and biosensing, owing to their fascinating conductivity, mechanical strength, biocompatibility and hydrophilicity. Through surface modification, MXenes can mitigate cytotoxicity, enhance biological stability, and improve histocompatibility, thereby enabling their potential use in in vivo biomedical applications. MXenes are also known for their ability to absorb light in the near-infrared (NIR) region and generate heat by localised surface plasmon resonance (LSPR) effects and electron-phonon coupling. Optical excitation laser pulses result in hot photocarrier distribution in MXenes, which quickly transfers surplus energy to the crystal lattice and results in the internal conversion of light into heat with nearly 100% efficiency. The relaxation of hot carrier distribution by electron-phonon interactions leads to the cooling of the lattice by dissipating thermal energy to the surrounding environment. This heating effect of MXenes makes them potential photothermal agents (PTAs), particularly for PTT applications. The adjustable surface of MXenes and their high surface area-to-volume ratios are ideal for the combinatorial approach of PTT along with drug delivery, photodynamic therapy (PDT), bone regeneration and other applications. Since non-Ti MXenes are more biocompatible than Ti MXenes, they are promising candidates for different biomedical applications. This comprehensive review provides a concise overview of the current research patterns, properties, and biomedical applications of non-Ti MXenes, particularly in PTT and its combinatorial approaches.

A tactfully designed photothermal agent collaborating with ascorbic acid for boosting maxillofacial wound healing

Maxillofacial injuries that may cause severe functional and aesthetic damage require effective and immediate management due to continuous exposure to diverse microbial populations. Moreover, drug resistance, biofilm formation, and oxidative stress significantly impede timely bacterial removal and immune function, making the exploration of advanced materials for maxillofacial wound healing an appealing yet highly challenging task. Herein, a near-infrared photothermal sterilization agent was designed, encapsulated with liposomes and coated with ascorbic acid known for its antioxidant and immune-regulatory functions. The resulting nanoparticles, 4TPE-C6T-TD@AA, effectively neutralize reactive oxygen species generated by lipopolysaccharides, facilitate the conversion of pro-inflammatory M1 macrophages to anti-inflammatory M2 macrophages, and eliminate >90% of Staphylococcus aureus and Escherichia coli by disrupting bacterial physiological functions upon exposure to 808 nm laser irradiation. In vivo experiments demonstrate that 4TPE-C6T-TD@AA rapidly eliminates bacteria from infected wounds in the maxillofacial region of rats, and significantly promotes healing in S. aureus-infected wounds by enhancing collagen formation and modulating the inflammatory microenvironment. In conclusion, this study presents a promising therapeutic strategy for effectively combating bacterial infections and excessive inflammation in treating maxillofacial injuries.

Biomimetic Micro-Nanostructured Evaporator with Dual-Transition-Metal MXene for Efficient Solar Steam Generation and Multifunctional Salt Harvesting

Solar-driven interfacial evaporation is one of the most attractive approaches to addressing the global freshwater shortage. However, achieving an integrated high evaporation rate, salt harvesting, and multifunctionality in evaporator is still a crucial challenge. Here, a novel composite membrane with biomimetic micro-nanostructured superhydrophobic surface is designed via ultrafast laser etching technology. Attractively, the double-transition-metal (V1/2Mo1/2)2CTx MXene nanomaterials as a photothermal layer, exhibiting the enhanced photothermal conversion performance due to elevated joint densities of states, which enables high populations of photoexcited carrier relaxation and heat release, provides a new insight into the photothermal conversion mechanism for multiple principal element MXene. Hence, the (V1/2Mo1/2)2CTx MXene-200 composite membrane can achieve a high evaporation rate of 2.23 kg m-2 h-1 under one sun, owing to the enhanced "light trap" effect, photothermal conversion, and high-throughput water transfer. Synergetically, the membrane can induce the directed precipitation of salt at the membrane edge, thus enabling salt harvesting for recycling and zero-emission of brine water. Moreover, the composite membrane is endowed with excellent multifunctionality of anti-/de-icing, anti-fouling, and antibacterial, overcoming the disadvantage that versatility is difficult to be compatible. Therefore, the evaporator and the promising strategy hold great potential for the practical application of solar evaporation.

Toward Efficient Utilization of Photogenerated Charge Carriers in Photoelectrochemical Systems: Engineering Strategies from the Atomic Level to Configuration

Photoelectrochemical (PEC) systems are essential for solar energy conversion, addressing critical energy and environmental issues. However, the low efficiency in utilizing photogenerated charge carriers significantly limits overall energy conversion. Consequently, there is a growing focus on developing strategies to enhance photoelectrode performance. This review systematically explores recent advancements in PEC system modifications, spanning from atomic and nanoscopic levels to configuration engineering. We delve into the relationships between PEC structures, intrinsic properties, kinetics of photogenerated charge carriers, and their utilization. Additionally, we propose future directions and perspectives for developing more efficient PEC systems, offering valuable insights into potential innovations in the field.

External Stimuli-Responsive Strategies for Surface Modification of Orthopedic Implants: Killing Bacteria and Enhancing Osteogenesis

Bacterial infection and insufficient osteogenic activity are the main causes of orthopedic implant failure. Conventional surface modification methods are difficult to meet the requirements for long-term implant placement. In order to better regulate the function of implant surfaces, especially to improve both the antibacterial and osteogenic activity, external stimuli-responsive (ESR) strategies have been employed for the surface modification of orthopedic implants. External stimuli act as "smart switches" to regulate the surface interactions with bacteria and cells. The balance between antibacterial and osteogenic capabilities of implant surfaces can be achieved through these specific ESR manifestations, including temperature changes, reactive oxygen species production, controlled release of bioactive molecules, controlled release of functional ions, etc. This Review summarizes the recent progress on different ESR strategies (based on light, ultrasound, electric, and magnetic fields) that can effectively balance antibacterial performance and osteogenic capability of orthopedic implants. Furthermore, the current limitations and challenges of ESR strategies for surface modification of orthopedic implants as well as future development direction are also discussed.

Synergetic antibacterial nanosheet based on Ti3C2Tx photothermal therapy and cationic polymer to eradicate drug-resistant bacterial biofilms

Drug-resistant bacteria infection and biofilm formation on the wound still pose a tremendous challenge in post-antibiotic era. It has been proposed that multimode synergetic antibacterial strategies may be employed to eradicate drug-resistant bacteria and biofilms effectively. In this study, we synthesized non-invasive antibacterial two-dimension (2D) composite nanosheet BPG using Ti3C2Tx MXene and cationic borneol-guanidine based polymers (B-PGMA-Gu) via simple electrostatically co-assemble. BPG can target bacteria and efficiently eliminate Gram-positive bacteria Staphylococcus aureus (S. aureus), Gram-negative bacteria Escherichia coli (E. coli), and methicillin-resistant Staphylococcus aureus (MRSA) under 808 nm radiation. By combining the photothermal properties of Ti3C2Tx MXene and the excellent membrane penetration ability of B-PGMA-Gu, MRSA biofilms can be effectively removed at 100 μg mL-1 under laser irradiation, resulting in a bactericidal efficiency of 99.1%. This method offers a more effective and rapid non-antibiotic method for removing biofilms.

