Engineering Gold Nanorod-Copper Sulfide Heterostructures with Enhanced Photothermal Conversion Efficiency and Photostability

Leveraging Non-Radiative Transitions in Asphaltenes-Derived Carbon Dots for Cancer Photothermal Therapy

Cancer photothermal therapy leverages the capability of photothermal agents to convert light to heat for cancer cell ablation and necrosis. However, most conventional photothermal agents (Au, CuS, Pd, mesoporous silica nanoparticles, and indocyanine green dye) either face scalability challenges or photobleached upon prolonged irradiation which jeopardizes practical applications. Here, asphaltenes-derived carbon dots (ACDs, 5 nm) are rationally engineered as a low-cost and photostable photothermal agent with negligible in vivo cytotoxicity. The abundant water-solvating functional groups on the ACDs surface endows them with excellent water re-dispersibility that outperforms those of most commercial nanomaterials. Photothermal therapeutic property of the ACDs is mechanistically described by non-radiative transitions of excited electrons at 808 nm via internal conversions and vibrational relaxations. Consequently, the ACDs offer cancer photothermal therapy in mice within 15 days post-exposure to one-time near infrared irradiation. This pioneering study showcases the first utilization of asphaltenes-based materials for cancer therapy and is expected to arouse further utilization of such materials in various cancer theranostics.

Construction of polypyrrole nanoparticles with a rough surface for enhanced chemo-photothermal therapy against triple negative breast cancer

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer, characterized by aggressive malignancy and a poor prognosis. Emerging nanomedicine-based combination therapy represents one of the most promising strategies for combating TNBC. Polypyrrole nanoparticles (PPY) are excellent drug delivery vehicles with outstanding photothermal performances. However, the impact of morphology on PPY's drug loading efficiency and photothermal properties remains largely unexplored. In this study, we propose that pluronic P123 can assist in the synthesis of polypyrrole nanoparticles with rough surfaces (rPPY). During the synthesis, P123 formed small micelles around the nanoparticle surface, which were later removed, resulting in small pits and cavities in rPPY. Subsequently, the rPPY was loaded with the chemotherapy drug gemcitabine (Gem@rPPY) for chemo-photothermal therapy against TNBCs. Our results demonstrate that rPPY exhibited superior photothermal performance and significantly enhanced drug loading efficiency by five times compared to smooth PPY nanoparticles. In vitro assessments confirmed Gem@rPPY's robust photothermal properties by efficiently converting light into heat. Cell culture experiments with 4T1 cells and a TNBC mice model revealed significant tumor suppression upon Gem@rPPY administration, emphasizing its efficacy in inducing apoptosis. Toxicity evaluations demonstrated minimal adverse effects both in vitro and in vivo, highlighting the biocompatibility of Gem@rPPY. Overall, this study introduces a promising combination therapy nanoplatform that underscores the importance of surface engineering to enhance therapeutic outcomes and overcome current limitations in TNBC therapy.

Development of pH-responsive porphyran-coated gold nanorods for tumor photothermal and immunotherapy

Cancer poses a significant threat to human health, and monotherapy frequently fails to achieve optimal therapeutic outcomes. Based on this premise, porphyran (PHP), a marine polysaccharide with immunomodulatory function, was used as a framework to coat gold nanorods and construct a novel nanomedicine (PHP-MPBA-GNRs) combining photothermal therapy and immunotherapy. In this design, PHP not only maintained the dispersion stability and photothermal stability of gold nanorods but also could be released under weakly acidic conditions to activate anti-tumor immunity. In vivo studies have shown that PHP-MPBA-GNRs can effectively inhibit tumor cell proliferation and reduce metastasis under near-infrared (NIR) light irradiation. Preliminary mechanistic investigations revealed that PHP-MPBA-GNRs could increase reactive oxygen species (ROS) and induce apoptosis in cancer cells. The PHP in PHP-MPBA-GNRs can also activate dendritic cells and up-regulate the expression of co-stimulatory molecules and antigen-presenting complexes. All biological experiments, including in vivo tests, demonstrated that PHP-MPBA-GNRs achieved a combination of photothermal therapy and immunotherapy for tumors.

An ultrasensitive electrochemical immunosensor based on meso-PdN NCs and Au NPs/N-CNTs for quantitative cTnI detection

Electrochemical immunosensors have gained considerable attention in detecting human disease markers due to their excellent specificity, high sensitivity, and facile operation. Herein, a rational-designed sandwich-type electrochemical immunosensor is constructed for the sensitive detection of cardiac troponin I (cTnI) using nitrogen-doped carbon nanotubes loaded with gold nanoparticles (Au NPs/N-CNTs) as substrate and highly active mesoporous palladium-nitrogen nanocubes (meso-PdN NCs) as secondary antibody markers. Benefitting from its large specific surface area (638.04 m2 g-1) and high nitrogen content, novel polydopamine (PDA)/ halloysite nanotubes (HNTs) hybrid derived one-dimensional (1D) N-CNTs can provide more binding sites for the in-situ growth of Au NPs to connect Ab1. Furthermore, as an ideal substrate material, Au NPs/N-CNTs exhibit finely tuned mesoporous structures and outstanding conductivity, which facilitate the mass and electron transfer during the electrocatalysis process. Besides, highly concave surfaces and crystalline mesopores of meso-PdN NCs expose more surfaces and crevices, providing abundant reactive sites for H2O2 reduction. Remarkably, the as-obtained immunosensor presented a wide linear range (from 10 fg mL-1 to 100 ng mL-1) and an excellent low detection limit (9.85 fg mL-1). This study may offer new insights into the precise fabrication of efficient electrochemical immunosensors for various clinical diagnosis applications.

Dual-plasmonic CuS@Au heterojunctions synergistic enhanced photothermal and colorimetric dual signal for sensitive multiplexed LFIA

Multiplexed immunodetection, which achieves qualitative and quantitative outcomes for multiple targets in a single-run process, provides more sufficient results to guarantee food safety. Especially, lateral flow immunoassay (LFIA), with the ability to offer multiple test lines for analytes and one control line for verification, is a forceful candidate in multiplexed immunodetection. Nevertheless, given that single-signal mode is incredibly vulnerable to interference, further efforts should be engrossed on the combination of multiplexed immunodetection and multiple signals. Photothermal signal has sparked significant excitement in designing immunosensors. In this work, by optimizing and comparing the amount of gold, CuS@Au heterojunctions (CuS@Au HJ) were synthesized. The dual-plasmonic metal-semiconductor hybrid heterojunction exhibits a synergistic photothermal performance by increasing light absorption and encouraging interfacial electron transfer. Meanwhile, the colorimetric property is synergistic enhanced, which is conducive to reduce the consumption of antibodies and then improve assay sensitivity. Therefore, CuS@Au HJ are suitable to be constructed in a dual signal and multiplexed LFIA (DSM-LFIA). T-2 toxin and deoxynivalenol (DON) were used as model targets for the simulated multiplex immunoassay. In contrast to colloidal gold-based immunoassay, the built-in sensor has increased sensitivity by ≈ 4.42 times (colorimetric mode) and ≈17.79 times (photothermal mode) for DON detection and by ≈ 1.75 times (colorimetric mode) and ≈13.09 times (photothermal mode) for T-2 detection. As a proof-of-concept application, this work provides a reference to the design of DSM-LFIA for food safety detection.

