Rationally designed dual-plasmonic gold nanorod@cuprous selenide hybrid heterostructures by regioselective overgrowth for in vivo photothermal tumor ablation in the second near-infrared biowindow

Surface engineered nanohybrids in plasmonic photothermal therapy for cancer: Regulatory and translational challenges

Plasmonic materials as non-invasive and selective treatment strategies are gaining increasing attention in the healthcare sector due to their remarkable optical and electronic properties, where the interface between matter and light becomes enhanced and highly localized. Some attractive applications of plasmonic materials in healthcare include drug delivery to target specific tissues or cells, hence reducing the side effects of the drug and improving their efficacy; enhancing the contrast and resolution in bioimaging; and selectively heating and destroying the cancerous cells while parting the healthy cells. Despite such advancements in photothermal therapy for cancer treatment, some limitations are still challenging. These include poor photothermal conversion efficiency, heat resistance, less accumulation in the tumor microenvironment, poor biosafety of photothermal agents, damage to the surrounding healthy tissues, post-treatment inflammatory responses, etc. Even though the clinical application of photothermal therapy is primarily restricted due to poor tissue penetration of excitation light, enzyme therapy is hindered due to less therapeutic efficacy. Several multimodal strategies, including chemotherapy, radiotherapy, photodynamic therapy, and immunotherapy were developed to circumvent these side effects associated with plasmonic photothermal agents for effective mild-temperature photothermal therapy. It can be prophesied that the nanohybrid platform could pave the way for developing cutting-edge multifunctional precise nanomedicine via an ecologically sustainable approach towards cancer therapy. In the present review, we have highlighted the significant challenges of photothermal therapy from the laboratory to the clinical setting and their struggle to get approval from the Food and Drug Administration (FDA).

Thermally Induced Domain Migration and Interfacial Restructuring in Cation Exchanged ZnS-Cu1.8S Heterostructured Nanorods

Partial cation exchange reactions can be used to rationally design and synthesize heterostructured nanoparticles that are useful targets for applications in photocatalysis, nanophotonics, thermoelectrics, and medicine. Such reactions introduce intraparticle frameworks that define the spatial arrangements of different materials within a heterostructured nanoparticle, as well as the orientations and locations of their interfaces. Here, we show that upon heating to temperatures relevant to their synthesis and applications, the ZnS regions and Cu1.8S/ZnS interfaces of heterostructured ZnS-Cu1.8S nanorods migrate and restructure. We first use partial cation exchange reactions to synthesize a library of seven distinct samples containing various patches, bands, and tips of ZnS embedded within Cu1.8S nanorods. Upon annealing in solution or in air, ex situ TEM analysis shows evidence that the ZnS domains migrate in different ways, depending upon their sizes and locations. Using differential scanning calorimetry, we correlate the threshold temperature for ZnS migration to the superionic transition temperature of Cu1.8S, which facilitates rapid diffusion throughout the nanorods. We then use in situ thermal TEM to study the evolution of individual ZnS-Cu1.8S nanorods upon heating. We find that ZnS domain migration occurs through a ripening process that minimizes small patches with higher-energy interfaces in favor of larger bands and tips having lower-energy interfaces, as well as through restructuring of higher-energy Cu1.8S/ZnS interfaces. Notably, Cu1.8S nanorods containing multiple patches of ZnS thermally transform into ZnS-Cu1.8S heterostructured nanorods having ZnS tips and/or central bands, which provides mechanistic insights into how these commonly observed products form during synthesis.

Gold-semiconductor nanohybrids as advanced phototherapeutics

Phototherapeutics is gaining momentum as a mainstream treatment for cancer, with gold-semiconductor nanocomposites showing promise as potent phototherapeutic agents due to their structural tunability, biocompatibility and functional diversity. Such nanohybrids possess plasmonic characteristics in the presence of gold and the catalytic nature of semiconductor units, as well as the unexpected physicochemical properties arising from the contact interface. This perspective provides an overview of the latest research on gold-semiconductor nanocomposites for photodynamic, photothermal and photocatalytic therapy. The relationship between the spatial configuration of these nanohybrids and their practical performance was explored to deliver comprehensive insights and guidance for the design and fabrication of novel composite nanoplatforms to enhance the efficiency of phototherapeutics, promoting the development of nanotechnology-based advanced biomedical applications.