Photodynamic therapy with NIR-II probes: review on state-of-the-art tools and strategies

In 2022 10% of the world's population was aged 65+, and by 2100 this segment is expected to hit 25%. These demographic changes place considerable pressure over healthcare systems worldwide, which results in an urgent need for accurate, inexpensive and non-invasive ways to treat cancers, a family of diseases correlated with age. Among the therapeutic tools that gained important attention in this context, photodynamic therapies (PDT), which use photosensitizers to produce cytotoxic substances for selectively destroying tumor cells and tissues under light irradiation, profile as important players for next-generation nanomedicine. However, the development of clinical applications is progressing at slow pace, due to still pending bottlenecks, such as the limited tissue penetration of the excitation light, and insufficient targeting performance of the therapeutic probes to fully avoid damage to normal cells and tissues. The penetration depth of long-wavelength near infrared (NIR) light is significantly higher than that of short-wavelength UV and visible light, and thus NIR light in the second window (NIR-II) is acknowledged as the preferred phototherapeutic means for eliminating deep-seated tumors, given the higher maximum permissible exposure, reduced phototoxicity and low autofluorescence, among others. Upon collective multidisciplinary efforts of experts in materials science, medicine and biology, multifunctional NIR-II inorganic or organic photosensitizers have been widely developed. This review overviews the current state-of-the art on NIR-II-activated photosensitizers and their applications for the treatment of deep tumors. We also place focus on recent efforts that combine NIR-II activated PDT with other complementary therapeutic routes such as photothermal therapy, chemotherapy, immunotherapy, starvation, and gas therapies. Finally, we discuss still pending challenges and problems of PDT and provide a series of perspectives that we find useful for further extending the state-of-the art on NIR-II-triggered PDT.

Versatile synthesis of cellulose film with excellent electrothermal/photothermal dual responsiveness by introducing MXene and small molecule self-assembled nanosphere

Plant-derived biomaterials have great application prospects in solving environmental pollution and sustainable resource utilization, but the insufficient mechanical strength and lack of functional responsiveness often limit their further development. Inspired by natural small molecules functionalization, a vacuum-assisted filtration nanofibrillated cellulose (NFC)-based film with excellent antibacterial properties, mechanical strength, and electrothermal/photothermal dual-responsiveness was fabricated. As a natural bioactive molecule, antibacterial cinnamaldehyde (CA) is grafted onto tannic acid (TA) rich in pyrogallols via a small molecule self-assembly strategy, and then co-assembled with zinc acetate (ZA) through ion crosslinking to synthesize the functional TACA@ZA nanospheres. After incorporating the MXene and TACA@ZA, an inorganic-organic 3D network system was established in the NFC matrix through dynamic intermolecular hydrogen bonding and strong ionic cross-linking. The mechanical strength and toughness of hybrid composites are remarkably improved by 83.6 % and 418.9 %, respectively. Due to the synergistic effects of MXene and TACA@ZA, the designed NFC-based film also shows significantly enhanced antibacterial activity, UV-blocking ability, as well as photothermal and electrothermal performance. This bioinspired small molecule functionalization strategy opens an innovative design concept for the fabrication of multirole NFC-based biomaterials, which has great application prospects in the commercial fields of multifunctional adhesives, electronic devices, UV shielding coatings, and antibacterial materials.

Photothermal controlled antibacterial Ta4C3Tx-AgNPs/nanocellulose bioplastic food packaging

Uncontrolled antibacterial, insufficient barrier and low strength are the bottlenecks of food packaging applications. Herein, Ta4C3Tx nanosheet as a template was used to prepare Ta4C3Tx immobilized silver nanoparticles (Ta4C3Tx-AgNPs), which was compounded with nanocellulose to obtain high-strength and high barrier controllable bactericidal nanocellulose-based bioplastic packaging (CTa-Ag). The results indicated that due to the hydrogen bonding between nanocellulose and Ta4C3Tx, the bridging effect of QCS (quaternized chitosan) and the filling of Ta4C3Tx-AgNPs, the CTa-Ag had tightly stacked microstructure, which endowed them with excellent mechanical properties (4.0 GPa), ultra-low oxygen permeability (0.009 cm3/m2·d·atm) and stable photothermal conversion efficiency. Importantly, the packaging exhibits the ability to control the release of antibacterial active ingredients. Moreover, the synergistic effects of controllable release of nano active factors, photothermal and photocatalysis in CTa-Ag gave it long-lasting antibacterial properties. This study brings new insights into the design and manufacture of multifunctional, controllable and long-lasting antibacterial bioplastic food packaging.

Recent progress in hydrogels combined with phototherapy for bacterial infection: A review

Phototherapy has become one of the most effective antibacterial methods due to its associated lack of drug resistance and its good antibacterial effect. For the purpose of avoiding the aggregation and premature release of photosensitive/photothermal agents during phototherapy, they can be mixed into three-dimensional hydrogels. The combination of hydrogels and phototherapy combines the merits of both hydrogels and phototherapy, overcomes the disadvantages of traditional antibacterial methodologies, and has broad application prospects. This review presents recent advancements in phototherapeutic antibacterial hydrogels including photodynamic antibacterial hydrogels, photothermal antibacterial hydrogels, photodynamic and photothermal synergistic antibacterial hydrogels, and other synergistic antibacterial hydrogels involving phototherapy.

MXene-based composites in smart wound healing and dressings

MXenes, a class of two-dimensional materials, exhibit considerable potential in wound healing and dressing applications due to their distinctive attributes, including biocompatibility, expansive specific surface area, hydrophilicity, excellent electrical conductivity, unique mechanical properties, facile surface functionalization, and tunable band gaps. These materials serve as a foundation for the development of advanced wound healing materials, offering multifunctional nanoplatforms with theranostic capabilities. Key advantages of MXene-based materials in wound healing and dressings encompass potent antibacterial properties, hemostatic potential, pro-proliferative attributes, photothermal effects, and facilitation of cell growth. So far, different types of MXene-based materials have been introduced with improved features for wound healing and dressing applications. This review covers the recent advancements in MXene-based wound healing and dressings, with a focus on their contributions to tissue regeneration, infection control, anti-inflammation, photothermal effects, and targeted therapeutic delivery. We also discussed the constraints and prospects for the future application of these nanocomposites in the context of wound healing/dressings.