Synthesis of Structure-Adjustable R-Au/Pt-CdS Nanohybrids with Strong Plasmon Coupling and Improved Photothermal Conversion Performance

Noble metal nanomaterials with a localized surface plasmon resonance effect exhibit outstanding advantages in areas such as photothermal therapy and photocatalysis. As a unique plasmonic metal nanostructure, gold nanobipyramids have been attracting much interest due to their strong specific local electric field intensity, large optical cross sections, and high refractive index sensitivity. In this study, we propose a novel three-component hetero-nanostructure composed of rough gold nanobipyramids (R-Au NBPs), Pt, and CdS. Initially, purified gold nanobipyramids are regrown to form R-Au NBPs that have a certain degree of roughness. These R-Au NBP substrates with a rough surface provide more hotspots and strengthen the intensity of localized electric fields. Subsequently, Pt and CdS nanoparticles are selectively deposited onto the surface of R-Au NBPs. Pt nanoparticles can provide more active sites. Each component of this hetero-nanostructure directly contacts others, creating multiple electron transfer channels. This novel design allows for tunable localized plasmon resonance wavelengths ranging from the visible to near-infrared regions. These factors contribute to the final superior photothermal conversion performance of the R-Au/Pt-CdS nanohybrids. Under the irradiation of near-infrared light (1064 nm), the photothermal conversion efficiency of R-Au/Pt-CdS reached 38.88%, which is 4.49, 1.5, and 1.22 times higher than that of Au NBPs, R-Au NBPs, and R-Au NBPs/Pt, respectively.

Near-infrared responsive gold nanorods for highly sensitive colorimetric and photothermal lateral flow immuno-detection of SARS-CoV-2

The highly infectious characteristics of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), highlight the necessity of sensitive and rapid nucleocapsid (N) protein-based antigen testing for early triage and epidemic management. In this study, a colorimetric and photothermal dual-mode lateral flow immunoassay (LFIA) platform for the rapid and sensitive detection of the SARS-CoV-2 N protein was developed based on gold nanorods (GNRs), which possessed tunable local surface plasma resonance (LSPR) absorption peaks from UV-visible to near-infrared (NIR). The LSPR peak was adjusted to match the NIR emission laser 808 nm by controlling the length-to-diameter ratio, which could maximize the photothermal conversion efficiency and achieve photothermal detection signal amplification. Qualitative detection of SARS-CoV-2 N protein was achieved by observing the strip color, and the limit of detection was 2 ng mL-1, while that for photothermal detection was 0.096 ng mL-1. Artificial saliva samples spiked with the N protein were analyzed with the recoveries ranging from 84.38% to 107.72%. The intra-assay and inter-assay coefficients of variation were 6.76% and 10.39%, respectively. We further evaluated the reliability of this platform by detecting 40 clinical samples collected from nasal swabs, and the results matched well with that of nucleic acid detection (87.5%). This method shows great promise in early disease diagnosis and screening.

Engineering of copper sulfide mediated by phototherapy performance

Copper sulfide based phototherapy, including photothermal therapy and photodynamic therapy, is an emerging minimally invasive treatment of tumor, which the light was converted to heat or reactive oxygen to kill the tumor cells. Compared with conventional chemotherapy and radiation therapy, Cu2-x S based phototherapy is more efficient and has fewer side effects. However, considering the dose-dependent toxicity of Cu2-x S, the performance of Cu2-x S based phototherapy still cannot meet the requirement of the clinical application to now. To overcome this limitation, engineering of Cu2-x S to improve the phototherapy performance by increasing light absorption has attracted extensive attention. For better guidance of Cu2-x S engineering, we outline the currently engineering method being explored, including (1) structural engineering, (2) compositional engineering, (3) functional engineering, and (4) performance engineering. Also, the relationship between the engineering method and phototherapy performance was discussed in this review. In addition, the further development of Cu2-x S based phototherapy is prospected, including smart materials based phototherapy, phototherapy induced immune microenvironment modulation et al. This review will provide new ideas and opportunities for engineering of Cu2-x S with better phototherapy performance. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Electrochemically Triggered Self-Adaptive Reconstruction of an all-Purpose Electrode for Photothermally Enhanced Capacitors

Large-capacity energy storage devices are attracting widespread research attention. However, the decreased capacity of these devices due to cold weather is a huge obstacle for their practical use. In this study, an electrochemical self-adaptive reconstructed Cux S/Cu(OH)2 -based symmetric energy storage device is proposed. This device provides a satisfactorily enhanced photothermal capacity under solar irradiation. After electrochemical reconstruction treatment, the morphological structure is rearranged and the Cux S component is partially converted to electrochemically active Cu(OH)2 with the introduction of a large number of active sites. The resulting Cux S/Cu(OH)2 electrode provides a significant capacitance of 115.2 F cm-2 at 5 mA cm-2 . More importantly, its wide working potential range and superior photo-to-thermal conversion ability endow Cux S/Cu(OH)2 with superb performance as full-purpose photothermally enhanced capacitance electrodes. Under solar irradiation, the surface temperature of Cux S/Cu(OH)2 is elevated by 76.6 °C in only 30 s, and the capacitance is boosted to 230.4% of the original capacitance at a low temperature. Furthermore, the assembled symmetric energy storage device also delivers a photothermal capacitance enhancement of 200.3% under 15 min solar irradiation.

Enhanced photothermal therapy performance of D-A conjugated polymers based on [1,2,3]triazolo[4,5-g]quinoxaline by manipulating molecular motion

Donor-acceptor (D-A) conjugated polymers can favor the nonradiative thermal dissipation process, due to the formation of an intramolecular charge transfer (ICT) state resulting from the electron cloud delocalization of the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital). Thus, to realize a high extinction coefficient and excellent photothermal conversion ability for a single photothermal agent, donor-acceptor type conjugated polymers PBDT-QTz and PCDT-QTz, comprising a new electron-deficient unit 2-(2-decyltetradecyl)-6,7-dimethyl-2H-[1,2,3]triazolo [4,5-g] quinoxaline (QTz) as the acceptor and 4,8-di(thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene (BDT) or 4H-cyclopenta[2,1-b:3,4-b'] dithiophene (CDT) as the donor, are designed and synthesized by manipulating intramolecular motion. The high extinction coefficient of 28.5 L g-1 cm-1 at 850 nm and the optimal photothermal conversion efficiency of 64.3% under an 808 nm laser are achieved based on PBDT-QTz. Consequently, PBDT-QTz nanoparticles can be successfully used for both in vitro and in vivo experiments. After intravenous administration and 808 nm laser irradiation, HeLa tumor-bearing mice achieve complete tumor remission without recurrence. The results provide an efficient photothermal agent by manipulating molecular motion.

