Au/polypyrrole@Fe3O4 nanocomposites for MR/CT dual-modal imaging guided-photothermal therapy: an in vitro study

Ligand-Induced Atomically Segregation-Tunable Alloy Nanoprobes for Enhanced Magnetic Resonance Imaging

Bimetallic iron-noble metal alloy nanoparticles have emerged as promising contrast agents for magnetic resonance imaging (MRI) due to their biocompatibility and facile control over the element distribution. However, the inherent surface energy discrepancy between iron and noble metal often leads to Fe atom segregation within the nanoparticle, resulting in limited iron-water molecule interactions and, consequently, diminished relaxometric performance. In this study, we present the development of a class of ligand-induced atomically segregation-tunable alloy nanoprobes (STAN) composed of bimetallic iron-gold nanoparticles. By manipulating the oxidation state of Fe on the particle surface through varying molar ratios of oleic acid and oleylamine ligands, we successfully achieve surface Fe enrichment. Under the application of a 9 T MRI system, the optimized STAN formulation, characterized by a surface Fe content of 60.1 at %, exhibits an impressive r1 value of 2.28 mM-1·s-1, along with a low r2/r1 ratio of 6.2. This exceptional performance allows for the clear visualization of hepatic tumors as small as 0.7 mm in diameter in vivo, highlighting the immense potential of STAN as a next-generation contrast agent for highly sensitive MR imaging.

Hybrid FeWO4-Hyaluronic Acid Nanoparticles as a Targeted Nanotheranostic Agent for Multimodal Imaging-Guided Tumor Photothermal Therapy

Background

Development of versatile nanoplatform still remains a great challenge due to multistep synthesis and complicated compositions. Therefore, it is significant to develop a facile method to synthesize a nanocomposite to achieve multimodal imaging and even imaging-guided cancer therapeutics.

Methods and Results

In our study, hyaluronic acid-functionalized iron (II) tungstate nanoparticles (HA-FeWO4 NPs) were successfully synthesized as a versatile nanoplatform by a facile one-pot hydrothermal procedure. The formed multifunctional HA-FeWO4 NPs were investigated via a series of characterization techniques, which demonstrated good biocompatibility, excellent dispersion, low cytotoxicity, active tumor-targeting ability and high photothermal efficiency. Furthermore, tumor was clearly visualized by HA-FeWO4 NPs with multimodal imaging of infrared thermal imaging, magnetic resonance imaging, computed tomography imaging in 4T1 tumor bearing mice. More importantly, HA-FeWO4 could achieve multimodal imaging-guided photothermal therapy of 4T1 tumors.

Conclusion

The constructed HA-FeWO4 NPs have great potential as ideal nanotheranostic agents for multimodal imaging and even imaging-guided cancer theranostics in biological systems.

3D modeling of in vivo MRI-guided nano-photothermal therapy mediated by magneto-plasmonic nanohybrids

BACKGROUND

Nano-photothermal therapy (NPTT) has gained wide attention in cancer treatment due to its high efficiency and selective treatment strategy. The biggest challenges in the clinical application are the lack of (i) a reliable platform for mapping the thermal dose and (ii) efficient photothermal agents (PTAs). This study developed a 3D treatment planning for NPTT to reduce the uncertainty of treatment procedures, based on our synthesized nanohybrid.

METHODS

This study aimed to develop a three-dimensional finite element method (FEM) model for in vivo NPTT in mice using magneto-plasmonic nanohybrids, which are complex assemblies of superparamagnetic iron oxide nanoparticles and gold nanorods. The model was based on Pennes' bio-heat equation and utilized a geometrically correct mice whole-body. CT26 colon tumor-bearing BALB/c mice were injected with nanohybrids and imaged using MRI (3 Tesla) before and after injection. MR images were segmented, and STereoLithography (STL) files of mice bodies and nanohybrid distribution in the tumor were established to create a realistic geometry for the model. The accuracy of the temperature predictions was validated by using an infrared (IR) camera.

RESULTS

The photothermal conversion efficiency of the nanohybrids was experimentally determined to be approximately 30%. The intratumoral (IT) injection group showed the highest temperature increase, with a maximum of 17 °C observed at the hottest point on the surface of the tumor-bearing mice for 300 s of laser exposure at a power density of 1.4 W/cm². Furthermore, the highest level of tissue damage, with a maximum value of Ω = 0.4, was observed in the IT injection group, as determined through a simulation study.

CONCLUSIONS

Our synthesized nanohybrid shows potential as an effective agent for MRI-guided NPTT. The developed model accurately predicted temperature distributions and tissue damage in the tumor. However, the current temperature validation method, which relies on limited 2D measurements, may be too lenient. Further refinement is necessary to improve validation. Nevertheless, the presented FEM model holds great promise for clinical NPTT treatment planning.