Nanomaterials for Photothermal Antimicrobial Surfaces

Microbial infection diseases are a major threat to human health and have become one of the main causes of mortality. The search for novel antimicrobial strategies is an important challenge for the scientific community, considering also the constant increase of antimicrobial resistance and the rise of new diseases. Among the new strategies to combat microbial infections, the photothermal effect seems to be one of the most promising. Hyperthermia is an effective and broad spectrum strategy for the removal of microbial infections. Among all of the strategies to reduce the diffusion of microbial infections, the preparation of antimicrobial surfaces seems of primary importance. In many cases, in fact, an infection can be diffused through surfaces just by touching them, or by inoculating microbes through an internalizable device, such as an implant, a prosthesis, or a catheter. In this review, we will summarize the recent advances in the preparation of photothermal antibacterial surfaces.

Research Progress on Ti3C2Tx-Based Composite Materials in Antibacterial Field

The integration of two-dimensional Ti3C2Tx nanosheets and other materials offers broader application options in the antibacterial field. Ti3C2Tx-based composites demonstrate synergistic physical, chemical, and photodynamic antibacterial activity. In this review, we aim to explore the potential of Ti3C2Tx-based composites in the fabrication of an antibiotic-free antibacterial agent with a focus on their systematic classification, manufacturing technology, and application potential. We investigate various components of Ti3C2Tx-based composites, such as metals, metal oxides, metal sulfides, organic frameworks, photosensitizers, etc. We also summarize the fabrication techniques used for preparing Ti3C2Tx-based composites, including solution mixing, chemical synthesis, layer-by-layer self-assembly, electrostatic assembly, and three-dimensional (3D) printing. The most recent developments in antibacterial application are also thoroughly discussed, with special attention to the medical, water treatment, food preservation, flexible textile, and industrial sectors. Ultimately, the future directions and opportunities are delineated, underscoring the focus of further research, such as elucidating microscopic mechanisms, achieving a balance between biocompatibility and antibacterial efficiency, and investigating effective, eco-friendly synthesis techniques combined with intelligent technology. A survey of the literature provides a comprehensive overview of the state-of-the-art developments in Ti3C2Tx-based composites and their potential applications in various fields. This comprehensive review covers the variety, preparation methods, and applications of Ti3C2Tx-based composites, drawing upon a total of 171 English-language references. Notably, 155 of these references are from the past five years, indicating significant recent progress and interest in this research area.

MXene-Mediated Catalytic Redox Reactions for Biomedical Applications

Reactive oxygen species (ROS) play a crucial role in orchestrating a myriad of physiological processes within living systems. With the advent of materdicine, an array of nanomaterials has been intricately engineered to influence the redox equilibrium in biological milieus, thereby pioneering a distinctive therapeutic paradigm predicated on ROS-centric biochemistry. Among these, two-dimensional carbides, nitrides, and carbonitrides, collectively known as MXenes, stand out due to their multi-valent and multi-elemental compositions, large surface area, high conductivity, and pronounced local surface plasmon resonance effects, positioning them as prominent contributors in ROS modulation. This review aims to provide an overview of the advancements in harnessing MXenes for catalytic redox reactions in various biological applications, including tumor, anti-infective, and anti-inflammatory therapies. The emphasis lies on elucidating the therapeutic mechanism of MXenes, involving both pro-oxidation and anti-oxidation processes, underscoring the redox-related therapeutic applications facilitated by self-catalysis, photo-excitation, and sono-excitation properties of MXenes. Furthermore, this review highlights the existing challenges and outlines future development trends in leveraging MXenes for ROS-involving disease treatments, marking a significant step towards the integration of these nanomaterials into clinical practice.

Targeting starvation therapy for diabetic bacterial infections with endogenous enzyme-triggered hyaluronan-modified nanozymes in the infection microenvironment

The high-glycemic microenvironment of diabetic wounds promotes bacterial proliferation, leading to persistent infections and delayed wound healing. This poses a significant threat to human health, necessitating the development of new nanodrug visualization platforms. In this study, we designed and synthesized cascade nano-systems modified with targeted peptide and hyaluronic acid for diabetic infection therapy. The nano-systems were able to target the site of infection using LL-37, and in the microenvironment of wound infection, the hyaluronic acid shell of the nano-systems was degraded by endogenous hyaluronidase. This precise degradation released a cascade of nano-enzymes on the surface of the bacteria, effectively destroying their cytoskeleton. Additionally, the metals in the nano-enzymes provided a photo-thermal effect, accelerating wound healing. The cascade nano-visualization platform demonstrated excellent bactericidal efficacy in both in vitro antimicrobial assays and in vivo diabetic infection models. In conclusion, this nano-system employs multiple approaches including targeting, enzyme-catalyzed therapy, photothermal therapy, and chemodynamic therapy to kill bacteria and promote healing. The Ag@Pt-Au-LYZ/HA-LL-37 formulation shows great potential for the treatment of diabetic wounds.

Recent Research on Preparation and Application of Smart Joule Heating Fabrics

Multifunctional wearable heaters have attracted much attention for their effective applications in personal thermal management and medical therapy. Compared to passive heating, Joule heating offers significant advantages in terms of reusability, reliable temperature control, and versatile coupling. Joule-heated fabrics make wearable electronics smarter. This review critically discusses recent advances in Joule-heated smart fabrics, focusing on various fabrication strategies based on material-structure synergy. Specifically, various applicable conductive materials with Joule heating effect are first summarized. Subsequently, different preparation methods for Joule heating fabrics are compared, and then their various applications in smart clothing, healthcare, and visual indication are discussed. Finally, the challenges faced in developing these smart Joule heating fabrics and their possible solutions are discussed.

Organic-inorganic hybrid ZIF-8/MXene/cellulose-based textiles with improved antibacterial and electromagnetic interference shielding performance

Despite the tremendous efforts on developing antibacterial wearable textile materials containing Ti3C2Tx MXene, the singular antimicrobial mechanism, poor antibacterial durability, and oxidation susceptibility of MXene limits their applications. In this context, flexible multifunctional cellulosic textiles were prepared via layer-by-layer assembly of MXene and the in-situ synthesis of zeolitic imidazolate framework-8 (ZIF-8). Specifically, the introduction of highly conductive MXene enhanced the interface interactions between the ZIF-8 layer and cellulose fibers, endowing the green-based materials with outstanding synergistic photothermal/photodynamic therapy (PTT/PDT) activity and adjustable electromagnetic interference (EMI) shielding performance. In-situ polymerization formed a MXene/ZIF-8 bilayer structure, promoting the generation of reactive oxygen species (ROS) while protecting MXene from oxidation. The as-prepared smart textile exhibited excellent bactericidal efficacy of >99.99 % against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) after 5 min of NIR (300 mW cm-2) irradiation which is below the maximum permissible exposure (MPE) limit. The sustained released Zn2+ from the ZIF-8 layer achieved a bactericidal efficiency of over 99.99 % within 48 h without NIR light. Furthermore, this smart textile also demonstrated remarkable EMI shielding efficiency (47.7 dB). Clearly, this study provides an elaborate strategy for designing and constructing multifunctional cellulose-based materials for a variety of applications.