Photothermal Effect of Gold Nanoparticles as a Nanomedicine for Diagnosis and Therapeutics

Gold nanoparticles (AuNPs) have received great attention for various medical applications due to their unique physicochemical properties. AuNPs with tunable optical properties in the visible and near-infrared regions have been utilized in a variety of applications such as in vitro diagnostics, in vivo imaging, and therapeutics. Among the applications, this review will pay more attention to recent developments in diagnostic and therapeutic applications based on the photothermal (PT) effect of AuNPs. In particular, the PT effect of AuNPs has played an important role in medical applications utilizing light, such as photoacoustic imaging, photon polymerase chain reaction (PCR), and hyperthermia therapy. First, we discuss the fundamentals of the optical properties in detail to understand the background of the PT effect of AuNPs. For diagnostic applications, the ability of AuNPs to efficiently convert absorbed light energy into heat to generate enhanced acoustic waves can lead to significant enhancements in photoacoustic signal intensity. Integration of the PT effect of AuNPs with PCR may open new opportunities for technological innovation called photonic PCR, where light is used to enable fast and accurate temperature cycling for DNA amplification. Additionally, beyond the existing thermotherapy of AuNPs, the PT effect of AuNPs can be further applied to cancer immunotherapy. Controlled PT damage to cancer cells triggers an immune response, which is useful for obtaining better outcomes in combination with immune checkpoint inhibitors or vaccines. Therefore, this review examines applications to nanomedicine based on the PT effect among the unique optical properties of AuNPs, understands the basic principles, the advantages and disadvantages of each technology, and understands the importance of a multidisciplinary approach. Based on this, it is expected that it will help understand the current status and development direction of new nanoparticle-based disease diagnosis methods and treatment methods, and we hope that it will inspire the development of new innovative technologies.

Biomimetic Gold Nanorods Modified with Erythrocyte Membranes for Imaging-Guided Photothermal/Gene Synergistic Therapy

Pancreatic cancer (PC) is one of the most malignant cancers that develops rapidly and carries a poor prognosis. Synergistic cancer therapy strategy could enhance the clinical efficacy compared to either treatment alone. In this study, gold nanorods (AuNRs) were used as siRNA delivery vehicles to interfere with the oncogenes of KRAS. In addition, AuNRs were one of anisotropic nanomaterials that can absorb near-infrared (NIR) laser and achieve rapid photothermal therapy for malignant cancer cells. Modification of the erythrocyte membrane and antibody Plectin-1 occurred on the surface of the AuNRs, making them a promising target nanocarrier for enhancing antitumor effects. As a result, biomimetic nanoprobes presented advantages in biocompatibility, targeting capability, and drug-loading efficiency. Moreover, excellent antitumor effects have been achieved by synergistic photothermal/gene treatment. Therefore, our study would provide a general strategy to construct a multifunctional biomimetic theranostic multifunctional nanoplatform for preclinical studies of PC.

Understanding Metal-Semiconductor Plasmonic Resonance Coupling through Surface-Enhanced Raman Scattering

Although there has been intense research on plasmon-induced charge transfer within metal/semiconductor heterostructures, previous studies have all focused on the surface plasmonic resonance (SPR) of only noble metals. Herein and for the first time, we observe and take into account the plasmonic coupling between SPR of both noble-metal and semiconductor nanostructures. A W₁₈O₄₉/Ag heterostructure composed of metallic Ag nanoparticles (Ag NPs) and semiconducting W₁₈O₄₉ nanowires (W₁₈O₄₉ NWs) is designed and fabricated, which exhibits a broad and strong SPR absorption in the visible wavelength range. This SPR band is attributed to the SPR coupling between the SPR of both Ag NPs and W₁₈O₄₉ NWs. Surface-enhanced Raman scattering (SERS) is then used to reveal the interactions between the metal SPR, semiconductor SPR, and the heterostructure's charge transfer (CT) process, demonstrating that such coupled SPR enhanced the heterostructure's internal CT and SERS signals. Finally, we proposed a new coupled-plasmon-induced charge transfer mechanism to interpret the improved CT efficiency between the SERS substrate and molecules. Our work provides insight for further studies on plasmonic effects and interfacial charge transfer in metal/semiconductor heterostructures.

IR780-doped cobalt ferrite nanoparticles@poly(ethylene glycol) microgels as dual-enzyme immobilized micro-systems: Preparations, photothermal-responsive dual-enzyme release, and highly efficient recycling

To solve the problems of separating dual enzymes from the carriers of dual-enzyme immobilized micro-systems and greatly increase the carriers' recycling times, photothermal-responsive micro-systems of IR780-doped cobalt ferrite nanoparticles@poly(ethylene glycol) microgels (CFNPs-IR780@MGs) are prepared. A novel two-step recycling strategy is proposed based on the CFNPs-IR780@MGs. First, the dual enzymes and the carriers are separated from the reaction system as a whole via magnetic separation. Second, the dual enzymes and the carriers are separated through photothermal-responsive dual-enzyme release so that the carriers can be reused. Results show that CFNPs-IR780@MGs is 281.4 ± 9.6 nm with a shell of 58.2 nm, and the low critical solution temperature is 42 °C, and the photothermal conversion efficiency increases from 14.04% to 58.41% by doping 1.6% of IR780 into the CFNPs-IR780 clusters. The dual-enzyme immobilized micro-systems and the carriers are recycled 12 and 72 times, respectively, and the enzyme activity remains above 70%. The micro-systems can realize whole recycling of the dual enzymes and carriers and further recycling of the carriers, thus providing a simple and convenient recycling method for dual-enzyme immobilized micro-systems. The findings reveal the micro-systems' important application potential in biological detection and industrial production.

Nanotechnology-enabled immunogenic cell death for improved cancer immunotherapy

Tumor immunotherapy has revolutionized the field of oncology treatments in recent years. As one of the promising strategies of cancer immunotherapy, tumor immunogenic cell death (ICD) has shown significant potential for tumor therapy. Nanoparticles are widely used for drug delivery due to their versatile characteristics, such as stability, slow blood elimination, and tumor-targeting ability. To increase the specificity of ICD inducers and improve the efficiency of ICD induction, functionally specific nanoparticles, such as liposomes, nanostructured lipid carriers, micelles, nanodiscs, biomembrane-coated nanoparticles and inorganic nanoparticles have been widely reported as the vehicles to deliver ICD inducers in vivo. In this review, we summarized the strategies of different nanoparticles for ICD-induced cancer immunotherapy, and systematically discussed their advantages and disadvantages as well as provided feasible strategies for solving these problems. We believe that this review will offer some insights into the design of effective nanoparticulate systems for the therapeutic delivery of ICD inducers, thus, promoting the development of ICD-mediated cancer immunotherapy.