Photonic Hyperthermia Synergizes with Immune-Activators to Augment Tumor-Localized Immunotherapy

Photothermal immunotherapy, the combination of photothermal hyperthermia and immunotherapy, is a noninvasive and desirable therapeutic strategy to address the deficiency of traditional photothermal ablation for tumor treatment. However, insufficient T-cell activation following photothermal treatment is a bottleneck to achieve satisfactory therapeutic effectiveness. In this work, a multifunctional nanoplatform is rationally designed and engineered on the basis of polypyrrole-based magnetic nanomedicine modified by T-cell activators of anti-CD3 and anti-CD28 monoclonal antibodies, which have achieved robust near infrared laser-triggered photothermal ablation and long-lasting T-cell activation, realizing diagnostic imaging-guided immunosuppressive tumor microenvironment regulation following photothermal hyperthermia by reinvigorating tumor-infiltrating lymphocytes. By virtue of high-efficient immunogenic cell death and dendritic cell maturation combined with T-cell activation, this nanosystem markedly restrains primary and abscopal tumors as well as metastatic tumors with negligible side effects in vivo, exerting the specific function for suppressing tumor recurrence and metastasis by establishing a long-term memory immune response.

Colorimetric and photothermal dual-mode lateral flow immunoassay based on Au-Fe3O4 multifunctional nanoparticles for detection of Salmonella typhimurium

Au-Fe₃O₄ multifunctional nanoparticles (NPs) were synthesized and integrated with lateral flow immunoassay (LFIA) for dual-mode detection of Salmonella typhimurium. The Au-Fe₃O₄ NPs not only combined excellent local surface plasmon resonance characteristics and superparamagnetic properties, but also exhibited good photothermal effect. In the detection, antibody-conjugated Au-Fe₃O₄ NPs first captured S. typhimurium from complex matrix, which was then loaded on the LFIA strip and trapped by the T-line. By observing the color bands with the naked eyes, qualitative detection was performed free of instrument. By measuring the photothermal signal, quantification was achieved with a portable infrared thermal camera. The introduction of magnetic separation achieved the enrichment and purification of target bacteria, thus enhancing the detection sensitivity and reducing interference. This dual-mode LFIA achieved a visual detection limit of 5 × 10⁵ CFU/mL and a photothermal detection limit of 5 × 10⁴ CFU/mL. Compared with traditional Au-based LFIA, this dual-mode LFIA increased the detection sensitivity by 2 orders of magnitude and could be directly applied to unprocessed milk sample. Besides, this dual-mode LFIA showed good reproducibility and specificity. The intra-assay and inter-assay variation coefficients were 3.0% and 7.9%, and with this dual-mode LFIA, other bacteria hardly produced distinguishable signals. Thus, the Au-Fe₃O₄ NPs-based LFIA has potential to increase the efficiency of pandemic prevention and control. Au-Fe₃O₄ nanoparticle proved to be a promising alternative reporter for LFIA, achieving multifunctions: target purification, target enrichment, visual qualitation, and instrumental quantification, which improved the limitations of traditional LFIA.

Multifunctional plasmonic-magnetic nanoparticles for bioimaging and hyperthermia

Multicompartment nanoparticles have raised great interest for different biomedical applications, thanks to the combined properties of different materials within a single entity. These hybrid systems have opened new avenues toward diagnosis and combination therapies, thus becoming preferred theranostic agents. When hybrid nanoparticles comprise magnetic and plasmonic components, both magnetic and optical properties can be achieved, which are potentially useful for multimodal bioimaging, hyperthermal therapies and magnetically driven selective delivery. Nanostructures comprising iron oxide and gold are usually selected for biomedical applications, as they display size-dependent properties, biocompatibility, and unique physical and chemical characteristics that can be tuned through highly precise synthetic protocols. We provide herein an overview of the most recent synthetic protocols to prepare magnetic-plasmonic nanostructures made of iron oxide and gold, to then highlight the progress made on multifunctional magnetic-plasmonic bioimaging and heating-based therapies. We discuss the advantages and limitations of the various systems in these directions.

Functionalized Magnetic Nanoparticles for Alternating Magnetic Field- or Near Infrared Light-Induced Cancer Therapies

The multi-faceted nature of functionalized magnetic nanoparticles (fMNPs) is well-suited for cancer therapy. These nanocomposites can also provide a multimodal platform for targeted cancer therapy due to their unique magnetic guidance characteristics. When induced by an alternating magnetic field (AMF), fMNPs can convert the magnetostatic energy to heat for magnetic hyperthermia (MHT), as well as for controlled drug release. Furthermore, with the ability to convert near-infrared (NIR) light energy to heat energy, fMNPs have attracted interest for photothermal therapy (PTT). Other than MHT and PTT, fMNPs also have a place in combination cancer therapies, such as chemo-MHT, chemo-PTT, and chemo-PTT-photodynamic therapy, among others, due to their versatile properties. Thus, this review presents multifunctional nanocomposites based on fMNPs for cancer therapies, induced by an AMF or NIR light. We will first discuss the different fMNPs induced with an AMF for cancer MHT and chemo-MHT. Secondly, we will discuss fMNPs irradiated with NIR lasers for cancer PTT and chemo-PTT. Finally, fMNPs used for dual-mode AMF + NIR-laser-induced magneto-photo-hyperthermia (MPHT) will be discussed.

