Carbon-Coated Gold Nanorods: A Facile Route to Biocompatible Materials for Photothermal Applications

Recent Developments in Metallic Degradable Micromotors for Biomedical and Environmental Remediation Applications

Synthetic micromotor has gained substantial attention in biomedicine and environmental remediation. Metal-based degradable micromotor composed of magnesium (Mg), zinc (Zn), and iron (Fe) have promise due to their nontoxic fuel-free propulsion, favorable biocompatibility, and safe excretion of degradation products Recent advances in degradable metallic micromotor have shown their fast movement in complex biological media, efficient cargo delivery and favorable biocompatibility. A noteworthy number of degradable metal-based micromotors employ bubble propulsion, utilizing water as fuel to generate hydrogen bubbles. This novel feature has projected degradable metallic micromotors for active in vivo drug delivery applications. In addition, understanding the degradation mechanism of these micromotors is also a key parameter for their design and performance. Its propulsion efficiency and life span govern the overall performance of a degradable metallic micromotor. Here we review the design and recent advancements of metallic degradable micromotors. Furthermore, we describe the controlled degradation, efficient in vivo drug delivery, and built-in acid neutralization capabilities of degradable micromotors with versatile biomedical applications. Moreover, we discuss micromotors' efficacy in detecting and destroying environmental pollutants. Finally, we address the limitations and future research directions of degradable metallic micromotors.

Nanoparticle-Mediated Photothermal Therapy Limitation in Clinical Applications Regarding Pain Management

The development of new effective cancer treatment methods has attracted much attention, mainly due to the limited efficacy and considerable side effects of currently used cancer treatment methods such as radiation therapy and chemotherapy. Photothermal therapy based on the use of plasmonically resonant metallic nanoparticles has emerged as a promising technique to eradicate cancer cells selectively. In this method, plasmonic nanoparticles are first preferentially uptaken by a tumor and then selectively heated by exposure to laser radiation with a specific plasmonic resonant wavelength, to destroy the tumor whilst minimizing damage to adjacent normal tissue. However, several parameters can limit the effectiveness of photothermal therapy, resulting in insufficient heating and potentially leading to cancer recurrence. One of these parameters is the patient's pain sensation during the treatment, if this is performed without use of anesthetic. Pain can restrict the level of applicable laser radiation, cause an interruption to the treatment course and, as such, affect its efficacy, as well as leading to a negative patient experience and consequential general population hesitancy to this type of therapy. Since having a comfortable and painless procedure is one of the important treatment goals in the clinic, along with its high effectiveness, and due to the relatively low number of studies devoted to this specific topic, we have compiled this review. Moreover, non-invasive and painless methods for temperature measurement during photothermal therapy (PTT), such as Raman spectroscopy and nanothermometry, will be discussed in the following. Here, we firstly outline the physical phenomena underlying the photothermal therapy, and then discuss studies devoted to photothermal cancer treatment concerning pain management and pathways for improved efficiency of photothermal therapy whilst minimizing pain experienced by the patient.

Ultrasmall gold nanorod-polydopamine hybrids for enhanced photoacoustic imaging and photothermal therapy in second near-infrared window

Gold nanorods (GNRs) have attracted great interest for photo-mediated biomedicines due to their tunable and high optical absorption, high photothermal conversion efficiency and facile surface modifiability. GNRs that have efficient absorption in second near-infrared (NIR-II) window hold further promise in bio-applications due to low background signal from tissue and deep tissue penetration. However, bare GNRs readily undergo shape deformation (termed as 'melting effect') during the laser illumination losing their unique localized surface plasmon resonance (LSPR) properties, which subsequently leads to PA signal attenuation and decreased photothermal efficiency. Polydopamine (PDA) is a robust synthetic melanin that has broad absorption and high photothermal conversion. Herein, we coated GNRs with PDA to prepare photothermally robust GNR@PDA hybrids for enhanced photo-mediated theranostic agents. Ultrasmall GNRs (SGNRs) and conventional large GNRs (LGNRs) that possess similar LSPR characteristics as well as GNR@PDA hybrids were compared side-by-side in terms of the size-dependent photoacoustic (PA) imaging, photothermal therapy (PTT), and structural stability. In vitro experiments further demonstrated that SGNR@PDA showed 95% ablation of SKOV3 ovarian cancer cells, which is significantly higher than that of LGNRs (66%) and SGNRs (74%). Collectively, our PDA coating strategy represents a rational design for enhanced PA imaging and efficient PTT via a nanoparticle, i.e., nanotheranostics.