Pristine, Ni- and Zn-Doped CuSe Nanoparticles: An Antimicrobial, Antioxidant, and Cytotoxicity Study

The strategy of chemical coprecipitation is implemented to synthesize nanoparticles of pristine CuSe, 5 and 10% Ni-doped CuSe, and 5 and 10% Zn-doped CuSe. All of the nanoparticles are found to be near stoichiometric by the evaluation of X-ray energy using electron dispersion spectra, and the elemental mapping shows uniform distribution. By X-ray diffraction examination, all of the nanoparticles are identified as being single-phase and having a hexagonal lattice structure. Field emission microscopy with electrons in both scanning and transmission modes affirmed the spherical configuration of the nanoparticles. The crystalline nature of the nanoparticles is confirmed by the presence of spot patterns observed in the selected area electron diffraction patterns. The observed d value matches well with the d value of the CuSe hexagonal (102) plane. Findings from dynamic light scattering reveal the size distribution of nanoparticles. The nanoparticle's stability is investigated by ζ potential measurements. Pristine and Ni-doped CuSe nanoparticles exhibit ζ potential values in the preliminary stability band of ±10 to ±30 mV, while Zn-doped nanoparticles feature moderate stability levels of ±30 to ±40 mV. The potent antimicrobial effects of synthesized nanoparticles are studied against Staphylococcus aureus, Pseudomonas aeruginosa, Proteus vulgaris, Enterobacter aerogenes, and Escherichia coli bacteria. The 2,2-diphenyl-1-picrylhydrazyl scavenging test is used to investigate the nanoparticle's antioxidant activities. The results showed the highest activity for control (Vitamin C) with an IC₅₀ value of 43.6 μg/mL, while the lowest for Ni-doped CuSe nanoparticles with an IC₅₀ value of 106.2 μg/mL. Brine shrimps are utilized for in vivo cytotoxicity evaluation of the synthesized nanoparticles, which demonstrates that 10% Ni- and 10% Zn-doped CuSe nanoparticles are more damaging on brine shrimp instead on other nanoparticles with a 100% mortality rate. The lung cancer cell line of human (A549) is used to investigate in vitro cytotoxicity. The results indicate that pristine CuSe nanoparticles are more effective in the context of cytotoxicity against the A549 cell lines, possessing an IC₅₀ of 488 μg/mL. The particulars of the outcomes are explained in depth.

Metal selenide nanomaterials for biomedical applications

Metal selenide nanomaterials have received enormous attention as they possess diverse compositions, microstructures, and properties. The combination of selenium with various metallic elements gives the metal selenide nanomaterials distinctive optoelectronic and magnetic properties, such as strong near-infrared absorption, excellent imaging properties, good stability, and long in vivo circulation. This makes metal selenide nanomaterials advantageous and promising for biomedical applications. This paper summarizes the research progress in the last five years in the controlled synthesis of metal selenide nanomaterials in different dimensions and with different compositions and structures. Then we discuss how surface modification and functionalization strategies are well-suited for biomedical fields, including tumor therapy, biosensing, and antibacterial biological applications. The future trends and issues of metal selenide nanomaterials in the biomedical field are also discussed.

Early diagnosis of bladder cancer by photoacoustic imaging of tumor-targeted gold nanorods

Detection and removal of bladder cancer lesions at an early stage is crucial for preventing tumor relapse and progression. This study aimed to develop a new technological platform for the visualization of small and flat urothelial lesions of high-grade bladder carcinoma in situ (CIS). We found that the integrin α5β1, overexpressed in bladder cancer cell lines, murine orthotopic bladder cancer and human bladder CIS, can be exploited as a receptor for targeted delivery of GNRs functionalized with the cyclic CphgisoDGRG peptide (Iso4). The GNRs@Chit-Iso4 was stable in urine and selectively recognized α5β1 positive neoplastic urothelium, while low frequency ultrasound-assisted shaking of intravesically instilled GNRs@Chit-Iso4 allowed the distribution of nanoparticles across the entire volume of the bladder. Photoacoustic imaging of GNRs@Chit-Iso4 bound to tumor cells allowed for the detection of neoplastic lesions smaller than 0.5 mm that were undetectable by ultrasound imaging and bioluminescence.

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

The influence of plasmonic coupling effects between different components in Au NRs@Cu_2-x Se nanostructures on their characteristics was studied. To this aim, anisotropic Au@Cu_2-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.

Near-Infrared II Plasmonic Phototheranostics with Glutathione Depletion for Multimodal Imaging-Guided Hypoxia-Tolerant Chemodynamic-Photocatalytic-Photothermal Cancer Therapy Triggered by a Single Laser