Advances of functional nanomaterials for magnetic resonance imaging and biomedical engineering applications

Functional nanomaterials have been widely used in biomedical fields due to their good biocompatibility, excellent physicochemical properties, easy surface modification, and easy regulation of size and morphology. Functional nanomaterials for magnetic resonance imaging (MRI) can target specific sites in vivo and more easily detect disease-related specific biomarkers at the molecular and cellular levels than traditional contrast agents, achieving a broad application prospect in MRI. This review focuses on the basic principles of MRI, the classification, synthesis and surface modification methods of contrast agents, and their clinical applications to provide guidance for designing novel contrast agents and optimizing the contrast effect. Furthermore, the latest biomedical advances of functional nanomaterials in medical diagnosis and disease detection, disease treatment, the combination of diagnosis and treatment (theranostics), multi-model imaging and nanozyme are also summarized and discussed. Finally, the bright application prospects of functional nanomaterials in biomedicine are emphasized and the urgent need to achieve significant breakthroughs in the industrial transformation and the clinical translation is proposed. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Diagnostic Nanodevices Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Recent Advances of Magnetic Gold Hybrids and Nanocomposites, and Their Potential Biological Applications

Magnetic gold nanoparticles (mGNP) have become a great interest of research for nanomaterial scientists because of their significant magnetic and plasmonic properties applicable in biomedical applications. Various synthetic approaches and surface modification techniques have been used for mGNP including the most common being the coprecipitation, thermal decomposition, and microemulsion methods in addition to the Brust Schiffrin technique, which involves the reduction of metal precursors in a two-phase system (water and toluene) in the presence of alkanethiol. The hybrid magnetic–plasmonic nanoparticles based on iron core and gold shell are being considered as potential theranostic agents. In this critical review, in addition to future works, we have summarized recent developments for synthesis and surface modification of mGNP with their applications in modern biomedical science such as drug and gene delivery, bioimaging, biosensing, and neuro-regeneration, neuro-degenerative and arthritic disorders. This review includes techniques and biological applications of mGNP majorly based on research from the previous six years.

Flexible and Effective Preparation of Magnetic Nanoclusters via One-Step Flow Synthesis

Fe3O4 nanoclusters have attractive applications in various areas, due to their outstanding superparamagnetism. In this work, we realized a one-step flow synthesis of Fe3O4 nanoclusters, within minutes, through the sequential and quantitative introduction of reactants and modifier in a microflow system. The enhanced micromixing performance enabled a prompt and uniform supply of the modifier oleic acid (OA) for both nanoparticle modification and nanocluster stabilization to avoid uncontrolled modified nanoparticles aggregation. The size of the nanoclusters could be flexibly tailored in the range of 50–100 nm by adjusting the amount of OA, the pH, and the temperature. This rapid method proved the possibility of large-scale and stable production of magnetic nanoclusters and provided convenience for their applications in broad fields.

Synthesis of manganese-oxide and palladium nanoparticles co-decorated polypyrrole/graphene oxide (MnO2@Pd@PPy/GO) nanocomposites for anti-cancer treatment

Design and fabrication of novel multifunctional nanomaterials as novel “theranostic nanoagents”with high efficiency and low side effects is important for cancer treatment. Herein, we synthesized manganese-oxide and palladium nanoparticle-co-decorated polypyrrole/graphene oxide (MnO₂@Pd@PPy/GO) nanocomposites, which could be used as a novel “theranostic nanoagent” for cancer treatment. Various spectroscopic and microscopic characterizations of the synthesized MnO₂@Pd@PPy/GO nanocomposites suggest that the nanocomposites are assembled sequentially by graphene oxide, polypyrrole, palladium nanoparticles and manganese-oxide nanoplates. Further research revealed that the nanocomposites had excellent photothermal conversion performance (reached near 50 °C after 10 min of irradiation), pH responsive enzymatic-like catalytic activity and enhanced magnetic resonance imaging (MRI) performance (r₁ = 7.74 mM⁻¹ s⁻¹ at pH 5.0 and glutathione (GSH)). Cell experiments also testified that combined cancer treatment (the viability of cancer cells is 30%) with photothermal therapy (PTT, the viability of cancer cells is 91% only with irradiation) and chemodynamic therapy (CDT, the viability of cancer cells is 74.7% only with nanocomposites) guided by MRI was achieved when the as-prepared nanocomposites were employed as theranostic nanoagents. This work could provide some new ideas for the controllable synthesis and application of multicomponent nanomaterials.

Manganese-oxide and palladium nanoparticle-co-decorated polypyrrole/graphene oxide (MnO₂@Pd@PPy/GO) nanoenzyme composites were synthesized, and could be as a novel “theranostic nanoagent” for cancer treatment due to excellent performance.

Glucose/Glutathione Co-triggered Tumor Hypoxia Relief and Chemodynamic Therapy to Enhance Photothermal Therapy in Bladder Cancer

Photothermal therapy (PTT) is a potential treatment for cancer that makes use of near-infrared (NIR) laser irradiation and is expected to assist traditional anti-cancer drug therapies; however, the therapeutic efficacy of PTT is restricted by thermal resistance due to the overexpression of heat shock proteins and insufficient penetration depth of lasers. Thus, PTT needs to be combined with additional therapeutic methods to obtain the optimal therapeutic efficacy for cancer. Herein, a multifunctional therapeutic platform combining PTT with glucose-triggered chemodynamic therapy (CDT) and glutathione (GSH)-triggered hypoxia relief was developed via GOx@MBSA-PPy-MnO₂ NPs (GOx for glucose oxidase, M for Fe₃O₄, BSA for bovine serum albumin, and PPy for polypyrrole). GOx@MBSA-PPy-MnO₂ NPs have excellent photothermal efficiency and can release Mn²⁺, which catalyzes the transformation of H₂O₂ into hydroxyl radicals (·OH) and O₂ via a Fenton-like reaction, effectively destroying cancer cells and relieving tumor hypoxia. Meanwhile, a high content of H₂O₂ was produced via GOx catalysis of glucose, further enhancing the CDT efficiency. In addition, in vitro and in vivo experiments showed that the inhibition of cancer cell proliferation and effective inhibition of tumors could be caused by the combined PTT/glucose-triggered CDT effects and hypoxia relief of the GOx@MBSA-PPy-MnO₂ NPs. Overall, this work provides evidence of a synergistic therapy that remarkably improves therapeutic efficacy and significantly prolongs the lifetime of mice compared with controls.