Radiative Relaxation of Gold Nanorods Coated with Mesoporous Silica with Different Porosities upon Nanosecond Photoexcitation Monitored by Time-Resolved Infrared Emission Spectroscopy

Gold nanorods (AuNRs) have been widely used in photothermal conversion, and a coating of silica (SiO₂) provides higher thermal stability, better biocompatibility, and versatile chemical functionalization. In this work, two gold nanorods coated with surfactant-templated mesoporous silica layers of the same thickness but different porosities, and thus different specific surface areas, were prepared. Upon irradiation with 1064 nm nanosecond pulsed laser, the transient infrared emissions of AuNR@SiO₂ enveloped the stretching mode of the Si-O-Si bridge (1000-1250 cm^-1), the bending mode of adsorbed H₂O (1600-1650 cm^-1) within the mesoporous silica layer, and blackbody radiation, in terms of an underlying broad band (1000-2000 cm^-1) probed with a step-scan Fourier transform spectrometer. The mesoporous silica shell and the adsorbed H₂O gained populations of their vibrationally excited states, and the whole AuNR@SiO₂ was heated up via the photothermal energy of the core AuNRs. An average temperature after 5-10 μs within 80% of the emission intensity was ca. 200 °C. The decay of the emission at 1000-1250 and 1500-1750 cm^-1 was both accelerated, and the blackbody radiation components were negatively correlated with the porosity of the mesoporous silica layer. Higher porosity of the mesoporous silica layer was associated with more effective depopulation of the vibrationally excited states of the silica layers on the AuNRs via the nonradiative thermal conduction of the adsorbed H₂O, since H₂O has a larger thermal conduction coefficient than that of silica, in concomitance with the accelerated emission kinetics. This work unveils the roles of the porosity, capping materials, and entrapping molecules of a core-shell nanostructure during the thermalization after photoexcitation.

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.

Cathepsin B-responsive multifunctional peptide conjugated gold nanorods for mitochondrial targeting and precise photothermal cancer therapy

Nanomaterials have shown great potential in cancer therapy, but the phenomenon of poor tumor recognition without cellular organelle accumulation usually leads to reduced therapeutic effects and enhanced side effects. Herein, we resolved this issue by employing a multifunctional peptide coating mainly composed of, from the inside out, a mitochondrial targeting segment, a cathepsin B-responsive segment and a zwitterionic antifouling segment. Then gold nanorods were modified with a peptide via ligand exchange, displaying excellent photothermal property and superior stability both before and after enzyme treatment. The in vitro and in vivo results showed that this nanoplatform possessed good biocompatibility, satisfactory mitochondria targeting ability, prolonged blood circulation lifetime and enhanced cellular uptake in tumors. This nanoplatform promoted effective near-infrared light-triggered subcellular hyperthermia treatment in vitro and exhibited excellent tumor ablation ability in vivo. These findings suggested that this multifunctional nanoplatform could significantly enhance the therapeutic efficiency of photothermal therapy based on activated mitochondrial targeting.

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.

