Gold nanorod@silica-carbon dots as multifunctional phototheranostics for fluorescence and photoacoustic imaging-guided synergistic photodynamic/photothermal therapy

Upconverting Carbon Nanodots from Ethylenediaminetetraacetic Acid (EDTA) as Near-Infrared Activated Phototheranostic Agents

This work describes the synthesis of nitrogen-doped carbon nanodots (CNDs) synthesized from ethylenediaminetetraacetic acid (EDTA) as a precursor and their application as luminescent agents with a dual-mode theranostic role as near-infrared (NIR) triggered imaging and photodynamic therapy agents. Interestingly, these fluorescent CNDs are more rapidly and selectively internalized by tumor cells and exhibit very limited cytotoxicity until remotely activated with a NIR illumination source. These CNDs are excellent candidates for phototheranostic purposes, for example, simultaneous imaging and therapy can be carried out on cancer cells by using their luminescent properties and the in situ generation of reactive oxidative species (ROS) upon excitation in the NIR range. In the presence of CNDs, NIR remote activation induces the in vitro killing of U251MG cells. Through the use of flow imaging cytometry, we have been able to successfully map and quantify the different types of cell deaths induced by the presence of intracellular superoxide anions (^. O₂ ^- ) and hydrogen peroxide (H₂ O₂ ) ROS generated in situ upon NIR irradiation.

In situ aqueous synthesis of genetically engineered polypeptide-capped Ag2S quantum dots for second near-infrared fluorescence/photoacoustic imaging and photothermal therapy

Ag₂S quantum dots have received extensive attention as theranostic agents for second near-infrared (NIR-II) fluorescence and photoacoustic dual-mode imaging, and photothermal therapy. However, it is still greatly challenging to synthesize Ag₂S quantum dots using aqueous synthesis. In this study, genetically engineered polypeptide-capped Ag₂S quantum dots were successfully synthesized. Three cysteines were integrated to the C-terminal and N-terminal of RGDPC₁₀A to enhance the stability and brightness of the synthesized Ag₂S quantum dots. The RGDPC₁₀A-capped Ag₂S quantum dots exhibited excellent stability, outstanding resistance to photobleaching, and a superior quantum yield of up to 3.78% in the NIR-II biological window. The in vitro and in vivo results showed that the RGDPC₁₀A-capped Ag₂S quantum dots possessed typical NIR-II fluorescence, photoacoustic imaging, and photothermal therapeutic effectiveness against tumors. Moreover, the results of toxicity assays suggested that the RGDPC₁₀A-capped Ag₂S quantum dots have negligible long-term toxicity. These findings open up the possibility for synthesizing theranostic agents by using this aqueous method.

Thieno[3,2-b]thiophene-DPP based near-infrared nanotheranostic agent for dual imaging-guided photothermal/photodynamic synergistic therapy

Diketopyrrolopyrrole (DPP) based organic molecules have drawn significant research attention as phototheranostic agents. Herein, based on thieno[3,2-b]thienyl-DPP (TT-DPP), a near-infrared small molecule photosensitizer diethyl 3,3'-((((2,5-bis(2-decyltetradecyl)-3,6-dioxo-2,3,5,6-tetrahydropyrrolo[3,4-c]pyrrole-1,4-diyl)bis(thieno[3,2-b]thiophene-5,2-diyl))bis-(4,1-phenylene))bis(7-bromo-10H-phenothiazine-10,3-diyl))(2E,2'E)-diacrylate (PDBr), with a high singlet oxygen (¹O₂) quantum yield of 67%, was developed. After nano-precipitation, the hydrophilic PDBr NPs present an encouraging photothermal conversion efficiency of 35.7% and excellent fluorescence/infrared-thermal imaging performance. In vitro studies disclosed the high phototoxicity but low dark cytotoxicity of PDBr NPs to tumor cells. Furthermore, PDBr NPs can effectively impede the tumor growth without noticeable side effects in living mice through imaging-guided synergistic photothermal/photodynamic therapy. Therefore, PDBr NPs could be a promising nanotheranostic agent for imaging-guided synergistic photothermal and photodynamic therapy in the clinic.