Fenton Reaction Induced by Fe-Based Nanoparticles for Tumor Therapy

Fenton reaction, a typical inorganic reaction, is broadly utilized in the field of wastewater treatment. Recently In case of its ability to inhibit the growth of cancer cells, it has been frequently reported in cancer treatment. Using the unique tumor microenvironment in cancer cells, many iron-based nanoparticles have been developed to release iron ions in cancer cells to induce Fenton reaction. In this mini review, we outline several different types of iron-based nanoparticles and several main means to enhance Fenton reaction in cancer cells. Finally, we discussed the advantages and disadvantages of iron-based nanoparticles for cancer therapy, prospected the future development of iron-based nanoparticles. It is believed that iron-based nanoparticles can make certain contribution to the cause of human cancer in the future.

Targeted Photothermal Therapy of Melanoma in C57BL/6 Mice using Fe3O4@Au Core-shell Nanoparticles and Near-infrared Laser

BACKGROUND

Gold nanoshells can be tuned to absorb a particular wavelength of light. As a result, these tunable nanoparticles (NPs) can efficiently absorb light and convert it to heat. This phenomenon can be used for cancer treatment known as photothermal therapy. In this study, we synthesized Fe₃O₄@Au core-shell NPs, magnetically targeted them towards tumor, and used them for photothermal therapy of cancer.

OBJECTIVE

The main purpose of this research was to synthesize Fe₃O₄@Au core-shell NPs, magnetically target them towards tumor, and use them for photothermal therapy of cancer.

MATERIAL AND METHODS

In this experimental study, twenty mice received 2 × 10⁶ B16-F10 melanoma cells subcutaneously. After tumors volume reached 100 mm³, the mice were divided into five groups including a control group, NPs group, laser irradiation group, NPs + laser group and NPs + magnet + laser group. NPs were injected intravenously. After 6 hours, the tumor region was irradiated by laser (808 nm, 2.5 W/cm², 6 minutes). The tumor volumes were measured every other day.

RESULTS

The effective diameter of Fe₃O₄@Au NPs was approximately 37.8 nm. The average tumor volume in control group, NPs group, laser irradiation group, NPs + laser irradiation group and NPs + magnet + laser irradiation group increased to 47.3, 45.3, 32.8, 19.9 and 7.7 times, respectively in 2 weeks. No obvious change in the average body weight for different groups occurred.

CONCLUSION

Results demonstrated that magnetically targeted nano-photothermal therapy of cancer described in this paper holds great promise for the selective destruction of tumors.

HA targeted-biodegradable nanocomposites responsive to endogenous and exogenous stimulation for multimodal imaging and chemo-/photothermal therapy

Multimodal imaging-guided accurate tumor-targeting and efficient synergistic therapy are of great importance for cancer therapy in vitro and in vivo. In this study, a biocompatible, tumor-targeted, on-demand chemo-/photothermal therapeutic nanoplatform (HIDSiGdNPs@PDA-HA) based on hollow mesoporous organic silica nanoparticles (HMONs) was used for bimodal imaging and multi-factor stepwise response for drug release and treatment. Targeted molecule hyaluronic acid (HA) promoted the endocytosis of HIDSiGdNPs@PDA-HA in HeLa cancer cells. The gatekeeper pH-/light-sensitive PDA coating was stimulated by the endogenous tumor acidic microenvironment and exogenous NIR laser to release doxorubicin (DOX). Thereafter, HMONs containing S-S bonds were reduced and degraded by endogenous glutathione (GSH), and the drug was further released rapidly to kill cancer cells. Importantly, the photothermal reagent indocyanine green (ICG) was always retained in the carrier, improving the effectiveness of photothermal therapy. The loaded Gd-doped silicon nanoparticles (SiGdNPs) combined with DOX and ICG led to multi-color fluorescence imaging in vitro and magnetic resonance imaging in vivo to realize targeted diagnosis and track drug distribution. The treatment results of tumor-bearing mice also proved the excellent synergistic therapy. It is believed that the multifunctional nanomaterials with dual mode imaging capability and targeted and controlled collaborative therapy would provide an alternative for accurate diagnosis and efficient treatment.