A robust Au@Cu2-xS nanoreactor assembled by silk fibroin for enhanced intratumoral glucose depletion and redox dyshomeostasis

Intracellular redox dyshomeostasis promoted by tumor microenvironment (TME) modulation has become an appealing therapeutic target for cancer management. Herein, a dual plasmonic Au/SF@Cu_2-xS nanoreactor (abbreviation as ASC) is elaborately developed by covalent immobilization of sulfur defective Cu_2-xS nanodots onto the surface of silk fibroin (SF)-capped Au nanoparticles. Tumor hypoxia can be effectively alleviated by ASC-mediated local oxygenation, owing to the newfound catalase-mimic activity of Cu_2-xS. The semiconductor of Cu_2-xS with narrow bandgap energy of 2.54 eV enables a more rapid dissociation of electron-hole (e^-/h⁺) pair for a promoted US-triggered singlet oxygen (¹O₂) generation, in the presence of Au as electron scavenger. Moreover, Cu_2-xS is devote to Fenton-like reaction to catalyze H₂O₂ into ·OH under mild acidity and simultaneously deplete glutathione to aggravate intracellular oxidative stress. In another aspect, Au nanoparticles with glucose oxidase-mimic activity consumes intrinsic glucose, which contributes to a higher degree of oxidative damage and energy exhaustion of cancer cells. Importantly, such tumor starvation and ¹O₂ yield can be enhanced by Cu_2-xS-catalyzed O₂ self-replenishment in H₂O₂-rich TME. ASC-initiated M1 macrophage activation and therapy-triggered immunogenetic cell death (ICD) favors the systematic tumor elimination by eliciting antitumor immunity. This study undoubtedly enriches the rational design of SF-based nanocatalysts for medical utilizations.

Novel Microbial Palladium Nanoparticles with a High Photothermal Effect for Antibacterial Applications

Novel biocompatible palladium nanoparticles (Pd-NPs) have been prepared by microorganisms via Bacillus megaterium Y-4. It was demonstrated that ultrasonication treatment of biologically reduced Pd-NPs impart a much higher absorption in NIR regions and a better photothermal conversion efficiency to the material. The as-prepared material showed excellent biocompatibility and antibacterial activity under NIR irradiation. In less than 10 min, the disinfection efficiency for a low dosage of Pd-NPs (20 mg/L) was 99.99% toward both Staphylococcus aureus and Escherichia coli. The exclusive and even dispersed microbial Pd-NPs display a high efficiency of photothermal conversion under the irradiation of NIR, which endows them with excellent antibacterial activity in a low dosage.

Inorganic nanomaterials for intelligent photothermal antibacterial applications

Antibiotics are currently the main therapeutic agent for bacterial infections, but they have led to bacterial resistance, which has become a worldwide problem that needs to be addressed. The emergence of inorganic nanomaterials provides a new opportunity for the prevention and treatment of bacterial infection. With the continuous development of nanoscience, more and more inorganic nanomaterials have been used to treat bacterial infections. However, single inorganic nanoparticles (NPs) are often faced with problems such as large dosage, strong toxic and side effects, poor therapeutic effect and so on, so the combination of inorganic nano-materials and photothermal therapy (PTT) has become a promising treatment. PTT effectively avoids the problem of bacterial drug resistance, and can also reduce the dosage of inorganic nanomaterials to a certain extent, greatly improving the antibacterial effect. In this paper, we summarize several common synthesis methods of inorganic nanomaterials, and discuss the advantages and disadvantages of several typical inorganic nanomaterials which can be used in photothermal treatment of bacterial infection, such as precious metal-based nanomaterials, metal-based nanomaterials and carbon-based nanomaterials. In addition, we also analyze the future development trend of the remaining problems. We hope that these discussions will be helpful to the future research of near-infrared (NIR) photothermal conversion inorganic nanomaterials.

Remodeling of tumor microenvironment for enhanced tumor chemodynamic/photothermal/chemo-therapy

The anticancer treatment is largely affected by the microenvironment of the tumors, which not only resists the tumors to the thermo/chemo-therapy, but also promotes their growth and invasion. In this work, the angiogenesis factor is balanced by combining with the breathing hyperoxygen, for regulating the tumor microenvironment and also for relieving hypoxia and high tissue interstitial pressure, which promote drug delivery to tumor tissues by increasing the in vivo perfusion and reversing the immunosuppressive tumor. In addition, the designed multifunctional nanoparticles have a great potential for applications to the tumor dual-mode imaging including magnetic resonance (MR) and photoacoustic (PA) imaging. This work proposes a promising strategy to enhance the thermo/chemo-therapy efficacy by remodeling the tumor microenvironment, which would provide an alternative to prolong the lifetime of tumor patients.

Advanced Dual-Function Hollow Copper-Sulfide-Based Polyimide Composite Window Film Combining Near-Infrared Thermal Shielding and Organic Pollutants' Photodegradation

Window-film-integrated, near-infrared (NIR) absorption-based nanomaterials are of great interest in terms of numerous demands to reduce energy consumption, especially in buildings and vehicles. However, the question of how to effectively manage thermal energy generated from NIR harvesting in light-absorbing materials, rather than being wasted or causing negative effects, remains challenging. Herein, hollow copper sulfide (Cu2-xS) on colorless polyimide (PI) films, enabling them to be well-dispersed and robustly adhered, underwent in situ growth fabrication and were utilized as NIR-thermal-shielding and organic-pollutant-removal dual-function window films. Due to strong NIR absorbance, arising from the heavy hole-doping (copper cation deficiency), the Cu2-xS/PI composite film exhibited great promise for use in the filtration of the NIR spectrum. By monitoring Cu2-xS densities, its NIR-shielding efficiency reached 69.4%, with hundred-percent UV blocking and consistent performance within the reliability (85 °C/85%RH) tests over one week as well as 5000 bending cycles. The integration of the films into model cars and building windows exhibited excellent thermal-shielding performance upon exposure to direct sunlight. Moreover, benefiting from the distinctive distribution of Cu2-xS, the additional thermal energy (holes) generated in NIR absorption was successfully utilized. The densely surface-confined hollow structure of Cu2-xS on PI significantly endowed good formaldehyde catalytic capacity, with removal efficiency reaching approximately 72% within 60 min and a negligible decline after quartic reuse. These integration methodologies enable the promising fabrication of a high-performance, bifunctional window film combining thermal shielding and indoor organic pollutant removal.

Self-assembled NIR-responsive MoS2@quaternized chitosan/nanocellulose composite paper for recyclable antibacteria

Paper products are widely used in daily life, while the lack of antibacterial activity has made them become some disease transmission media. Herein, we introduced NIR-responsive molybdenum disulfide nanosheets (MoS₂) to endow nanocellulose paper antibacterial activity by electrostatic self-assembly with quaternized chitosan (QCS). Firstly, the MoS₂ nanosheets were exfoliated and stabilized with QCS under ultrasonication. The strong coordination between QCS and MoS₂ as well as the electrostatic attraction between QCS and cellulose nanofiber (CNF) helped to fabricate the MoS₂@QCS/CNF composite paper. The MoS₂@QCS/CNF composite paper exhibited excellent photothermal and photodynamic activity, achieving over 99.9% antibacterial efficacy against both E. coli and S. aureus, respectively. The hyperthermia induced by MoS₂ accelerated the glutathione (GSH) consumption and the reactive oxygen species (ROS)-independent oxidative stress destroyed the bacteria membranes integrity, synergistically leading to the malondialdehyde (MDA) oxidation and protein leakage to inhibit the bacteria growth. Importantly, the self-assembled fibrous network incorporating with the photo-stable antibacterial MoS₂ enabled the flexible composite paper with excellent mechanical strength and recyclability for long-term antimicrobial, possessing over 99.9% inhibition even after five cycles. No cell cytotoxicity was observed for the MoS₂@QCS/CNF composite paper, suggesting the potential of composite paper for bacterial infection control.