Revolutionizing Infection Control: Harnessing MXene-Based Nanostructures for Versatile Antimicrobial Strategies and Healthcare Advancements

The escalating global health challenge posed by infections prompts the exploration of innovative solutions utilizing MXene-based nanostructures. Societally, the need for effective antimicrobial strategies is crucial for public health, while scientifically, MXenes present promising properties for therapeutic applications, necessitating scalable production and comprehensive characterization techniques. Here we review the versatile physicochemical properties of MXene materials for combatting microbial threats and their various synthesis methods, including etching and top-down or bottom-up techniques. Crucial characterization techniques such as XRD, Raman spectroscopy, SEM/TEM, FTIR, XPS, and BET analysis provide insightful structural and functional attributes. The review highlights MXenes' diverse antimicrobial mechanisms, spanning membrane disruption and oxidative stress induction, demonstrating efficacy against bacterial, viral, and fungal infections. Despite translational hurdles, MXene-based nanostructures offer broad-spectrum antimicrobial potential, with applications in drug delivery and diagnostics, presenting a promising path for advancing infection control in global healthcare.

Supramolecular Assembly Based on Calix(4)arene and Aggregation-Induced Emission Photosensitizer for Phototherapy of Drug-Resistant Bacteria and Skin Flap Transplantation

Photodynamic therapy as a burgeoning and non-invasive theranostic technique has drawn great attention in the field of antibacterial treatment but often encounters undesired phototoxicity of photosensitizers during systemic circulation. Herein, a supramolecular substitution strategy is proposed for phototherapy of drug-resistant bacteria and skin flap repair by using macrocyclic p-sulfonatocalix(4)arene (SC4A) as a host, and two cationic aggregation-induced emission luminogens (AIEgens), namely TPE-QAS and TPE-2QAS, bearing quaternary ammonium group(s) as guests. Through host-guest assembly, the obtained complex exhibits obvious blue fluorescence in the solution due to the restriction of free motion of AIEgens and drastically inhibits efficient type I ROS generation. Then, upon the addition of another guest 4,4'-benzidine dihydrochloride, TPE-QAS can be competitively replaced from the cavity of SC4A to restore its pristine ROS efficiency and photoactivity in aqueous solution. The dissociative TPE-QAS shows a high bacterial binding ability with an efficient treatment for methicillin-resistant Staphylococcus aureus (MRSA) in dark and light irradiation. Meanwhile, it also exhibits an improved survival rate for MRSA-infected skin flap transplantation and largely accelerates the healing process. Thus, such cascaded host-guest assembly is an ideal platform for phototheranostics research.

Dipicolylamine-Zn Induced Targeting and Photo-Eliminating of Pseudomonas aeruginosa and Drug-Resistance Gram-Positive Bacteria

The emergence of drug-resistant bacteria, particularly resistant strains of Gram-negative bacteria, such as Pseudomonas aeruginosa, poses a significant threat to public health. Although antibacterial photodynamic therapy (APDT) is a promising strategy for combating drug-resistant bacteria, actively targeted photosensitizers (PSs) remain unknown. In this study, a PS based on dipicolylamine (DPA), known as WZK-DPA-Zn, is designed for the selective identification of P. aeruginosa and drug-resistant Gram-positive bacteria. WZK-DPA-Zn exploits the synergistic effects of DPA-Zn2+ coordination and cellular uptake, which could effectively anchor P. aeruginosa within a brief period (10 min) without interference from other Gram-negative bacteria. Simultaneously, the cationic nature of WZK-DPA-Zn enhances its interaction with Gram-positive bacteria via electrostatic forces. Compared to traditional clinical antibiotics, WZK-DPA-Zn shows exceptional antibacterial activity without inducing drug resistance. This effectiveness is achieved using the APDT strategy when irradiated with white light or sunlight. The combination of WZK-DPA-Zn with Pluronic-based thermosensitive hydrogel dressings (WZK-DPA-Zn@Gel) effectively eliminates mixed bacterial infections and accelerates wound healing, thereby achieving a synergistic effect where "1+1>2." In summary, this study proposes a precise strategy employing DPA-Zn as the targeting moiety of a PS, facilitating the rapid elimination of P. aeruginosa and drug-resistant Gram-positive bacteria using APDT.

Solar-driven surface-heating membrane distillation using Ti3C2Tx MXene-coated spacers

The emergence of two-dimensional (2D) MXenes as efficient light-to-heat conversion materials offers significant potential for solar-based desalination, particularly in photothermal interfacial evaporation, enabling cost-effective solar-powered membrane distillation (MD). This study investigates solar-powered MD afforded by a photothermally functionalized spacer, which is built by spray-coating Ti3C2Tx MXene sheets on metallic spacers. 2D Ti3C2Tx MXene gives an ultrahigh photothermal conversion efficiency; thereby, by Ti3C2Tx MXene-coated metallic spacer, this rationally designed spacer allows for a localized photothermal conversion and interfacial feed heating effect on the membrane surface, especially for MD operation. As a feed spacer and a photothermal element, Ti3C2Tx MXene-coated metallic spacer exhibited stable enhanced water flux of up to 0.36 kg·m-2h-1 under one sun illumination for a feed salinity of 35 g·L-1, corresponding energy conversion efficiency of 28.3 %. Overall, the developed photothermal Ti3C2Tx MXene-coated spacers displayed great potential in enhancing the performance, scalability, and feasibility of solar-driven MD process, paving the way for further development of photothermal elements that can be implemented in solar MD applications.