A multifunctional dual-shell magnetic nanocomposite with near-infrared light response for synergistic chemo-thermal tumor therapy

The synergistic tumor therapy in single nanoplatform has always been the goal for high efficacy tumor treatment while still remains great challenge. This paper reports a versatile nanotheranostic platform enlisting magnetic iron oxide nanoparticles, polydopamine (PDA), gold nanocages (Au nanocage) and metal organic framework (MOF, MIL101-NH₂ ) in order to achieve synergistic chemothermal tumor therapy both in vitro and in vivo. The prepared magnetic photothermal nanoparticles (MPNPs) exhibit high drug loading capacity (31.34 mg/g), superior photo-thermal capacity (11.5°C enhancement in 180 s), low bio-toxicity, good magnetic resonance with a low dosage of 22 μg/g, as well as high antitumor efficacy in vivo. Such a novel and multifunctional nanoplatform is expected to find promising applications in target tumor synergistic therapy.

A Hybrid Organo-Nanotheranostic Platform of Superlative Biocompatibility for Near-Infrared-Triggered Fluorescence Imaging and Synergistically Enhanced Ablation of Tumors

The quest for an all-organic nanosystem with negligible cytotoxicity and remarkable in vivo tumor theranostic capability is inescapably unending. Hitherto, the landscape of available photothermal agents is dominated by metal-based nanoparticles (NPs) with attendant in vivo negatives. Here, an all-organic-composed theranostic nanosystem with outstanding biocompatibility for fluorescence image-guided tumor photothermal therapy, and as a potential alternative to metal-based photothermal agents is developed. This is rationally achieved by compartmentalizing indocyanine green (ICG) in glycol chitosan (GC)-polypyrrole (PP) nanocarrier to form hybrid ICG@GC-PP NPs (≈65 nm). The compartmentalization strategy, alongside the high photothermal conversion ability of PP jointly enhances the low photostability of free ICG. Advantageously, ICG@GC-PP is endowed with an impeccable in vivo performance by the well-known biocompatibility track records of its individual tri organo-components (GC, PP, and ICG). As a proof of concept, ICG@GC-PP NPs enables a sufficiently prolonged tumor diagnosis by fluorescence imaging up to 20 h post-injection. Furthermore, owing to the complementary heating performances of PP and ICG, ICG@GC-PP NPs-treated mice by one-time near-infrared irradiation exhibit total tumor regression within 14 days post-treatment. Therefore, leveraging the underlying benefits of this study will help to guide the development of new all-organic biocompatible systems in synergism, for safer tumor theranostics.

Persistent luminescence-polypyrrole nanocomposite for dual-modal imaging and photothermal therapy of mammary cancer

Multifunctional nanocomposites that possess imaging and high-performance therapeutic features are experiencing a surge in interest in the precision clinical anticancer treatment. In this work, we reported the fabrication and bio-application of a novel persistent luminescence-polypyrrole nanocomposite (LPLNP@SPP) for photoacoustic/persistent luminescence (PA/PL) dual-modal imaging guided photothermal therapy (PTT). The construction of LPLNP@SPP avoids the PL quenching of LPLNP-OH by the polypyrrole-coating, and thus enables the combination of PL and PTT. The LPLNP@SPP shows excellent biocompatibility, long lasting near-infrared (NIR) PL emitting without in situ excitation and high-contrast PA signals. Meanwhile, this nanocomposite exhibits strong NIR absorbance and exceptional photothermal conversion capability, which provides notable potential for imaging-guided antitumor therapy. Thus, our work highlights the dual-functional core-shell LPLNP@SPP as a feasible theranostic nanoplatform for cancer diagnosis and therapy.

Janus Magnetic-Plasmonic Nanoparticles for Magnetically Guided and Thermally Activated Cancer Therapy

Progress of thermal tumor therapies and their translation into clinical practice are limited by insufficient nanoparticle concentration to release therapeutic heating at the tumor site after systemic administration. Herein, the use of Janus magneto-plasmonic nanoparticles, made of gold nanostars and iron oxide nanospheres, as efficient therapeutic nanoheaters whose on-site delivery can be improved by magnetic targeting, is proposed. Single and combined magneto- and photo-thermal heating properties of Janus nanoparticles render them as compelling heating elements, depending on the nanoparticle dose, magnetic lobe size, and milieu conditions. In cancer cells, a much more effective effect is observed for photothermia compared to magnetic hyperthermia, while combination of the two modalities into a magneto-photothermal treatment results in a synergistic cytotoxic effect in vitro. The high potential of the Janus nanoparticles for magnetic guiding confirms them to be excellent nanostructures for in vivo magnetically enhanced photothermal therapy, leading to efficient tumor growth inhibition.

Thermocouple-tip-exposing temperature assessment technique for evaluating photothermal conversion efficiency of plasmonic nanoparticles at low laser power density

A new thermocouple (TC) tip-exposing temperature assessment technique that combines experimental temperature measurements with a numerical model of the photothermal conversion efficiency η is presented. The proposed technique is designed to evaluate η for a gold-coated superparamagnetic iron oxide nanoparticle (SPIO-Au NP) solution (26 nm, 12-70 ppm) at low continuous wave laser power (103 mW, 532 nm) irradiation in a convenient manner under ambient conditions. The TC tip temperature is measured during the first 30 s of the laser exposure, and the results are combined with a finite element model to simulate the temperature rise of the NP solution for a given concentration. The value of η is adjusted in the model until the model agrees with the measured transient TC temperature rise. Values of η = 1.00 were observed for all concentrations. Theoretical predictions of η derived by Mie theory confirmed the near unity conversion efficiency of the as-synthesized SPIO-Au NPs. Advantages of the current technique include co-locating the TC tip in the geometric center of the laser-heated region, rather than outside of this region. In addition, the technique can be done under ambient room conditions using unmodified commercially available hardware.