Development of a General Fabrication Strategy for Carbonaceous Noble Metal Nanocomposites with Photothermal Property

This study demonstrates a simple hydrothermal method while can be generalized for controllable synthesis of noble metallic carbonaceous nanostructures (e.g., Au@C, Ag@C) under mild conditions (180-200 °C), which also provides a unique approach for fabricating hollow carbonaceous structures by removal of cores (e.g., silver) via a redox etching process. The microstructure and composition of the as-achieved nanoparticles have been characterized using various microscopic and spectroscopic techniques. Cetyltrimethylammonium bromide (CTAB), serving as a surfactant in the reaction system, plays a key role in the formation of Ag@C, Au@C nanocables, and their corresponding hollow carbonaceous nanotubes in this work. The dynamic growth and formation mechanism of carbonaceous nanostructures was discussed in detail. And finally, laser-induced photothermal property of Au@C nanocomposites was examined. The results may be useful for designing and constructing carbonaceous metal(s) or metal oxide(s) nanostructures with potential applications in the areas of electrochemical catalysis, energy storage, adsorbents, and biomedicine. This study demonstrate a facile hydrothermal synthesis of noble metal carbonaceous nanocomposites (e.g., Au@C) with simple procedures under mild conditions, which can be25expanded as a general method for preparing diverse carbonaceous core-shell nanoparticles. The Au@C carbonaceous nanostructures exhibit interesting UV-Vis properties dependent upon shell thickness.

Facile Fabrication of Magnetic Microrobots Based on Spirulina Templates for Targeted Delivery and Synergistic Chemo-Photothermal Therapy

Magnetic microrobots can be actuated in fuel-free conditions and are envisioned for biomedical applications related to targeted delivery and therapy in a minimally invasive manner. However, mass fabrication of microrobots with precise propulsion performance and excellent therapeutic efficacy is still challenging, especially in a predictable and controllable manner. Herein, we propose a facile technique for mass production of magnetic microrobots with multiple functions using Spirulina ( Sp.) as biotemplate. Core-shell-structured Pd@Au nanoparticles (NPs) were synthesized in Sp. cells by electroless deposition, working as photothermal conversion agents. Subsequently, the Fe₃O₄ NPs were deposited onto the surface of the obtained (Pd@Au)@ Sp. particles via a sol-gel process, enabling them to be magnetically actuated. Moreover, the anticancer drug doxorubicin (DOX) was loaded on the (Pd@Au)/Fe₃O₄@ Sp. microrobots, which endows them with additional chemotherapeutic efficacy. The as-prepared biohybrid (Pd@Au)/Fe₃O₄@ Sp.-DOX microrobots not only possess efficient propulsion performance with the highest speed of 526.2 μm/s under a rotating magnetic field but also have enhanced synergistic chemo-photothermal therapeutic efficacy. Furthermore, they can be structurally disassembled into individual particles under near-infrared (NIR) laser irradiation and exhibit pH- and NIR-triggered drug release. These intriguing properties enable the microrobots to be a very promising and efficient platform for drug loading, targeted delivery, and chemo-photothermal therapy.

The Effect of Gold Nanorods Clustering on Near-Infrared Radiation Absorption

In this paper, the plasmonic resonant absorption of gold nanorods (GNRs) and GNR solutions was studied both numerically and experimentally. The heat generation in clustered GNR solutions with various concentrations was measured by exposing them to Near Infrared (NIR) light in experiment. Correspondingly, calculations based on the discrete-dipole approximation (DDA) revealed the same relationship between the maximum absorption efficiency and the nanorod orientation for the incident radiation. Additionally, both the plasmonic wavelength and the maximum absorption efficiency of a single nanorod were found to increase linearly with increasing aspect ratio (for a fixed nanorod volume). The wavelength of the surface plasmonic resonance (SPR) was found to change when the gold nanorods were closely spaced. Specifically, both a shift and a broadening of the resonance peak were attained when the distance between the nanorods was set to about 50 nm or less. The absorbance spectra of suspended nanorods at various volume fractions also showed that the plasmonic wavelength of the nanorods solution was at 780 ± 10 nm, which was in good agreement with the computational predictions for coupled side-by-side nanorods. When heated by NIR light, the rate of increase for both the temperature of solution and the absorbed light diminished when the volume fraction of suspended nanorods reached a value of 1.24×10−6. This matches with expectations for a partially clustered suspension of nanorods in water. Overall, this study reveals that particle clustering should be considered to accurately gauge the heat generation of the GNR hyperthermia treatments.