Anisotropic dual-plasmonic hetero-nanostructures with tunable plasmonic coupling effects

The influence of plasmonic coupling effects between different components in Au NRs@Cu2-x Se nanostructures on their characteristics was studied. To this aim, anisotropic Au@Cu2-x Se hetero-nanostructures with well-controlled design and optical properties were obtained. The LSPR bands of gold and copper selenide are superpositioned in the NIR region, resulting in superior photocatalytic properties of the nanostructures.

Interfacing metal-polyphenolic networks upon photothermal gold nanorods for triplex-evolved biocompatible bactericidal activity

Gold nanorods (GNRs) outstand in photothermal disinfection but are faced with severe surface chemistry and dose relevant biotoxicity. Herein, a naturally green building block, metal-phenolic networks (MPNs), was employed to functionalize GNRs via coordination reaction, yielding a tunable and biocompatible core-shell photothermal nano-bactericide (GNRs@MPNs). The bioactive GNRs@MPNs built with iron and polyphenols (tannic acid, epigallocatechin gallate, and procyanidins) exhibited superior light-to-heat conversion efficiencies with η = 29.29-44.00%, remarkably preceding that of GNRs (η = 12.24%), which could rapidly ablate 99.8% of Escherichia coli O157: H7 and 98.6% of Staphylococcus aureus bacteria in relatively low efficacy doses (10 ppm of Au). Moreover, local heat triggered by GNRs@MPNs accelerated the healing of the cutaneous wound of a mice model infected by methicillin-resistant S. aureus. The facile synthesis, photothermal synergy, polyphenolic bioactivity, and significantly low efficacy dose of GNRs@MPNs empower them satisfactory efficiency and biosafety in the future broad-spectrum photothermal sterilization applications.

Targeted Phototherapy by Niobium Carbide for Mammalian Tumor Models Similar to Humans

BACKGROUND

In the past few decades, nanomaterial-mediated phototherapy has gained significant attention as an alternative antitumor strategy. However, its antitumor success is majorly limited to the treatment of subcutaneous tumors in nude mice. In fact, no studies have been previously conducted in this area/field on clinically-relevant big animal models. Therefore, there is an urgent need to conduct further investigation in a typical big animal model, which is more closely related to the human body.

RESULTS

In this study, niobium carbide (NbC) was selected as a photoactive substance owing to the presence of outstanding near-infrared (NIR) absorption properties, which are responsible for the generation of NIR-triggered hyperthermia and reactive oxygen species that contribute towards synergetic photothermal and photodynamic effect. Moreover, the present study utilized macrophages as bio-carrier for the targeted delivery of NbC, wherein phagocytosis by macrophages retained the photothermal/photodynamic effect of NbC. Consequently, macrophage-loaded NbC ensured/allowed complete removal of solid tumors both in nude mice and big animal models involving rabbits. Meanwhile, two-dimensional ultrasound, shave wave elastography (SWE), and contrast-enhanced ultrasound (CEUS) were used to monitor physiological evolution in tumor in vivo post-treatment, which clearly revealed the occurrence of the photoablation process in tumor and provided a new strategy for the surveillance of tumor in big animal models.

CONCLUSION

Altogether, the use of a large animal model in this study presented higher clinical significance as compared to previous studies.

Assembly of gold nanorods with L-cysteine reduced graphene oxide for highly efficient NIR-triggered photothermal therapy

Near-infrared (NIR) photothermal therapy is an effective partner to the chemotherapy of tumors with the merits of high therapeutic ability and slight side effect on normal tissues. Herein, we synthesized gold nanorods and assembled them with L-cysteine reduced graphene oxide (AuNR@Lcyst-rGO) for efficient photothermal therapy. The high therapeutic efficacy of AuNR@Lcyst-rGO can be due to the high photothermal effect of gold nanorods and reduced graphene oxide, and the synergistic effect of them. The nontoxicity of L-cysteine also guarantees the comfortable biocompatibility of reduced graphene oxide, which is essential for the photothermal absorber used in human tissue. The results demonstrate that assembly of gold nanorods with reduced graphene oxide (AuNR@Lcyst-rGO) is a promising photothermal agent with high efficient NIR-triggered photothermal therapy efficiency, excellent stability, superior biocompatibility.

Cu2-x Sx Capped AuCu Nanostars for Efficient Plasmonic Photothermal Tumor Treatment in the Second Near-Infrared Window

Plasmonic nanohybrids are promising photo energy conversion materials in photoelectronics and biomedicine, due to their unique surface plasmon resonance (SPR). Au and Cu_2-x S_x nanostructures with strong SPR in the near-infrared (NIR) spectral region are classic plasmonic systems used to convert NIR photons into heat for photothermal therapy (PTT). The rational design of the Au/Cu_2-x S_x nanohybrids is expected to induce better photothermal conversion; however, the construction of such hybrids via wet-chemistry methods with a well-controlled interfacial structure is still challenging. Here, the synthesis of an AuCu Star/Cu_2-x S_x nanohybrid is reported, where the Cu_2-x S_x components are selectively grown on the AuCu nanostar tips to form "caps". The spatial formation of the Cu_2-x S_x caps on star tips is mainly governed by surfactant concentration, tip curvature, and experimental manipulation. The nanohybrids show low cytotoxicity and superior photothermal conversion efficiency, enabling robust PTT to kill cancer cells in the second NIR window. Numerical simulation reveals that the coupling of Cu_2-x S_x on nanostar tips generates strong interfacial electric field, improving photothermal conversion. Moreover, the spatial separation structure favors the continuous flow of hot charge carriers to produce active radicals, further promoting the tumor treatment effect.

Boosting Photothermal Theranostics via TICT and Molecular Motions for Photohyperthermia Therapy of Muscle-Invasive Bladder Cancer

The development of photothermal agents with high photothermal conversion efficiency (PCE) can help to reduce drug and laser dosage, but still remains a big challenge. Herein, a novel approach is reported to design photothermal agents with high PCE values by promoting nonradiative heat generation processes through the cooperation of twisted intramolecular charge transfer (TICT) and molecular motions. Within the designed molecule 2DMTT-BBTD, the tetraphenylethenes act as molecular rotors, the long alkyl chain grafted thiophene helps to twist the molecular geometry to facilitate TICT state formation and preserve molecular motions in aggregate, while the strong electron-withdrawing BBTD unit enhances TICT effect. 2DMTT-BBTD exhibits NIR-absorption and a high PCE value of 74.8% under 808 nm laser irradiation. Gambogic acid (GA) which surmounts tumor cell thermotolerance by inhibiting heat shock protein 90 (HSP90) expression is coloaded into the nanoparticles, RGD peptide is further introduced to the nanoparticle surface to improve tumor accumulation. The resultant nanoparticles facilitate the effective low-temperature hyperthermia therapy of muscle-invasive bladder cancer (MIBC) with minimal damage to surrounding heathy tissues. This work delivers a new design concept for development of highly efficient photothermal agents, which also provides a safer approach for noninvasive treatment of MIBC and other malignant tumors.