Loading Graphene Quantum Dots into Optical-Magneto Nanoparticles for Real-Time Tracking In Vivo

Fluorescence imaging offers a new approach to visualize real-time details on a cellular level in vitro and in vivo without radioactive damage. Poor light stability of organic fluorescent dyes makes long-term imaging difficult. Due to their outstanding optical properties and unique structural features, graphene quantum dots (GQDs) are promising in the field of imaging for real-time tracking in vivo. At present, GQDs are mainly loaded on the surface of nanoparticles. In this study, we developed an efficient and convenient one-pot method to load GQDs into nanoparticles, leading to longer metabolic processes in blood and increased delivery of GQDs to tumors. Optical-magneto ferroferric oxide@polypyrrole (Fe3O4@PPy) core-shell nanoparticles were chosen for their potential use in cancer therapy. The in vivo results demonstrated that by loading GQDs, it was possible to monitor the distribution and metabolism of nanoparticles. This study provided new insights into the application of GQDs in long-term in vivo real-time tracking.

Organic Nanotheranostics for Photoacoustic Imaging-Guided Phototherapy

Phototherapies including photothermal therapy (PTT) and photodynamic therapy (PDT) have emerged as one of the avant-garde strategies for cancer treatment. Photoacoustic (PA) imaging is a new hybrid imaging modality that shows great promise for real-time in vivo monitoring of biological processes with deep tissue penetration and high spatial resolution. To enhance therapeutic efficacy, reduce side effects and minimize the probability of over-medication, it is necessary to use imaging and diagnostic methods to identify the ideal therapeutic window and track the therapeutic outcome. With this regard, nanotheranostics with the ability to conduct PA imaging and PTT/PDT are emerging. This review summarizes the recent progress of organic nanomaterials including nearinfrared (NIR) dyes and semiconducting polymer nanoparticles (SPNs) in PA imaging guided cancer phototherapy, and also addresses their present challenges and potential in clinical applications.

MSOT/CT/MR imaging-guided and hypoxia-maneuvered oxygen self-supply radiotherapy based on one-pot MnO2-mSiO2@Au nanoparticles

Radiotherapy (RT) is one of the most widely applied treatments for cancer therapy in clinics. Herein, we constructed innovative multifunctional nanotheranostic MnO2-mSiO2@Au-HA nanoparticles (MAHNPs) based on one-pot MnO2-mSiO2 nanohybrids (MNHs) and gold nanoparticles (AuNPs) for multispectral optoacoustic tomography (MSOT)/computed tomography (CT) and magnetic resonance (MR) imaging-guided hypoxia-maneuvered radiotherapy. The MNHs were prepared via a facile one-pot approach, which avoided the leakage of MnO2 nanoparticles and increased the synthetic efficiency. The Mn2+ ions triggered the breakdown of endogenous H2O2 to generate O2 to convert the hypoxic tumor micro-environment (TME), thus enhancing radiotherapy by self-supply oxygen. In addition, hyaluronic acid (HA) was employed to modify the surface of the MnO2-mSiO2@Au nanoparticles to improve their biocompatibility and cellular uptake. The well-designed nanoparticles could perform remarkable photothermal therapy (PTT) and hypoxia-maneuvered radiotherapy (RT) simultaneously and MSOT/CT/MR imaging. The in vivo studies showed that the MAHNPs achieved almost total suppression of tumor growth without observable recurrence, which raises new possibilities for clinical nanotheranostics with multimodal diagnostic and therapeutic coalescent design.

Evaluation of X-ray tomography contrast agents: A review of production, protocols, and biological applications

X-ray computed tomography is a strong tool that finds many applications both in medical applications and in the investigation of biological and nonbiological samples. In the clinics, X-ray tomography is widely used for diagnostic purposes whose three-dimensional imaging in high resolution helps physicians to obtain detailed image of investigated regions. Researchers in biological sciences and engineering use X-ray tomography because it is a nondestructive method to assess the structure of their samples. In both medical and biological applications, visualization of soft tissues and structures requires special treatment, in which special contrast agents are used. In this detailed report, molecule-based and nanoparticle-based contrast agents used in biological applications to enhance the image quality were compiled and reported. Special contrast agent applications and protocols to enhance the contrast for the biological applications and works to develop nanoparticle contrast agents to enhance the contrast for targeted drug delivery and general imaging applications were also assessed and listed.

Rodlike MSN@Au Nanohybrid-Modified Supermolecular Photosensitizer for NIRF/MSOT/CT/MR Quadmodal Imaging-Guided Photothermal/Photodynamic Cancer Therapy