Magnetic Mesoporous Calcium Sillicate/Chitosan Porous Scaffolds for Enhanced Bone Regeneration and Photothermal-Chemotherapy of Osteosarcoma

The development of multifunctional biomaterials to repair bone defects after neoplasm removal and inhibit tumor recurrence remained huge clinical challenges. Here, we demonstrate a kind of innovative and multifunctional magnetic mesoporous calcium sillicate/chitosan (MCSC) porous scaffolds, made of M-type ferrite particles (SrFe₁₂O₁₉), mesoporous calcium silicate (CaSiO₃) and chitosan (CS), which exert robust anti-tumor and bone regeneration properties. The mesopores in the CaSiO₃ microspheres contributed to the drug delivery property, and the SrFe₁₂O₁₉ particles improved photothermal therapy (PTT) conversion efficacy. With the irradiation of NIR laser, doxorubicin (DOX) was rapidly released from the MCSC/DOX scaffolds. In vitro and in vivo tests demonstrated that the MCSC scaffolds possessed the excellent anti-tumor efficacy via the synergetic effect of DOX drug release and hyperthermia ablation. Moreover, BMP-2/Smad/Runx2 pathway was involved in the MCSC scaffolds promoted proliferation and osteogenic differentiation of human bone marrow stromal cells (hBMSCs). Taken together, the MCSC scaffolds have the ability to promote osteogenesis and enhance synergetic photothermal-chemotherapy against osteosarcoma, indicating MCSC scaffolds may have great application potential for bone tumor-related defects.

NIR-to-NIR Deep Penetrating Nanoplatforms Y2O3:Nd3+/Yb3+@SiO2@Cu2S toward Highly Efficient Photothermal Ablation

A difunctional nano-photothermal therapy (PTT) platform with near-infrared excitation to near-infrared emission (NIR-to-NIR) was constructed through core-shell structures Y₂O₃:Nd³⁺/Yb³⁺@SiO₂@Cu₂S (YRSC), in which the core Y₂O₃:Nd³⁺/Yb³⁺ and shell Cu₂S play the role of bioimaging and photothermal conversion function, respectively. The structure and composition of the present PTT agents (PTAs) were characterized by powder X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectra. The NIR emissions of samples in the biological window area were measured by photoluminescence spectra under the excitation of 808 nm laser; further, the penetration depth of NIR emission at different wavelengths in biological tissue was also demonstrated by comparing with visible (vis) emission from Y₂O₃:Yb³⁺/Er³⁺@SiO₂@Cu₂S and NIR emission from YRSC through different injection depths in pork muscle tissues. The photo-thermal conversion effects were achieved through the outer ultrasmall Cu₂S nanoparticles simultaneously absorb NIR light emission from the core Y₂O₃:Nd^3+/Yb³⁺ and the 808 nm excitation source to generate heat. Further, the heating effect of YRSC nanoparticles was confirmed by thermal imaging and ablation of YRSC to Escherichia coli and human hepatoma (HepG-2) cells. Results indicate that the YRSC has potential applications in PTT and NIR imaging in biological tissue.

Sacrificial-template-free synthesis of core-shell C@Bi2S3 heterostructures for efficient supercapacitor and H2 production applications

Core-shell heterostructures have attracted considerable attention owing to their unique properties and broad range of applications in lithium ion batteries, supercapacitors, and catalysis. Conversely, the effective synthesis of Bi₂S₃ nanorod core@ amorphous carbon shell heterostructure remains an important challenge. In this study, C@Bi₂S₃ core-shell heterostructures with enhanced supercapacitor performance were synthesized via sacrificial- template-free one-pot-synthesis method. The highest specific capacities of the C@Bi₂S₃ core shell was 333.43 F g^-1 at a current density of 1 A g^-1. Core-shell-structured C@Bi₂S₃ exhibits 1.86 times higher photocatalytic H₂ production than the pristine Bi₂S₃ under simulated solar light irradiation. This core-shell feature of C@Bi₂S₃ provides efficient charge separation and transfer owing to the formed heterojunction and a short radial transfer path, thus efficiently diminishing the charge recombination; it also facilitates plenty of active sites for the hydrogen evolution reaction owing to its mesoporous nature. These outcomes will open opportunities for developing low-cost and noble-metal-free efficient electrode materials for water splitting and supercapacitor applications.