Tumor targeting and penetrating biomimetic mesoporous polydopamine nanoparticles facilitate photothermal killing and autophagy blocking for synergistic tumor ablation

The synergistic manipulation of autophagy blocking with tumor targeting and penetration effects to enhance cancer cell killing during photothermal therapy (PTT) remains a substantial challenge. Herein, we fabricated a biomimetic nanoplatform by precisely coating homologous prostate cancer cell membranes (CMs) onto the surface of mesoporous polydopamine nanoparticles (mPDA NPs) encapsulating the autophagy inhibitor chloroquine (CQ) for synergistically manipulating PTT and autophagy for anticancer treatment. The resulting biomimetic mPDA@CMs NPs-CQ system could escape macrophage phagocytosis, overcome the vascular barrier, and home in the homologous prostate tumor xenograft with high tumor targeting and penetrating efficiency. The mPDA NPs core endowed the mPDA@CMs NPs-CQ with good photothermal capability to mediate PTT killing of prostate cancer cells, while NIR-triggered CQ release from the nanosystem further arrested PTT-induced protective autophagy of cancer cells, thus weakening the resistance of prostate cancer cells to PTT. This combined PTT killing and autophagy blocking anticancer strategy could induce significant autophagosome accumulation, ROS generation, mitochondrial damage, endoplasmic reticulum stress, and apoptotic signal transduction, which finally results in synergistic prostate tumor ablation in vivo. This prostate cancer biomimetic nanosystem with synergistically enhanced anticancer efficiency achieved by manipulating PTT killing and autophagy blocking is expected to serve as a more effective anticancer strategy against prostate cancer. STATEMENT OF SIGNIFICANCE: Autophagy is considered as one of the most efficient rescuer and reinforcement mechanisms of cancer cells against photothermal therapy (PTT)-induced cancer cell eradication. How to synergistically manipulate autophagy blocking with significant tumor targeting and penetration to enhance PTT-mediated cancer cell killing remains a substantial challenge. Herein, we fabricated a biomimetic nanoplatform by precisely coating homologous cancer cell membranes onto the surface of mesoporous polydopamine nanoparticles with encapsulation of the autophagy inhibitor chloroquine for synergistic antitumor treatment with high tumor targeting and penetrating efficiency both in vitro and in vivo. This biomimetic nanosystem with synergistically enhanced anticancer efficiency by manipulating PTT killing and autophagy blocking is expected to serve as a more effective anticancer strategy.

PPy@Fe3O4 Nanoparticles Inhibit Tumor Growth and Metastasis Through Chemodynamic and Photothermal Therapy in Non-small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is considered to be a principal cause of cancer death across the world, and nanomedicine has provided promising alternatives for the treatment of NSCLC in recent years. Photothermal therapy (PTT) and chemodynamic therapy (CDT) have represented novel therapeutic modalities for cancer treatment with excellent performance. The purpose of this research was to evaluate the effects of PPy@Fe₃O₄ nanoparticles (NPs) on inhibiting growth and metastasis of NSCLC by combination of PTT and CDT. In this study, we synthesized PPy@Fe₃O₄ NPs through a very facile electrostatic absorption method. And we detected reactive oxygen species production, cell apoptosis, migration and protein expression in different groups of A549 cells and established xenograft models to evaluate the effects of PPy@Fe₃O₄ NPs for inhibiting the growth of NSCLC. The results showed that the PPy@Fe₃O₄ NPs had negligible cytotoxicity and could efficiently inhibit the cell growth and metastasis of NSCLC in vitro. In addition, the PPy@Fe₃O₄ NPs decreased tumor volume and growth in vivo and endowed their excellent MRI capability of observing the location and size of tumor. To sum up, our study displayed that the PPy@Fe₃O₄ NPs had significant synergistic effects of PTT and CDT, and had good biocompatibility and safety in vivo and in vitro. The PPy@Fe₃O₄ NPs may be an effective drug platform for the treatment of NSCLC.

Gold Nanorods: The Most Versatile Plasmonic Nanoparticles

Gold nanorods (NRs), pseudo-one-dimensional rod-shaped nanoparticles (NPs), have become one of the burgeoning materials in the recent years due to their anisotropic shape and adjustable plasmonic properties. With the continuous improvement in synthetic methods, a variety of materials have been attached around Au NRs to achieve unexpected or improved plasmonic properties and explore state-of-the-art technologies. In this review, we comprehensively summarize the latest progress on Au NRs, the most versatile anisotropic plasmonic NPs. We present a representative overview of the advances in the synthetic strategies and outline an extensive catalogue of Au-NR-based heterostructures with tailored architectures and special functionalities. The bottom-up assembly of Au NRs into preprogrammed metastructures is then discussed, as well as the design principles. We also provide a systematic elucidation of the different plasmonic properties associated with the Au-NR-based structures, followed by a discussion of the promising applications of Au NRs in various fields. We finally discuss the future research directions and challenges of Au NRs.

Photothermal nanozyme-ignited Fenton reaction-independent ferroptosis for breast cancer therapy

Ferroptosis is a type of programmed cell death caused by the iron-dependent lipid hydroperoxide pathway and has attracted significant interest. However, Fenton reaction-dependent ferroptosis has shown unsatisfactory therapeutic effects in tumor therapy, mainly due to inadequate reaction conditions in the tumor microenvironment. Here, we report a new strategy for Fenton-independent pathway by employing photothermal nanozyme to overcome limitations of the low efficiency of Fenton reaction. Specifically, we used iron redox pair (Fe²⁺/Fe³⁺)-containing hollow mesoporous Prussian blue (HMPB) nanocubes as the iron sources to fabricate iron-loaded liposome (HMPB@Lip). HMPB@Lip not only exerts the photothermal therapy, but also functions as nanozyme catalyzing lipid peroxidation for ferroptosis therapy. Importantly, Fenton reaction-independent ferroptosis triggered by photothermal nanozyme achieved effective tumor ablation. Therefore, HMPB@Lip can be used as a potential multifunctional nanozyme for effective Fenton reaction-independent ferroptosis therapy.

Applications of Aptamer-Bound Nanomaterials in Cancer Therapy

Cancer is still a major disease that threatens human life. Although traditional cancer treatment methods are widely used, they still have many disadvantages. Aptamers, owing to their small size, low toxicity, good specificity, and excellent biocompatibility, have been widely applied in biomedical areas. Therefore, the combination of nanomaterials with aptamers offers a new method for cancer treatment. First, we briefly introduce the situation of cancer treatment and aptamers. Then, we discuss the application of aptamers in breast cancer treatment, lung cancer treatment, and other cancer treatment methods. Finally, perspectives on challenges and future applications of aptamers in cancer therapy are discussed.

Optothermal properties of plasmonic inorganic nanoparticles for photoacoustic applications

Plasmonic systems are becoming a favourable alternative to dye molecules in the generation of photoacoustic signals for spectroscopy and imaging. In particular, inorganic nanoparticles are appealing because of their versatility. In fact, as the shape, size and chemical composition of nanoparticles are directly correlated with their plasmonic properties, the excitation wavelength can be tuned to their plasmon resonance by adjusting such traits. This feature enables an extensive spectral range to be covered. In addition, surface chemical modifications can be performed to provide the nanoparticles with designed functionalities, e.g., selective affinity for specific macromolecules. The efficiency of the conversion of absorbed photon energy into heat, which is the physical basis of the photoacoustic signal, can be accurately determined by photoacoustic methods. This review contrasts studies that evaluate photoconversion in various kinds of nanomaterials by different methods, with the objective of facilitating the researchers' choice of suitable plasmonic nanoparticles for photoacoustic applications.