Recently, rodlike nanomaterials with specific aspect ratio for efficient cellular uptake have received enormous attention. For functional nanomaterials, such as photothermal agents, large surface areas for their rod-shaped exterior that increase the amount of light absorbed would lead to a higher absorption coefficient as well as drug-loading property. In this project, we coated rodlike mesoporous silica with gold nanoshells (MSNR@Au hybrid), modifying them with ultrasmall gadolinium (Gd)-chelated supramolecular photosensitizers, TPPS₄ (MSNR@Au-TPPS₄(Gd)), which could be applied to near-infrared fluorescence/multispectral optoacoustic tomography/computed tomography/magnetic resonance imaging and imaging-guided remotely controlled photothermal (PTT)/photodynamic (PDT) combined antitumor therapy. Gold nanoshells, as a perfect PTT agent, were used to assemble the rodlike mesoporous silica nanoparticles with larger superficial area and higher drug loading, thus obtaining the MSNR@Au hybrid. HS-β-CD, which was used as the host, was adsorbed on the gold nanoshell (MSNR@Au-β-CD) to link TPPS₄(Gd) through the host-guest reaction, thus forming CD-TPPS₄ supramolecular photosensitizers (supraPSs). Compared with conventional PSs, supraPSs have host screens, which could reduce the self-aggregation of TPPS₄, and consequently generate ¹O₂ with high efficiency. The in vivo quadmodal imaging of MSNR@Au-TPPS₄(Gd) nanoparticles revealed an intensive tumor uptake effect after injection. The in vivo antitumor efficacy further testified that the synergistic therapy, which was more efficient than any other monotherapy, exhibited an excellent tumor inhibition therapeutic effect. As a result, this encourages to further explore multifunctional theranostic nanoparticles based on gold shells for combined cancer therapy.

Nanocatalysts-Augmented and Photothermal-Enhanced Tumor-Specific Sequential Nanocatalytic Therapy in Both NIR-I and NIR-II Biowindows

The tumor microenvironment (TME) has been increasingly recognized as a crucial contributor to tumorigenesis. Based on the unique TME for achieving tumor-specific therapy, here a novel concept of photothermal-enhanced sequential nanocatalytic therapy in both NIR-I and NIR-II biowindows is proposed, which innovatively changes the condition of nanocatalytic Fenton reaction for production of highly efficient hydroxyl radicals (•OH) and consequently suppressing the tumor growth. Evidence suggests that glucose plays a vital role in powering cancer progression. Encouraged by the oxidation of glucose to gluconic acid and H₂ O₂ by glucose oxidase (GOD), an Fe₃ O₄ /GOD-functionalized polypyrrole (PPy)-based composite nanocatalyst is constructed to achieve diagnostic imaging-guided, photothermal-enhanced, and TME-specific sequential nanocatalytic tumor therapy. The consumption of intratumoral glucose by GOD leads to the in situ elevation of the H₂ O₂ level, and the integrated Fe₃ O₄ component then catalyzes H₂ O₂ into highly toxic •OH to efficiently induce cancer-cell death. Importantly, the high photothermal-conversion efficiency (66.4% in NIR-II biowindow) of the PPy component elevates the local tumor temperature in both NIR-I and NIR-II biowindows to substaintially accelerate and improve the nanocatalytic disproportionation degree of H₂ O₂ for enhancing the nanocatalytic-therapeutic efficacy, which successfully achieves a remarkable synergistic anticancer outcome with minimal side effects.

Magnetic-Plasmonic Heterodimer Nanoparticles: Designing Contemporarily Features for Emerging Biomedical Diagnosis and Treatments

Magnetic-plasmonic heterodimer nanostructures synergistically present excellent magnetic and plasmonic characteristics in a unique platform as a multipurpose medium for recently invented biomedical applications, such as magnetic hyperthermia, photothermal therapy, drug delivery, bioimaging, and biosensing. In this review, we briefly outline the less-known aspects of heterodimers, including electronic composition, interfacial morphology, critical properties, and present concrete examples of recent progress in synthesis and applications. With a focus on emerging features and performance of heterodimers in biomedical applications, this review provides a comprehensive perspective of novel achievements and suggests a fruitful framework for future research.

Folic acid-conjugated gold nanorod@polypyrrole@Fe3O4 nanocomposites for targeted MR/CT/PA multimodal imaging and chemo-photothermal therapy

Integrating multimodal bioimaging and different therapies into one nanoplatform is a promising strategy for biomedical applications, but remains a great challenge. Herein, we have synthesized a biocompatible folic acid (FA) functionalized gold nanorod@polypyrrole@Fe₃O₄ (GNR@PPy@Fe₃O₄-FA) nanocomposite through a facile method. The conjugated FA has endowed the nanocomposite with the ability to recognize targeted cancer cells. Importantly, the nanocomposite has been successfully utilized for magnetic resonance (MR), computed tomography (CT) and photoacoustic (PA) multimodal imaging. Moreover, the GNR@PPy@Fe₃O₄-DOX nanocomposite shows pH-responsive chemotherapy and enables the integration of photothermal therapy and chemotherapy to achieve superior antitumor efficacy. The GNR@PPy@Fe₃O₄-DOX nanocomposites have a drug release of 23.64%, and the photothermal efficiency of the GNR@PPy@Fe₃O₄ nanocomposites reaches 51.46%. Cell viability decreases to 15.83% and 16.47% because of the combination of chemo-photothermal therapy effects. Moreover, the GNR@PPy@Fe₃O₄-DOX-FA nanocomposite could target cancer cells via folic acid and under a magnetic field. The in vivo multimodal imaging and chemo-photothermal therapy effects showed that the GNR@PPy@Fe₃O₄-DOX-FA nanocomposites are a good contrast and theranostic agent. Thus, this multifunctional nanocomposite could be a promising theranostic platform for cancer diagnosis and therapy.