Gold nanorods decorated with a cancer drug for multimodal imaging and therapy

Cancer, a condition with uncontrolled cell division, is the second leading cause of death worldwide. The currently available techniques for the imaging and treatment of cancer have their own limitations and hence a combination of more than one modality is expected to increase the efficacy of both diagnosis and treatment. In the present study, we have developed a multimodal imaging and therapeutic system by incorporating a chemotherapeutic drug, mitoxantrone (MTX) onto PEG coated gold nanorods (GNR). Strong absorption in the near-infrared (NIR) and visible regions qualifies GNR as an efficient photothermal (PTT) agent upon irradiation with either a NIR or visible laser. Additionally, the enhanced electric field of GNR makes it a suitable substrate for surface enhanced Raman scattering (SERS). Modification of GNR with amino PEG offers biocompatibility without affecting its optical property. In order to achieve tumor specificity, GNR-PEG was conjugated with tumor specific marker that can target cancer cells, leaving the normal cells unaffected. The incorporation of fluorescent chemotherapeutic drug mitoxantrone onto GNR-PEG facilitates chemotherapy as well as fluorescence imaging. The therapeutic efficacy of the developed GNR based system is tracked using fluorescence imaging and Raman imaging. The careful design of the system also facilitates the controlled release of the drug by photothermal triggering. Likewise, the imaging modality could be chosen as either Raman or fluorescence to monitor drug release in accordance with irradiation. The physico-chemical properties, and drug release profiles under different physiological conditions have been well studied. Finally, the developed system was tested for its therapeutic efficacy using cancer cells, in vitro. The receptor mediated cell uptake was more effective in folate receptor over-expressing cancer cells than in the normal and low-expressing cells. Accordingly the percentage of cell death was higher in folate receptor over-expressing cancer cells, which was further enhanced due to the effect of the dual therapeutic approach. The cell uptake and treatment efficacy was monitored using fluorescence microscopy and SERS. In conclusion, the developed GNR-PEG-MTX system is found to be an efficient multimodal therapeutic agent against cancer which could be tracked using two different techniques.

Photothermal lysis of pathogenic bacteria by platinum nanodots decorated gold nanorods under near infrared irradiation

Photothermal lysis is an effective method for fast removal of pathogenic bacteria from bacterial contaminated environments and human body, irrespective of bacterial drug resistance. In the present work, a highly effective photothermal agent, Au@Pt nanorods (NRs), was prepared by modification of Pt nanodots with particle size of 5nm on the surface of Au NRs with a length of ca. 41nm and a width of ca. 13nm. The LSPR absorbance band of Au@Pt NRs could be tuned from 755 to 845nm by changing the Pt loading from 0.05 to 0.2, as compared to Au NRs. The photothermal conversion efficiency of Au@Pt NRs depended on the Pt loading, Au@Pt NRs concentration, and power density. Under NIR irradiation, the Au@Pt_0.1 NRs exhibited the highest efficiency in photothermal lysis of both gram-positive and gram-negative bacteria. The introduction of Pt nanodots on the surface of Au@Pt NRs not only enhanced their photothermal conversions but also enhanced their affinity to bacteria and significantly decreased their cytotoxicity. The photothermal lysis of bacteria over Au@Pt NRs caused the damage onto the cell walls of bacteria, implying that the killing of bacteria probably went through the thermal ablation mechanism.

A designed synthesis of multifunctional carbon nanoframes for simultaneous imaging and synergistic chemo-photothermal cancer therapy

A simple synthetic route was developed to fabricate mesoporous carbon nanoframes for simultaneous photoacoustic imaging and synergistic chemo-photothermal cancer therapy.