Hyperspectral-enhanced dark field analysis of individual and collective photo-responsive gold-copper sulfide nanoparticles

We used hyperspectral-enhanced dark field microscopy for studying physicochemical changes in biomaterials by tracking their unique spectral signatures along their pathway through different biological environments typically found in any biomedical application. We correlate these spectral signatures with discrete environmental features causing changes in nanoparticles' physicochemical properties. We use this correlation to track the nanoparticles intracellularly and to assess the impact of these changes on their functionality. We focus on one example of a photothermal nanocomposite, i.e., polymer-coated gold/copper sulfide nanoparticles, because their performance depends on their localized surface plasmon peak, which is highly sensitive to environmental changes. We found spectral differences both in the dependence of time and discrete environmental factors, affecting the range of illumination wavelengths that can be used to activate the functionality of these types of nanoparticles. The presence of proteins (protein corona) and the increase in ionic strength induce a spectral broadening towards the NIR region which we associated with nanoparticles' agglomeration. In acidic environments, such as that of the lysosome, a red shift was also observed in addition to a decrease in the scattering intensity probably associated with a destabilization of the proteins and/or the change in the net charge of the polymer around the nanoparticles. We observed a loss of the photo-excitation potential of those nanoparticles exposed to acidic conditions in the <600 nm spectral rage. In a similar manner, ageing induces a transitioning from a broad multipeak spectrum to a distinct shoulder with time (up to 8 months) with the loss of spectral contribution in the 450-600 nm range. Hence, a fresh preparation of nanoparticles before their application would be recommended for an optimal performance. We highlight the impact of ageing and the acidic environment on the responsiveness of this type of plasmonic nanoparticle. Regardless of the spectral differences found, polymer-coated gold/copper sulfide nanoparticles retained their photothermal response as demonstrated in vitro upon two-photon irradiation. This could be ascribed to their robust geometry provided by the polymer coating. These results should be useful to rationally design plasmonic photothermal probes.

A plasmon-enhanced theranostic nanoplatform for synergistic chemo-phototherapy of hypoxic tumors in the NIR-II window

Development of simple and effective synergistic therapy by combination of different therapeutic modalities within one single nanostructure is of great importance for cancer treatment. In this study, by integrating the anticancer drug DOX and plasmonic bimetal heterostructures into zeolitic imidazolate framework-8 (ZIF-8), a stimuli-responsive multifunctional nanoplatform, DOX-Pt-tipped Au@ZIF-8, has been successfully fabricated. Pt nanocrystals with catalase-like activity were selectively grown on the ends of the Au nanorods to form Pt-tipped Au NR heterostructures. Under single 1064 nm laser irradiation, compared with Au NRs and Pt-covered Au NRs, the Pt-tipped Au nanorods exhibit outstanding photothermal and photodynamic properties owing to more efficient plasmon-induced electron-hole separation. The heat generated by laser irradiation can enhance the catalytic activity of Pt and improve the O2 level to relieve tumor hypoxia. Meanwhile, the strong absorption in the NIR-II region and high-Z elements (Au, Pt) of the DOX-Pt-tipped Au@ZIF-8 provide the possibility for photothermal (PT) and computed tomography (CT) imaging. Both in vitro and in vivo experimental results illustrated that the DOX-Pt-tipped Au@ZIF-8 exhibits remarkably synergistic plasmon-enhanced chemo-phototherapy (PTT/PDT) and successfully inhibited tumor growth. Taken together, this work contributes to designing a rational theranostic nanoplatform for PT/CT imaging-guided synergistic chemo-phototherapy under single laser activation.

Dual Plasmonic Au-Cu2-x S Nanocomposites: Design Strategies and Photothermal Properties

Coupling two different materials to create a hybrid nanostructured system is a powerful strategy for achieving synergistically enhanced properties and advanced functionalities. In the case of Au and Cu_2-x S, their combination on the nanoscale results in dual plasmonic Au-Cu_2-x S nanocomposites that exhibit intense photon absorption in both the visible and the near-infrared spectral ranges. Their strong light-absorbing properties translate to superior photothermal transduction efficiency, making them attractive in photothermal-based applications. There are several nanostructure configurations that are possible for the Au-Cu_2-x S system, and the successful fabrication of a particular architecture often requires a carefully planned synthetic strategy. In this Minireview, the different synthetic approaches that can be employed to produce rationally designed Au-Cu_2-x S nanocomposites are presented, with a focus on the experimental protocols that can lead to heterodimer, core-shell, reverse core-shell, and yolk-shell configurations. The photothermal behavior of these materials is also discussed, providing a glimpse of their potential use as photothermally active agents in therapeutic and theranostic applications.

Noncovalent Self-Assembled Smart Gold(III) Porphyrin Nanodrug for Synergistic Chemo-Photothermal Therapy

Self-assembly is a powerful means to fabricate multifunctional smart nanotheranostics. However, the complicated preparation, toxicity of responsive carriers, and low loading efficiency of drug cargo hinder the outcome. Herein, we developed a responsive carrier-free noncovalent self-assembly strategy of a metallized Au(III) tetra-(4-pyridyl) porphine (AuTPyP) anticancer drug for the preparation of a heat/acid dual-stimulated nanodrug, and it generated a better photothermal effect than monomers under irradiation. The photothermal effect promoted the protonation of the hydrophobic pyridyl group and the following release into tumorous acidic microenvironments. With cRGD modification, the released drug induced the aggravation of intracellular reactive oxygen species (ROS) via the activity inhibition of thioredoxin reductase (TrxR) for synergistic chemo-photothermal therapy of tumors.

Beyond the Visible: Bioinspired Infrared Adaptive Materials

Infrared (IR) adaptation phenomena are ubiquitous in nature and biological systems. Taking inspiration from natural creatures, researchers have devoted extensive efforts for developing advanced IR adaptive materials and exploring their applications in areas of smart camouflage, thermal energy management, biomedical science, and many other IR-related technological fields. Herein, an up-to-date review is provided on the recent advancements of bioinspired IR adaptive materials and their promising applications. First an overview of IR adaptation in nature and advanced artificial IR technologies is presented. Recent endeavors are then introduced toward developing bioinspired adaptive materials for IR camouflage and IR radiative cooling. According to the Stefan-Boltzmann law, IR camouflage can be realized by either emissivity engineering or thermal cloaks. IR radiative cooling can maximize the thermal radiation of an object through an IR atmospheric transparency window, and thus holds great potential for use in energy-efficient green buildings and smart personal thermal management systems. Recent advances in bioinspired adaptive materials for emerging near-IR (NIR) applications are also discussed, including NIR-triggered biological technologies, NIR light-fueled soft robotics, and NIR light-driven supramolecular nanosystems. This review concludes with a perspective on the challenges and opportunities for the future development of bioinspired IR adaptive materials.