Amphiphilic Janus nanoparticles for nitric oxide synergistic photodynamic eradication of MRSA biofilms

Biofilms pose significant threats to public health by causing persistent clinical infections. The development of innovative antibacterial approaches for eliminating biofilms is an urgent necessity. In this study, we developed amphiphilic Janus nanoparticles (JNPs), loaded with hydrophobic chlorin e6 (Ce6) and hydrophilic S-nitrosoglutathione (GSNO), denoted as Ce6-PDA/CaP-GSNO, with the aim to effectively eradicate biofilms and combat methicillin-resistant Staphylococcus aureus (MRSA) infections through nitric oxide (NO) synergistic photodynamic therapy (PDT). Ce6-PDA/CaP-GSNO demonstrated remarkable biofilm penetration ability, efficiently reaching the acidic inner layers, which triggered the rapid release of GSNO, resulting in the generation of an abundant supply of NO. NO not only exhibited potent bactericidal activity but also effectively lowered the GSH level of the biofilm, leading to enhanced efficacy of Ce6. Additionally, the interaction between NO and reactive oxygen species (ROS) resulted in the generation of reactive nitrogen species (RNS), further enhancing PDT efficacy both in vitro and in vivo. In summary, Ce6-PDA/CaP-GSNO demonstrated remarkable biofilm penetration capacity and effective reduction of the GSH level in the biofilms, leading to enhanced PDT efficacy at low photosensitizer doses and laser intensities, thereby minimizing adverse effects on normal tissues. These findings highlight the promising potential of our approach for combating biofilm-related infections.

Sprayable Multifunctional Black Phosphorus Hydrogel with On-Demand Removability for Joint Skin Wound Healing

Wound healing remains a critical challenge in regenerative engineering. Great efforts are devoted to develop functional patches for wound healing. Herein, a novel sprayable black phosphorus (BP)-based multifunctional hydrogel with on-demand removability is presented as a joints' skin wound dressing. The hydrogel is facilely prepared by mixing dopamine-modified oxidized hyaluronic acid, cyanoacetategroup-functionalized dextran containing black phosphorus, and the catalyst histidine. The catechol-containing dopamine can not only enhance tissue adhesiveness, but also endow the hydrogel with antioxidant capacity. In addition, benefiting from the photothermal conversion ability of the BP and thermally reversible performance of the formed C═C double bonds between aldehyde groups and cyanoacetate groups, the resulting hydrogel displays excellent antibacterial performance and on-demand dissolving ability under NIR irradiation. Moreover, by loading vascular endothelial growth factor into the hydrogel, the promoted migration and angiogenesis effects of endothelial cells can also be achieved. Based on these features, it is demonstrated that such sprayable BP hydrogels can effectively facilitate joint wounds healing by accelerating angiogenesis, alleviating inflammation, and improving wound microenvironment. Thus, it is believed that this NIR-responsive removable BP hydrogel dressing will put forward an innovative concept in designing wound dressings.

Highly Aligned Ternary Nanofiber Matrices Loaded with MXene Expedite Regeneration of Volumetric Muscle Loss

Current therapeutic approaches for volumetric muscle loss (VML) face challenges due to limited graft availability and insufficient bioactivities. To overcome these limitations, tissue-engineered scaffolds have emerged as a promising alternative. In this study, we developed aligned ternary nanofibrous matrices comprised of poly(lactide-co-ε-caprolactone) integrated with collagen and Ti3C2Tx MXene nanoparticles (NPs) (PCM matrices), and explored their myogenic potential for skeletal muscle tissue regeneration. The PCM matrices demonstrated favorable physicochemical properties, including structural uniformity, alignment, microporosity, and hydrophilicity. In vitro assays revealed that the PCM matrices promoted cellular behaviors and myogenic differentiation of C2C12 myoblasts. Moreover, in vivo experiments demonstrated enhanced muscle remodeling and recovery in mice treated with PCM matrices following VML injury. Mechanistic insights from next-generation sequencing revealed that MXene NPs facilitated protein and ion availability within PCM matrices, leading to elevated intracellular Ca2+ levels in myoblasts through the activation of inducible nitric oxide synthase (iNOS) and serum/glucocorticoid regulated kinase 1 (SGK1), ultimately promoting myogenic differentiation via the mTOR-AKT pathway. Additionally, upregulated iNOS and increased NO- contributed to myoblast proliferation and fiber fusion, thereby facilitating overall myoblast maturation. These findings underscore the potential of MXene NPs loaded within highly aligned matrices as therapeutic agents to promote skeletal muscle tissue recovery.

In the View of Electrons Transfer and Energy Conversion: The Antimicrobial Activity and Cytotoxicity of Metal-Based Nanomaterials and Their Applications

The global pandemic and excessive use of antibiotics have raised concerns about environmental health, and efforts are being made to develop alternative bactericidal agents for disinfection. Metal-based nanomaterials and their derivatives have emerged as promising candidates for antibacterial agents due to their broad-spectrum antibacterial activity, environmental friendliness, and excellent biocompatibility. However, the reported antibacterial mechanisms of these materials are complex and lack a comprehensive understanding from a coherent perspective. To address this issue, a new perspective is proposed in this review to demonstrate the toxic mechanisms and antibacterial activities of metal-based nanomaterials in terms of energy conversion and electron transfer. First, the antimicrobial mechanisms of different metal-based nanomaterials are discussed, and advanced research progresses are summarized. Then, the biological intelligence applications of these materials, such as biomedical implants, stimuli-responsive electronic devices, and biological monitoring, are concluded based on trappable electrical signals from electron transfer. Finally, current improvement strategies, future challenges, and possible resolutions are outlined to provide new insights into understanding the antimicrobial behaviors of metal-based materials and offer valuable inspiration and instructional suggestions for building future intelligent environmental health.

MXene/Cellulose Composite Cloth for Integrated Functions (if-Cloth) in Personal Heating and Steam Generation

Given the abundant solar light available on our planet, it is promising to develop an advanced fabric capable of simultaneously providing personal thermal management and facilitating clean water production in an energy-efficient manner. In this study, we present the fabrication of a photothermally active, biodegradable composite cloth composed of titanium carbide MXene and cellulose, achieved through an electrospinning method. This composite cloth exhibits favorable attributes, including chemical stability, mechanical performance, structural flexibility, and wettability. Notably, our 0.1-mm-thick composite cloth (RC/MXene IV) raises the temperature of simulated skin by 5.6 °C when compared to a commercially available cotton cloth, which is five times thicker under identical ambient conditions. Remarkably, the composite cloth (RC/MXene V) demonstrates heightened solar light capture efficiency (87.7%) when in a wet state instead of a dry state. Consequently, this cloth functions exceptionally well as a high-performance steam generator, boasting a superior water evaporation rate of 1.34 kg m-2 h-1 under one-sun irradiation (equivalent to 1000 W m-2). Moreover, it maintains its performance excellence in solar desalination processes. The multifunctionality of these cloths opens doors to a diverse array of outdoor applications, including solar-driven water evaporation and personal heating, thereby enriching the scope of integrated functionalities for textiles.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s42765-023-00345-w.