Low Power Single Laser Activated Synergistic Cancer Phototherapy Using Photosensitizer Functionalized Dual Plasmonic Photothermal Nanoagents

Combination therapy, especially photodynamic/photothermal therapy (PDT/PTT), has shown promising applications in cancer therapy. However, sequential irradiation by two different laser sources and even the utilization of single high-power laser to induce either combined PDT/PTT or individual PTT will be subjected to prolonged treatment time, complicated treatment process, and potential skin burns. Thus, low power single laser activatable combined PDT/PTT is still a formidable challenge. Herein, we propose an effective strategy to achieve synergistic cancer phototherapy under low power single laser irradiation for short duration. By taking advantage of dual plasmonic PTT nanoagents (AuNRs/MoS₂), a significant increase in temperature up to 60 °C with an overall photothermal conversion efficiency (PCE) of 68.8% was achieved within 5 min under very low power (0.2 W/cm²) NIR laser irradiation. The enhanced PCE and PTT performance is attributed to the synergistic plasmonic PTT effect (PPTT) of dual plasmonic nanoagents, promoting simultaneous release (85%) of electrostatically bonded indocyanine green (ICG) to induce PDT effects, offering simultaneous PDT/synergistic PPTT. Both in vitro and in vivo investigations reveal complete cell/tumor eradication, implying that simultaneous PDT/synergistic PPTT effects induced by AuNRs/MoS₂-ICG are much superior over individual PDT or synergistic PPTT. Notably, synergistic PPTT induced by dual plasmonic nanoagents also demonstrates higher in vivo antitumor efficacy than either individual PDT or PTT agents. Taken together, under single laser activation with low power density, the proposed strategy of simultaneous PDT/synergistic PPTT effectively reduces the treatment time, achieves high therapeutic index, and offers safe treatment option, which may serve as a platform to develop safer and clinically translatable approaches for accelerating cancer therapeutics.

Confined growth of multiple gold nanorices in dual-mesoporous silica nanospheres for improved computed tomography imaging and photothermal therapy

INTRODUCTION

In this work, we have developed a novel "confined-growth" strategy to synthesize PEGylated multiple gold nanorices-encapsulated dual-mesoporous silica nanospheres (designated as PEGylated MGNRs@DMSSs) containing both small mesopores (2.5 nm) in the shell and large mesopores (21.7 nm) in the core based on a well-established, seed-mediated growth method. The photothermal effect and CT imaging ability were also studied.

METHODS

The nanoparticles were characterized by Fourier transform infrared (FT-IR) spectra, N2 absorption isotherms, Field-emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), Inductively coupled plasma atomic emission spectroscopy (ICP-AES) and Confocal microscopy.

RESULTS

The longitudinally-localized surface (LSPR) absorption properties of MGNRs@DMSSs can be easily tuned by altering the amount of HAuCl4 in the gold growth solution. Additionally, the resultant PEGylated MGNRs@DMSSs have monodispersed, spherical morphology and good colloidal stability in an aqueous solution. More importantly, when exposed to NIR irradiation, the PEGylated MGNRs@DMSSs exhibit both higher temperature increments and better photothermal effects than that of single PEGylated gold nanorods at nearly an equivalent LSPR absorption. In addition, as CT contrast agents, the PEGylated MGNRs@DMSSs display a better CT imaging performance, in comparison with single PEGylated gold nanorods at the same Au concentration.

CONCLUSION

Taken together, results indicate the potential for MGNRs@DMSSs used in CT imaging-guided photothermal therapy. Such a simple "confined-growth" strategy within a porous matrix offers a promising platform to design and prepare novel metal(s) oxide@silica nanocomposites for use in further cancer bio-imaging and therapy.