Near-infrared induced phase-shifted ICG/Fe3O4 loaded PLGA nanoparticles for photothermal tumor ablation

Near-infrared (NIR) laser-induced photothermal therapy (PTT) uses a photothermal agent to convert optical energy into thermal energy and has great potential as an effective local, minimally invasive treatment modality for killing cancer cells. To improve the efficacy of PTT, we developed poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) encapsulating superparamagnetic iron oxide (Fe3O4), indocyanine green (ICG), and perfluoropentane (PFP) as synergistic agents for NIR laser-induced PTT. We fabricated a novel type of phase-shifting fluorescent magnetic NPs, Fe3O4/ICG@PLGA/PFP NPs, that effectively produce heat in response to NIR laser irradiation for an enhanced thermal ablation effect and a phase-shift thermoelastic expansion effect, and thus, can be used as a photothermal agent. After in vitro treatment of MCF-7 breast cancer cells with Fe3O4/ICG@PLGA/PFP NPs and NIR laser irradiation, histology and electron microscopy confirmed severe damage to the cells and the formation of many microbubbles with iron particles at the edge or outside of the microbubbles. In vivo experiments in mice with MCF-7 tumors demonstrated that Fe3O4/ICG@PLGA/PFP NPs could achieve tumor ablation upon NIR laser irradiation with minimal toxicity to non-irradiated tissues. Together, our results indicate that Fe3O4/ICG@PLGA/PFP NPs can be used as effective nanotheranostic agents for tumor ablation.

Nuclear-Targeting Gold Nanorods for Extremely Low NIR Activated Photothermal Therapy

Photorelated nanomedicine is of particular interest as an emerging paradigm toward precise cancer therapy, as demonstrated by recent developments of photothermal therapy (PTT), an emerging technique employing light-converting agents to burn cancerous cells by overdosed optical energy-converted heat. However, most of the laser irradiations needed for effective PTT significantly exceed the maximal permissible power density in human skin, which is likely to damage surrounding normal tissues. Herein, we report a strategy of intranuclear PTT of cancer enabled by nuclear-targeted delivery of gold nanorods of ∼10.5 × 40.5 nm in size via conjugation with nuclear location signal peptides (GNRs-NLS) under an extremely low near-infrared irradiation of 0.2 W/cm², much below the maximal permissible exposure of skin. Interestingly, we found that a mild but nuclear-focused temperature increase generated by GNRs-NLS is sufficient to cause damage to intranuclear DNA and the inhibition of DNA repair process, which, interestingly, led to the cancer cell apoptosis rather than to conventional cell necrosis by thermal ablation during PTT. Correspondingly, tumors treated with GNRs-NLS exhibited gradual but significant regressions rather than traditional harsh burning-up of tumors, in comparison with negligible antitumor effect by GNRs without nuclear targeting under the same ultralow NIR irradiation. This report demonstrates the successful intranuclear efficient photothermal therapy of cancer via cell apoptosis by photoadsorbing agents, e.g., GNRs-NLS in the present case, with largely mitigated side-effect on normal tissues and therefore substantially improved biosafety.

Activatable ultrasmall gold nanorods for “off–on” fluorescence imaging-guided photothermal therapy

We developed activatable ultrasmall gold nanorods (AUGNRs) to realize “off–on” switched fluorescence imaging-guided efficient PTT.

Gold-Nanorods-Based Gene Carriers with the Capability of Photoacoustic Imaging and Photothermal Therapy

Multifunctional nanoparticles with high gene transfection activity, low cytotoxicity, photoacoustic imaging ability, and photothermal therapeutic properties were prepared by conjugating low-molecular-weight polyethylenimine onto the surfaces of gold nanorods through the formation of stable S-Au bonded conjugates. Results revealed that the gene transfection efficiency of the prepared polyethylenimine-modified gold nanorods (GNRs-PEI1.8k) was higher and their cytotoxicity was less than those of the commercial reagent PEI25k. GNRs-PEI1.8k could also be potentially used as a photoacoustic and photothermal reagent to evaluate the pharmacokinetics, biodistribution, and antitumor effects of gene/drug nanoparticles. Therefore, GNRs-PEI1.8k can be considered a promising candidate for the clinical diagnosis and treatment of tumors.