Noble Metal Nanomaterials for NIR-Triggered Photothermal Therapy in Cancer

It is of great significance to develop anticancer therapeutic agents or technologies with high degree of specificity and patient compliance, while low toxicity. The emerging photothermal therapy (PTT) has become a new and powerful therapeutic technology due to its noninvasiveness, high specificity, low side effects to normal tissues and strong anticancer efficacy. Noble metal nanomaterials possess strong surface plasmon resonance (SPR) effect and synthetic tunability, which make them facile and effective PTT agents with superior optical and photothermal characteristics, such as high absorption cross-section, incomparable optical-thermal conversion efficiency in the near infrared (NIR) region, as well as the potential of bioimaging. By incorporating with various functional reagents such as antibodies, peptides, biocompatible polymers, chemo-drug and immune factors, noble metal nanomaterials have presented strong potential in multifunctional cancer therapy. Herein, the recent development regarding the application of noble metal nanomaterials for NIR-triggered PTT in cancer treatment is summarized. A variety of studies with good therapeutic effects against cancer from impressive photothermal efficacy of noble metal nanomaterials are concluded. Intelligent nanoplatforms through ingenious fabrication showing potential of multifunctional PTT, combined with chemo-therapy, immunotherapy, photodynamic therapy (PDT), as well as simultaneous imaging modality are also demonstrated.

Metal-Free Organo-Theranostic Nanosystem with High Nitroxide Stability and Loading for Image-Guided Targeted Tumor Therapy

The desire for all-organic-composed nanoparticles (NPs) of considerable biocompatibility to simultaneously diagnose and treat cancer is undeniably interminable. Heretofore, metal-based agents dominate the landscape of available magnetic resonance imaging (MRI) contrast agents and photothermal therapeutic agents, but with associated metal-specific downsides. Here, an all-organic metal-free nanoprobe, whose appreciable biocompatibility is synergistically contributed by its tetra-organo-components, is developed as a viable alternative to metal-based probes for MRI-guided tumor-targeted photothermal therapy (PTT). This rationally entails a glycol chitosan (GC)-linked polypyrrole (PP) nanoscaffold that provides abundant primary and secondary amino groups for amidation with the carboxyl groups in a nitroxide radical (TEMPO) and folic acid (FA), to obtain GC-PP@TEMPO-FA NPs. Advantageously, the appreciably benign GC-PP@TEMPO-FA features high nitroxide loading (r₁ = 1.58 mM^-1 s^-1) and in vivo nitroxide-reduction resistance, prolonged nitroxide-systemic circulation times, appreciable water dispersibility, potential photodynamic therapeutic and electron paramagnetic resonance imaging capabilities, considerable biocompatibility, and ultimately achieves a 17 h commensurate MRI contrast enhancement. Moreover, its GC component conveys a plethora of PP to tumor sites, where FA-mediated tumor targeting enables substantial NP accumulation with consequential near-complete tumor regression within 16 days in an MRI-guided PTT. The present work therefore promotes the engineering of organic-based metal-free biocompatible NPs in synergism, in furtherance of tumor-targeted image-guided therapy.

Bistratal Au@Bi2S3 nanobones for excellent NIR-triggered/multimodal imaging-guided synergistic therapy for liver cancer

To fabricate a highly biocompatible nanoplatform enabling synergistic therapy and real-time imaging, novel Au@Bi2S3 core shell nanobones (NBs) (Au@Bi2S3 NBs) with Au nanorods as cores were synthesized. The combination of Au nanorods with Bi2S3 film made the Au@Bi2S3 NBs exhibit ultrahigh photothermal (PT) conversion efficiency, remarkable photoacoustic (PA) imaging and high computed tomography (CT) performance; these Au@Bi2S3 NBs thus are a promising nanotheranostic agent for PT/PA/CT imaging. Subsequently, poly(N-vinylpyrrolidone)-modified Au@Bi2S3 NBs (Au@Bi2S3-PVP NBs) were successfully loaded with the anticancer drug doxorubicin (DOX), and a satisfactory pH sensitive release profile was achieved, thus revealing the great potential of Au@Bi2S3-PVP NBs in chemotherapy as a drug carrier to deliver DOX into cancer cells. Both in vitro and in vivo investigations demonstrated that the Au@Bi2S3-PVP NBs possessed multiple desired features for cancer therapy, including extremely low toxicity, good biocompatibility, high drug loading ability, precise tumor targeting and effective accumulation. Highly efficient ablation of the human liver cancer cell HepG2 was achieved through Au@Bi2S3-PVP NB-mediated photothermal therapy (PTT). As both a contrast enhancement probe and therapeutic agent, Au@Bi2S3-PVP NBs provided outstanding NIR-triggered multi-modal PT/PA/CT imaging-guided PTT and effectively inhibited the growth of HepG2 liver cancer cells via synergistic chemo/PT therapy.

Strategies for the functionalisation of gold nanorods to reduce toxicity and aid clinical translation

Gold nanorods (GNRs) show great promise as photothermal therapy agents due to their remarkable ability to convert light into heat. In most cases, gold nanorods are synthesised via a seed-mediated method assisted by surfactants. However, the toxicity of these surfactants, principally cetrimonium ions, has prevented GNRs from being used more widely in vivo. To address this issue, various detoxification and functionalisation approaches have been proposed in recent years to replace or cover surfactant coatings on the gold surface. In this short review, the advantages and limitations of each approach are examined in the context of the recent progress made towards the design of GNRs suitable for use in the body.

Second near-infrared photothermal materials for combinational nanotheranostics

This review summarizes the recent development of second near-infrared photothermal combinational nanotheranostics for cancer, infectious diseases and regenerative medicine.

Gold nanoclusters modified mesoporous silica coated gold nanorods: Enhanced photothermal properties and fluorescence imaging

Photothermal therapy (PTT) is a non-invasive therapy that is widely used in cancer treatment. Gold nanorods (AuNRs) are particularly suitable as a photothermal reagent due to their unique localized surface plasmon resonance (LSPR) properties. However, bare gold nanorods are not stable enough during radiation to collect enough energy to kill tumor cells. In addition, they showed some biologically toxic originated from the poor colloidal stability and surfactants cetyltrimethyl ammonium bromide (CTAB), making it difficult to apply them directly to clinical research. To solve these problems, a novel nanocomposite was structured by coating silica shell and gold nanocluster on the outer layer of the gold nanorod (AuNRs@SiO₂@AuNCs). Compared with the bare gold nanorod, the nanocomposite with the core-shell structure showed superior photothermal effect. The photothermal conversion temperature reached 63 °C under a lower irradiation power. The photothermal conversion efficiency was enhanced to 77.6%. Its photothermal performance remained constant after five cycles of near-infrared laser irradiation, indicating excellent photothermal stability. In vitro cell imaging experiments show that AuNRs@SiO₂@ AuNCs can effectively enter tumor cells. By 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) analysis, cancer cells can be effectively killed when exposed to a near-infrared laser. During the synthesis process, the silica and gold nanoclusters replaced the toxic CTAB molecular layer on the surface of AuNRs. Therefore, AuNRs@SiO₂@AuNCs has good biocompatibility and fluorescence characteristics. These results suggest that such AuNRs@SiO₂@AuNCs nanocomposite shows great potential in imaging guided photothermal therapy for cancer.