Size-dependent magnetomechanically enhanced photothermal antibacterial effect of Fe3O4@Au/PDA nanodurian

The global health crisis of bacterial resistance to antibiotics requires innovative antibacterial strategies. One promising solution is the exploitation of multifunctional nanoplatforms based on non-resistant antibacterial mechanisms. This work reports a novel Fe3O4@Au/polydopamine (PDA) nanodurian with excellent photothermal-magnetomechanic synergistic antibacterial effects. The one-step formed Au/PDA hybrid shell provides good photothermal properties and spiky surfaces for enhanced magnetomechanic effects. Upon near-infrared (NIR) irradiation, the Fe3O4@Au/PDA nanodurian (200 μg mL-1) achieved nearly 100% antibacterial effect against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The efficiency of photothermal antimicrobial activity was further enhanced by the application of a rotating magnetic field (RMF), with the sterilization efficiency being increased by up to more than a half compared to the action alone. Interestingly, the size of the nanodurian has a significant impact on the synergistic sterilization effect, with larger particles showing a superior performance due to stronger chain-like structures in the magnetic field. Finally, the Fe3O4@Au/PDA nanodurian also demonstrates effective biofilm removal, with larger particles exhibiting the best eradication effect under the photothermal-magnetomechanic treatment. Overall, this magnetic field enhanced photothermal antibacterial strategy provides a promising broad-spectrum antimicrobial solution to combat bacterial infections. Thus, it possesses great potential in future nanomedicine and pollution treatment.

A Stable Open-Shell Conjugated Diradical Polymer with Ultra-High Photothermal Conversion Efficiency for NIR-II Photo-Immunotherapy of Metastatic Tumor

Massive efforts have been concentrated on the advance of eminent near-infrared (NIR) photothermal materials (PTMs) in the NIR-II window (1000-1700 nm), especially organic PTMs because of their intrinsic biological safety compared with inorganic PTMs. However, so far, only a few NIR-II-responsive organic PTMs was explored, and their photothermal conversion efficiencies (PCEs) still remain relatively low. Herein, donor-acceptor conjugated diradical polymers with open-shell characteristics are explored for synergistically photothermal immunotherapy of metastatic tumors in the NIR-II window. By employing side-chain regulation, the conjugated diradical polymer TTB-2 with obvious NIR-II absorption was developed, and its nanoparticles realize a record-breaking PCE of 87.7% upon NIR-II light illustration. In vitro and in vivo experiments demonstrate that TTB-2 nanoparticles show good tumor photoablation with navigation of photoacoustic imaging in the NIR-II window, without any side-effect. Moreover, by combining with PD-1 antibody, the pulmonary metastasis of breast cancer is high-effectively prevented by the efficient photo-immunity effect. Thus, this study explores superior PTMs for cancer metastasis theranostics in the NIR-II window, offering a new horizon in developing radical-characteristic NIR-II photothermal materials.

Nanoarchitecture-based photothermal ablation of cancer: A systematic review

Photothermal therapy (PTT) is an emerging non-invasive method used in cancer treatment. In PTT, near-infrared laser light is absorbed by a chromophore and converted into heat within the tumor tissue. PTT for cancer usually combines a variety of interactive plasmonic nanomaterials with laser irradiation. PTT enjoys PT agents with high conversion efficiency to convert light into heat to destroy malignant tissue. In this review, published studies concerned with the use of nanoparticles (NPs) in PTT were collected by a systematic and comprehensive search of PubMed, Cochrane, Embase, and Scopus databases. Gold, silver and iron NPs were the most frequent choice in PTT. The use of surface modified NPs allowed selective delivery and led to a precise controlled increase in the local temperature. The presence of NPs during PTT can increase the reactive generation of oxygen species, damage the DNA and mitochondria, leading to cancer cell death mainly via apoptosis. Many studies recently used core-shell metal NPs, and the effects of the polymer coating or ligands targeted to specific cellular receptors in order to increase PTT efficiency were often reported. The effective parameters (NP type, size, concentration, coated polymers or attached ligands, exposure conditions, cell line or type, and cell death mechanisms) were investigated individually. With the advances in chemical synthesis technology, NPs with different shapes, sizes, and coatings can be prepared with desirable properties, to achieve multimodal cancer treatment with precision and specificity.

A photoactivatable and phenylboronic acid-functionalized nanoassembly for combating multidrug-resistant gram-negative bacteria and their biofilms

Background

Multidrug-resistant (MDR) gram-negative bacteria-related infectious diseases have caused an increase in the public health burden and mortality. Moreover, the formation of biofilms makes these bacteria difficult to control. Therefore, developing novel interventions to combat MDR gram-negative bacteria and their biofilms-related infections are urgently needed. The purpose of this study was to develop a multifunctional nanoassembly (IRNB) based on IR-780 and N, N'-di-sec-butyl-N, N'- dinitroso-1,4-phenylenediamine (BNN6) for synergistic effect on the infected wounds and subcutaneous abscesses caused by gram-negative bacteria.

Methods

The characterization and bacteria-targeting ability of IRNB were investigated. The bactericidal efficacy of IRNB against gram-negative bacteria and their biofilms was demonstrated by crystal violet staining assay, plate counting method and live/dead staining in vitro. The antibacterial efficiency of IRNB was examined on a subcutaneous abscess and cutaneous infected wound model in vivo. A cell counting kit-8 assay, Calcein/PI cytotoxicity assay, hemolysis assay and intravenous injection assay were performed to detect the biocompatibility of IRNB in vitro and in vivo.

Results

Herein, we successfully developed a multifunctional nanoassembly IRNB based on IR-780 and BNN6 for synergistic photothermal therapy (PTT), photodynamic therapy (PDT) and nitric oxide (NO) effect triggered by an 808 nm laser. This nanoassembly could accumulate specifically at the infected sites of MDR gram-negative bacteria and their biofilms via the covalent coupling effect. Upon irradiation with an 808 nm laser, IRNB was activated and produced both reactive oxygen species (ROS) and hyperthermia. The local hyperthermia could induce NO generation, which further reacted with ROS to generate ONOO-, leading to the enhancement of bactericidal efficacy. Furthermore, NO and ONOO- could disrupt the cell membrane, which converts bacteria to an extremely susceptible state and further enhances the photothermal effect. In this study, IRNB showed a superior photothermal-photodynamic-chemo (NO) synergistic therapeutic effect on the infected wounds and subcutaneous abscesses caused by gram-negative bacteria. This resulted in effective control of associated infections, relief of inflammation, promotion of re-epithelization and collagen deposition, and regulation of angiogenesis during wound healing. Moreover, IRNB exhibited excellent biocompatibility, both in vitro and in vivo.

Conclusions

The present research suggests that IRNB can be considered a promising alternative for treating infections caused by MDR gram-negative bacteria and their biofilms.