Polydopamine-Encapsulated Fe3O4 with an Adsorbed HSP70 Inhibitor for Improved Photothermal Inactivation of Bacteria

Photothermal treatment, a new approach for inactivation of bacteria and pathogens that does not depend on traditional therapeutic approaches, has recently received much attention. In this study, a new type of nanoplatform (PDA@Fe3O4 + PES) was fabricated by using polydopamine (PDA, a photothermal conversion agent) to encapsulate Fe3O4 (a magnetic nanoparticle) and support 2-phenylethynesulfonamide (PES, an inhibitor of heat shock protein 70 (HSP70)). Upon near-infrared light irradiation, the increased temperature weakens π-π and hydrogen bonding interactions, and PES is released from the PDA@Fe3O4 + PES. The released PES inhibits the function of HSP70, reducing bacterial tolerance to photothermal therapy and improving the therapeutic effect against infectious bacterial pathogens. After treatment, PDA@Fe3O4 + PES can be recovered using the magnetic property of the Fe3O4 cores. Consequently, PDA@Fe3O4 + PES possesses the potential to be a recyclable photothermal agent for enhanced photothermal bacterial inactivation without causing secondary pollution.

Glucose-Derived Carbonaceous Nanospheres for Photoacoustic Imaging and Photothermal Therapy

Carbon nanomaterials with small size and unique optical properties have attracted intensive interest for their promising biomedical applications. In this work, glucose-derived carbonaceous nanospheres (CNSs) with high photothermal conversion efficiency up to 35.1% are explored for the first time as a novel carbon-based theranostic agent. Different from most other carbon nanomaterials, the obtained CNSs are highly biocompatible and nontoxic because of their intrinsic hydrophilic property and the use of glucose as raw materials. Under near-infrared laser irradiation (808 nm, 6 W cm(-2)) for 10 min, less than 15% of PC-3M-IE8 cells exposed to CNSs aqueous dispersions (0.16 mg/mL) remained alive. After intravenous administration of CNSs aqueous dispersions into nude mice, the photoacoustic intensity of the tumor region is about 2.5 times higher than that of preinjection. These results indicate that CNSs are suitable for simultaneous photoacoustic imaging and photothermal ablation of cancer cells and can serve as promising biocompatible carbon-based agents for further clinical trials.

Simultaneous tracking of drug molecules and carriers using aptamer-functionalized fluorescent superstable gold nanorod-carbon nanocapsules during thermo-chemotherapy

Controlling and monitoring the drug delivery process is critical to its intended therapeutic function. Many nanocarrier systems for drug delivery have been successfully developed. However, biocompatibility, stability, and simultaneously tracing drugs and nanocarriers present significant limitations. Herein, we have fabricated a multifunctional nanocomposite by coating the gold nanorod (AuNR) with a biocompatible, superstable and fluorescent carbon layer, obtaining the AuNR@carbon core-shell nanocapsule. In this system, the carbon shell, originally obtained in aqueous glucose solutions and, therefore, biocompatible in physiological environments, could be simply loaded with cell-specific aptamers and therapeutic molecules through π-π interactions, a useful tool for cancer-targeted cellular imaging and therapy. Moreover, such a stable and intrinsic fluorescence effect of the AuNR@carbon enabled simultaneous tracking of released therapeutic molecules and nanocarriers under thermo-chemotherapy. The AuNR@carbons had high surface areas and stable shells, as well as unique optical and photothermal properties, making them promising nanostructures for biomedical applications.

Radar-like MoS2 nanoparticles as a highly efficient 808 nm laser-induced photothermal agent for cancer therapy

Radar-like MoS₂ nanoparticles were demonstrated and used as highly efficient photothermal therapy for cancer in vitro and in vivo.

Facile one-pot synthesis of carbon/calcium phosphate/Fe3O4 composite nanoparticles for simultaneous imaging and pH/NIR-responsive drug delivery

We report herein a facile one-pot synthesis of carbon/calcium phosphate/Fe₃O₄ composite nanoparticles, which were employed as pH/NIR-responsive drug delivery vehicles for simultaneous MRI and chemo-photothermal therapy.