Tumor microenvironment (TME)-activatable phototheranostics is highly desirable in cancer management but still remains challenging for clinical applications owing to the lack of multifunctional theranostic agents and the limited tissue penetration depth. Reported here is an "all-in-one" phototheranostic platform based on near-infrared II (NIR-II) dual-plasmonic Au@Cu_2-x Se core-shell nanocrystals (dpGCS NCs) for combined photoacoustic (PA)/photothermal (PT) imaging-guided chemodynamic therapy (CDT)/photocatalytic therapy (PCT)/photothermal therapy (PTT) all triggered by a single NIR-II laser. The dpGCS NCs feature excellent NIR-II plasmonic and PT properties, which guarantee their capabilities of NIR-II PA and PT imaging for real-time visual observation of tumor size and location during cancer treatment. Additionally, the TME-activated in situ •OH production via dpGCS NC-catalyzed Fenton-like reaction is further enhanced by the NIR-II irradiation, while photoexcited plasmonic hole-induced formation of extra •OH is also evidenced for PCT. Both in vitro and in vivo experiments confirm remarkable therapeutic efficacy of the present phototheranostic platform under NIR-II laser through the CDT/PCT/PTT trimodal combination therapy, achieving complete inhibition of tumor growth in tumor-bearing mice after administration of dpGCS NCs plus a single NIR-II laser irradiation. This work provides a distinctive paradigm for the development of NIR-II phototheranostic platforms for imaging-guided cancer therapy using a single laser.

Preparation of a gold@europium-based coordination polymer nanocomposite with excellent photothermal properties and its potential for four-mode imaging

A nanocomposite was synthesized by replacing the toxic CTAB on the surface of GNRs with a europium-based hyaluronic acid coordination polymer. The nanocomposite exhibits excellent photothermal performance and also has potential for four-mode imaging.

Soluble microneedle patch with photothermal and NO-release properties for painless and precise treatment of ischemic perforator flaps

Skin necrosis is the most serious complication of flap plastic surgery, which means the failure of the operation. Systemic administration rarely benefits the local area and can lead to side effects, while topical administration has poor permeability due to the skin barrier function. Currently, few of these common medical interventions can totally respond to the blood supply of the skin after surgery. Herein, a soluble microneedle (MN) patch made of hyaluronic acid was used to target the ischemic area in a painless and precise manner for transdermal drug delivery. Based on the important role of nitric oxide (NO) in angiogenesis, the thermosensitive NO donor (BNN6) and gold nanorods (GNRs) acting as photothermal agents were introduced into the microneedles (MNs). The hyperthermia induced by GNRs under near infrared (NIR, 808 nm) irradiation could enhance the penetration of drugs and facilitate NO release from BNN6. A series of corresponding experiments proved that the system played a significant promotion role in vascular regeneration, providing a painless, precise and NO-assisted treatment method for the ischemic perforator flaps.

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.

Ansamitocin P3-Loaded Gold-NanoCage Conjugated with Immune Checkpoint Inhibitor to Enhance Photo-Chemo-Thermal Maturation of Dendritic Cells for Hepatocellular Carcinoma

Immunotherapy is a newly developed method for cancer treatment, but still generates limited response in partial patients for hepatocellular carcinoma (HCC) because the immunity cycle is limited by the tumor microenvironment (TME). Herein, we introduce multifunctional gold nanocages (AuNCs)-based nanocarriers with Ansamitocin P3 (AP3) loaded and anti-PDL1 binding (AP3-AuNCs-anti-PDL1) which can combine photothermal therapy, chemotherapeutic agent-triggered DCs maturation, and checkpoint immunotherapy in one platform. The AP3-AuNCs-anti-PDL1 using Avidin-biotin to bind anti-PDL1 on the surface of AP3-AuNCs showed specifically cellular targeting compared to AuNCs, which can increase the immune responses. The AP3-AuNCs+NIR-10 min exhibited the highly activated DCs maturation with two-fold higher than control+NIR, which can be attributed to the significant release of AP3. The results illustrated the synergistic effect of tumor-associated antigens (TAAs) and controlled AP3 release under near infrared (NIR) in triggering effective DCs maturation. Among them, AP3 release played the more important role than the TAAs under PTT in promoting T-cell activation. These results illustrate the promising potential of AuNCs-based nanocarriers combined with AP3 and the checkpoint inhibitors to strengthen the positive loop of immunity cycle.

Near-Infrared II Thermoplasmonics of Cuprous Selenide Multilayer Nanoshells: The Role of the Plasmonic Core

We present a numerical investigation of the plasmonic and photothermal properties of two different types of cuprous selenide (Cu_2-xSe) concentric multilayer nanoshells (CMNSs), heteroCMNSs and homoCMNSs, comprising an outer Cu_2-xSe nanoshell and an intermediate silica layer but with a different nanoparticle core of either Au or Cu_2-xSe. Numerical calculations of optical absorption, near-field enhancement, and local temperature increase are performed with varied dimensions. The plasmon modes from both types of CMNSs are interpreted by combining the plasmon hybridization theory with the surface charge distribution. The two CMNSs exhibit remarkable near-infrared II (NIR-II) plasmonic properties tunable by controlling the interaction between the inner core and the Cu_2-xSe nanoshell. The distinct temperature increase distributions between the two CMNSs are identified at their NIR-II resonance wavelengths. The correlation between the partial absorption and the temperature increase of the inner core and Cu_2-xSe nanoshell suggests the thermal interplay between the components.