Ag+-Adsorbing Semiconducting Polymer Nanosponge for Smart Local Treatment of Wound Infection

Nanoplatform combined with photothermal therapy (PTT) and silver nanoparticles have been widely used to combat bacterial infections. However, the development of environmentally benign antibacterial nanoplatforms with controllable and long-term antibacterial activity is still challenging. Herein, we synthesized an Ag+-adsorbing organic semiconducting polymeric nanosponge (PDPP3T NPe@Ag+) to realize Ag+ enhanced photothermal anti-infective therapy. Furthermore, the PDPP3T NPe@Ag+ sponge can also spatiotemporally release silver ions in a pH/NIR light-responsive manner for controllable and long-term antimicrobial therapy. Owing to good biocompatibility and controlled release of silver ions, PDPP3T NPe@Ag+ can effectively kill bacteria in vitro and promote wound healing in vivo. We expect that this antimicrobial platform could be utilized as a robust antibacterial agent for infective therapy.

Upscaled Synthesis Protocol for Phase-Pure, Colloidally Stable MXenes with Long Shelf Lives

MXenes are electrically conductive 2D transition metal carbides/nitrides obtained by the etching of nanolaminated MAX phase compounds, followed by exfoliation to single- or few-layered nanosheets. The mainstream chemical etching processes have evolved from pure hydrofluoric acid (HF) etching into the innovative "minimally intensive layer delamination" (MILD) route. Despite their current popularity and remarkable application potential, the scalability of MILD-produced MXenes remains unproven, excluding MXenes from industrial applications. This work proposes a "next-generation MILD" (NGMILD) synthesis protocol for phase-pure, colloidally stable MXenes that withstand long periods of dry storage. NGMILD incorporates the synergistic effects of a secondary salt, a richer lithium (Li) environment, and iterative alcohol-based washing to achieve high-purity MXenes, while improving etching efficiency, intercalation, and shelf life. Moreover, NGMILD comprises a sulfuric acid (H2 SO4 ) post-treatment for the selective removal of the Li3 AlF6 impurity that commonly persists in MILD-produced MXenes. This work demonstrates the upscaled NGMILD synthesis of (50 g) phase-pure Ti3 C2 Tz MXene clays with high extraction yields (>22%) of supernatant dispersions. Finally, NGMILD-produced MXene clays dry-stored for six months under ambient conditions experience minimal degradation, while retaining excellent redispersibility. Overall, the NGMILD protocol is a leap forward toward the industrial production of MXenes and their subsequent market deployment.

Interfacial and Defect Polarization Enhanced Microwave Noninvasive Therapy for Staphylococcus aureus-Infected Chronic Osteomyelitis

Chronic osteomyelitis (COM), is a long-term, constant, and intractable disease mostly induced by infection from the invasion of Staphylococcus aureus (S. aureus) into bone cells. Here, we describe a highly effective microwave (MW) therapeutic strategy for S. aureus-induced COM based on the in situ growth of interfacial oxygen vacancy-rich molybdenum disulfide (MoS2)/titanium carbide (Ti3C2Tx) MXene with oxygen-deficient titanium dioxide (TiO2-x) on Ti3C2Tx (labeled as HU-MoS2/Ti3C2Tx) by producing reactive oxygen species (ROS) and heat. HU-MoS2/Ti3C2Tx produced heat and ROS, which could effectively treat S. aureus-induced COM under MW irradiation. The underlying mechanism determined by density functional theory (DFT) and MW vector network analysis was that HU-MoS2/Ti3C2Tx formed a high-energy local electric field under MW irradiation, consequently generating more high-energy free electrons to pass and move across the interface at a high speed and accelerate by the heterointerface, which enhanced the charge accumulation on both sides of the interface. Moreover, these charges were captured by the oxygen species adsorbed at the HU-MoS2/Ti3C2Tx interface to produce ROS. MoS2 facilitated multiple reflections and scattering of electromagnetic waves as well as enhanced impedance matching. Ti3C2Tx enhanced the conduction loss of electromagnetic waves, while functional groups induced dipole polarization to enhance attenuation of MW.

Fluoride-activated photothermal system for promoting bacteria-infected wound healing

Although photothermal therapy (PTT) employing nanozymes has shown excellent antibacterial potential, excessive heating generally harms host cells and hinders recovery. Herein, we report an innovative technique for acquiring the programmed temperature by managing the catalytic activity of nanozymes. The photothermal system of CeO2 + F- + TMB can obtain precise photothermal temperature by adjusting the concentration of fluoride ions under near-infrared irradiation. At the optimized photothermal temperature, the photothermal system affords fine photothermal antibacterial treatment with high-efficiency antibacterial effects against Staphylococcus aureus and Escherichia coli in vitro. In vivo wound healing experiments confirm that the system can effectively promote fibroblast proliferation, angiogenesis and collagen deposition with remarkable wound healing efficiency. This strategy offers a novel design concept for creating a new generation of PTT and opens the way for the creation of alternative antibiotics.

Synthesis of dendritic cobalt with flower-like structure by a facile wet chemistry method as an excellent electromagnetic wave absorber

In this study, a three-dimensional (3D) floral dendritic cobalt (FDC) consisting of layered flakes was effectively synthesized using a facile wet chemistry method. The impact of the molar amount of NaOH on the microscopic morphology, magnetic characteristics, and electromagnetic wave (EMW) absorption properties of the FDC magnetic materials was comprehensively investigated. The results revealed that the prepared FDC features primary, secondary, and multi-level branches, with the majority of secondary branches being parallel to one another. The dendrites grew closely towards the flower's center at one end, while the tips extend in various directions, forming a dendritic flower cluster. The optimal reflection loss (RL) of S3 at 9.3 GHz was -56.34 dB with a thickness of 1.89 mm, and the maximum effective absorption bandwidth (EAB, RL < -10 dB) reached 6.0 GHz (12.0-18.0 GHz) at a thickness of 1.30 mm. Consequently, the FDC magnetic materials produced in this study presented a method for fabricating high-performance electromagnetic wave absorption (EMWA) materials.