Folic acid-conjugated gold nanorod@polypyrrole@Fe₃O₄ nanocomposites can be used for targeted MR/CT/PA multimodal imaging and chemo-photothermal therapy.

Facile Preparation of Gold-Decorated Fe₃O₄ Nanoparticles for CT and MR Dual-Modal Imaging

The development of a multifunctional nanoprobe capable of non-invasive multimodal imaging is crucial for precise tumour diagnosis. Herein, we report a facile polymer-assisted method to produce Au-Fe₃O₄ nanocomposites (NCPs) for the dual-modal magnetic resonance (MR) and X-ray computed tomography (CT) imaging of tumours. In this approach, amino-functionalized Au nanospheres were first obtained by surface modification of the bifunctional polymer SH-PEG-NH₂. Hydrophilic and carboxyl-functionalized Fe₃O₄ nanoparticles were produced by phase transfer of reverse micelle oxidation in our previous work. The Au nanoparticles were conjugated with hydrophilic Fe₃O₄ nanoparticles through an amide reaction. The obtained Au-Fe₃O₄ nanocomposites display a high r₂ relativity (157.92 mM⁻¹ s⁻¹) and a Hounsfield units (HU) value (270 HU) at Au concentration of 8 mg/mL and could be applied as nanoprobes for the dual-modal MR/CT imaging of a xenografted tumour model. Our work provides a facile method to prepare Au-Fe₃O₄ nanocomposites for dual-modal MR/CT imaging, and this method can be extended to prepare other multifunctional nanoparticles for multimodal bioimaging.

Metal-Organic Framework as a Microreactor for in Situ Fabrication of Multifunctional Nanocomposites for Photothermal-Chemotherapy of Tumors in Vivo

Metal-organic frameworks (MOFs) have been applied in chemotherapeutic drug loading for cancer treatment, but challenging for cases with large and malignant lesions. To overcome these difficulties, combinational therapies of chemotherapy and photothermal therapy (PTT) with potentially high selectivity and slight aggressiveness have drawn tremendous attention to treat various tumors. However, current MOF-based nanohybrids with photothermal agents involve tedious synthesis processes and heterogeneous structures. Herein, we employ MIL-53 as a microreactor to grow polypyrrole (PPy) nanoparticles in situ for the fabrication of PPy@MIL-53 nanocomposites. Fe³⁺ in MIL-53, as an intrinsic oxidizing agent, can oxidize the pyrrole monomer to generate PPy nanoparticles. The prepared PPy@MIL-53 nanocomposites integrate the intrinsic advantages of MOFs with high drug loading ability and magnetic resonance imaging (MRI) capacity, and PPy nanoparticles with outstanding PTT ability and excellent biocompatibility. The versatile PPy@MIL-53 nanocomposites with multiple functions displayed in vitro and in vivo synergism of photothermal-chemotherapy for cancer, potentially MRI-guided. The proposed MOF microreactor-based synthesis strategy shows a promising prospect in the fabrication of diverse multifunctional nanohybrids for tumor theranostics in vivo.

One-Step Synthesis of Iodinated Polypyrrole Nanoparticles for CT Imaging Guided Photothermal Therapy of Tumors

Theranostic materials are of great significance to a personalized precise medicine. However, conventional theranostic agents are mainly fabricated by combining presynthesized independent imaging probes and therapeutic agents, suffering from multiple synthesis procedures, poor morphological control, and time/reagent-consuming process. Herein, iodinated polypyrrole (I-PPy) nanoparticles are fabricated via a one-step synthesis strategy combining chemical oxidation and iodination for computed tomography (CT) imaging-guided photothermal therapy. Iodic acid with a high standard electrode potential enables the chemical oxidation polymerization of pyrrole monomers. Meanwhile, the iodination of PPy induced by the corresponding reduction product I₂ takes place during the polymerization process to generate I-PPy nanoparticles. The prepared I-PPy nanoparticles possess a uniform size, excellent colloidal stability, intense near-infrared absorption, strong X-ray attenuation ability, and favorable biocompatibility. The as-synthesized I-PPy nanoparticles not only guarantee remarkable contrast-enhanced CT imaging of blood pool and tumors, but also realize effective tumor suppression in vitro and in vivo by I-PPy nanoparticles-mediated CT imaging-guided photothermal therapy. To the best of the authors' knowledge, it is the first time that multifunctional PPy nanoparticles are fabricated through a one-step synthesis process. The proposed strategy opens up a new way for the fabrication of high-performance theranostic agents via a one-step strategy under mild conditions.

Gadolinium-doped hollow CeO2-ZrO2 nanoplatform as multifunctional MRI/CT dual-modal imaging agent and drug delivery vehicle

Developing multifunctional nanoparticle-based theranostic platform for cancer diagnosis and treatment is highly desirable, however, most of the present theranostic platforms are fabricated via complicated structure/composition design and time-consuming synthesis procedures. Herein, the multifunctional Gd/CeO2-ZrO2/DOX-PEG nanoplatform with single nano-structure was fabricated through a facile route, which possessed MR/CT dual-model imaging and chemotherapy ability. The nanoplatform not only exhibited well-defined shapes, tunable compositions and narrow size distributions, but also presented a well anti-cancer effect and MR/CT imaging ability. Therefore, the Gd/CeO2-ZrO2/DOX-PEG nanoplatform could be applied for chemotherapy as well as dual-model MR/CT imaging.