Trends in Photothermal Nanostructures for Antimicrobial Applications

The rapid development of antimicrobial resistance due to broad antibiotic utilisation in the healthcare and food industries and the non-availability of novel antibiotics represents one of the most critical public health issues worldwide. Current advances in nanotechnology allow new materials to address drug-resistant bacterial infections in specific, focused, and biologically safe ways. The unique physicochemical properties, biocompatibility, and wide range of adaptability of nanomaterials that exhibit photothermal capability can be employed to develop the next generation of photothermally induced controllable hyperthermia as antibacterial nanoplatforms. Here, we review the current state of the art in different functional classes of photothermal antibacterial nanomaterials and strategies to optimise antimicrobial efficiency. The recent achievements and trends in developing photothermally active nanostructures, including plasmonic metals, semiconductors, and carbon-based and organic photothermal polymers, and antibacterial mechanisms of action, including anti-multidrug-resistant bacteria and biofilm removal, will be discussed. Insights into the mechanisms of the photothermal effect and various factors influencing photothermal antimicrobial performance, emphasising the structure-performance relationship, are discussed. We will examine the photothermal agents' functionalisation for specific bacteria, the effects of the near-infrared light irradiation spectrum, and active photothermal materials for multimodal synergistic-based therapies to minimise side effects and maintain low costs. The most relevant applications are presented, such as antibiofilm formation, biofilm penetration or ablation, and nanomaterial-based infected wound therapy. Practical antibacterial applications employing photothermal antimicrobial agents, alone or in synergistic combination with other nanomaterials, are considered. Existing challenges and limitations in photothermal antimicrobial therapy and future perspectives are presented from the structural, functional, safety, and clinical potential points of view.

Mild Photothermal-Stimulation Based on Injectable and Photocurable Hydrogels Orchestrates Immunomodulation and Osteogenesis for High-Performance Bone Regeneration

A photoactivated bone scaffold integrated with minimally invasive implantation and mild thermal-stimulation capability shows great promise in the repair and regeneration of irregularly damaged bone tissues. Developing multifunctional photothermal biomaterials that can simultaneously serve as both controllable thermal stimulators and biodegradable engineering scaffolds for integrated immunomodulation, infection therapy, and impaired bone repair remains an enormous challenge. Herein, an injectable and photocurable hydrogel therapeutic platform (AMAD/MP) based on alginate methacrylate, alginate-graft-dopamine, and polydopamine (PDA)-functionalized Ti3C2 MXene (MXene@PDA) nanosheets is rationally designed for near-infrared (NIR)-mediated bone regeneration synergistic immunomodulation, osteogenesis, and bacterial elimination. The optimized AMAD/MP hydrogel exhibits favorable biocompatibility, osteogenic activity, and immunomodulatory functions in vitro. The proper immune microenvironment provided by AMAD/MP could further modulate the balance of M1/M2 phenotypes of macrophages, thereby suppressing reactive oxygen species-induced inflammatory status. Significantly, this multifunctional hydrogel platform with mild thermal stimulation efficiently attenuates local immune reactions and further promotes new bone formation without the addition of exogenous cells, cytokines, or growth factors. This work highlights the potential application of an advanced multifunctional hydrogel providing photoactivated on-demand thermal cues for bone tissue engineering and regenerative medicine.

Sunlight propelled two-dimensional nanorobots with enhanced mechanical damage of bacterial membrane

Bacterial pollution in water sources poses a serious threat to human health and causes a water crisis. To treat it efficiently and ecologically, many studies have explored the antibacterial properties of two-dimensional nanomaterials in water, but their static antibacterial modes limit their effectiveness. In this work, we designed a facile and effective antibacterial nanorobots by loading super small gold nanorods (sAuNR) onto the surface of MXene nanosheets (MXene@sAuNR). The plasmon resonance effect of sAuNR can enhance the optical absorption cross section of the nanorobots, thereby improving their motion ability under irradiation and then causing cell membrane mechanical damage to bacteria. Our research proved that nanorobots with good optical driving characteristics displayed gratifying antibacterial properties even at ultra-low concentration as 5 µg/mL within 30 min. Furthermore, the nanorobots showed satisfactory antibacterial efficiency in real river samples under sunlight irradiation. These nanorobots presented in this study provides valuable insights towards designing self-energy collection and self-driving antibacterial materials that overcome the shortcomings of conventional static antibacterial methods. As sunlight is the cheapest and natural light source, these nanorobots have opened an effective and sustainable way for large-scale treatment of bacterial pollution in water.

Molecularly imprinted polymers (MIPs): emerging biomaterials for cancer theragnostic applications

Cancer is a disease caused by abnormal cell growth that spreads through other parts of the body and threatens life by destroying healthy tissues. Therefore, numerous techniques have been employed not only to diagnose and monitor the progress of cancer in a precise manner but also to develop appropriate therapeutic agents with enhanced efficacy and safety profiles. In this regard, molecularly imprinted polymers (MIPs), synthetic receptors that recognize targeted molecules with high affinity and selectivity, have been intensively investigated as one of the most attractive biomaterials for theragnostic approaches. This review describes diverse synthesis strategies to provide the rationale behind these synthetic antibodies and provides a selective overview of the recent progress in the in vitro and in vivo targeting of cancer biomarkers for diagnosis and therapeutic applications. Taken together, the topics discussed in this review provide concise guidelines for the development of novel MIP-based systems to diagnose cancer more precisely and promote successful treatment. Molecularly imprinted polymers (MIPs), synthetic receptors that recognize targeted molecules with high affinity and selectivity, have been intensively investigated as one of the most attractive biomaterials for cancer theragnostic approaches. This review describes diverse synthesis strategies to provide the rationale behind these synthetic antibodies and provides a selective overview of the recent progress in the in vitro and in vivo targeting of cancer biomarkers for diagnosis and therapeutic applications. The topics discussed in this review aim to provide concise guidelines for the development of novel MIP-based systems to diagnose cancer more precisely and promote successful treatment.

MXene nanomaterials in biomedicine: A bibliometric perspective

Purpose: MXene is two-dimensional (2D) nanomaterials that comprise transition metal carbides, nitrides, and carbonitrides. Their unique nanostructure attributes it a special role in medical applications. However, bibliometric studies have not been conducted in this field. Therefore, the aim of the present study was to conduct a bibliometric analysis to evaluate the global scientific output of MXene in biomedical research, explore the current situation of this field in the past years and predicte its research hotpots. Methods: We utilized visual analysis softwares Citespace and Bibliometrix to analyze all relevant documents published in the period of 2011-2022. The bibliometric records were obtained from the Web of Science Core Collection. Results: A total of 1,489 publications were analyzed in this study. We observed that China is the country with the largest number of publications, with Sichuan University being the institution with the highest number of publications in this field. The most publications on MXene medicine research in the past year were found primarily in journals about Chemistry/Materials/Physics. Moreover, ACS Applied Materials and Interfaces was found to be the most productive journal in this field. Co-cited references and keyword cluster analysis revealed that #antibacterial# and #photothermal therapy# are the research focus keyword and burst detection suggested that driven wearable electronics were newly-emergent research hot spots. Conclusion: Our bibliometric analysis indicates that research on MXene medical application remains an active field of study. At present, the research focus is on the application of MXene in the field of antibacterial taking advantage of its photothermal properties. In the future, wearable electronics is the research direction of MXene medical application.