Ce6-Modified Carbon Dots for Multimodal-Imaging-Guided and Single-NIR-Laser-Triggered Photothermal/Photodynamic Synergistic Cancer Therapy by Reduced Irradiation Power

Photomediated cancer therapy, mainly including photothermal (PT) therapy (PTT) and photodynamic therapy (PDT), has attracted tremendous attention in recent years thanks to its noninvasive and stimuli-responsive features. The single mode of PTT or PDT, however, has obvious drawbacks, either requiring high-power laser irradiation to generate enough heat or only providing limited efficacy due to the hypoxia nature inside tumors. In addition, the reported synergistic PTT/PDT generally utilized two excitation sources to separately activate PTT and PDT, and the problem of high-power laser irradiation for PTT was still not well solved. Herein, a new concept, loading a small amount of photosensitizers onto a PTT agent (both of them can be triggered by a single-near-infrared (NIR) laser), was proposed to evade the shortcomings of PTT and PDT. To validate this idea, minute quantities of photosensitizer chlorin e6 (Ce6) (0.56% of mass) were anchored onto amino-rich red emissive carbon dots (RCDs) that possess superior photothermal (PT) character under 671 nm NIR laser (PT conversion efficiency to be 46%), and meanwhile the PDT of Ce6 can be activated by this laser irradiation as well. The findings demonstrate that Ce6-modified RCDs (named Ce6-RCDs) offer much higher cancer therapy efficacy under a reduced laser power density (i.e., 0.50 W cm^-2 at 671 nm) in vitro and in vivo than the equivalent RCDs or Ce6 under the same irradiation conditions. Besides, the Ce6-RCDs also exhibit multimodal imaging capabilities (i.e., fluorescence (FL), photoacoustic (PA), and PT), which can be employed for guidance of the phototherapy process. This study suggests not only a strategy to enhance cancer phototherapy efficacy but also a promising candidate (i.e., Ce6-RCDs) for multimodal FL/PA/PT imaging-guided and single-NIR-laser-triggered synergistic PTT/PDT for cancers by a reduced irradiation power.

Recent insights into near-infrared light-responsive carbon dots for bioimaging and cancer phototherapy

The current developments of NIR-responsive CDs and their applications in bioimaging and phototherapy are highlighted in this review.

Nanosonosensitizers for Highly Efficient Sonodynamic Cancer Theranostics

Background: Multifunctional nanoplatforms with diagnostic-imaging and targeted therapeutic functionality (theranostics) are of great interest in the field of precision nanomedicine. The emerging sonodynamic therapy (SDT) combined with sonosensitizers under the guidance of photoacoustic (PA) imaging is highly expected to accurately eliminate cancer cells/tissue. Methods: Unique core/shell-structured theranostic FA-HMME-MNPs-PLGA nanoparticles (FHMP NPs, FA: folate, HMME: hematoporphyrin monomethyl ether, MNPs: melanin nanoparticles, PLGA: poly (lactic-co-glycolic) acid) were constructed by the integration of MNPs (for PA imaging) in the core and HMME in the shell for enhanced PA imaging-guided SDT, which were further functionalized with a tumor-targeting ligand, FA. The PA imaging-guided SDT was systematically and successfully demonstrated both in vitro and in vivo. The high biosafety of FHMP NPs was also systematically evaluated. Results: The synthesized FHMP NPs with a broad optical absorption not only possess high PA-imaging contrast enhancement capability but also exhibit significant SDT efficiency. Importantly, such a PLGA based nanoplatform improved light stability of HMME, enhancing sonodynamic performance and facilitated delivery of MNPs to the tumor region. Meanwhile, a combined effect between HMME and MNPs was discovered and verified. Furthermore, a sonosensitizer assisted by ultrasound irradiation engenders reactive oxygen species (ROS)-mediated cytotoxicity toward tumor cells/tissue. Both in vitro cell-level and systematic in vivo xenograft evaluations on tumor-bearing mice demonstrated that the selective killing effect of ROS on tumor cells was assisted by FHMP NPs, which played an active role in the suppression of tumor growth with high biosafety. Conclusion: A theranostic nanoplatform was successfully constructed, achieving PA imaging-guided SDT against breast cancer cells/tissue. More importantly, MNPs and HMME in one platform with combined effect for enhancing PA imaging was demonstrated. This unique theranostic nanoplatform with multiple capabilities paves a new way toward personalized medicine by rational utilization.

Gold Rod-Polyethylene Glycol-Carbon Dot Nanohybrids as Phototheranostic Probes

Emphasis using phototheranostics has been placed on the construction of multifunctional nanoplatforms for simultaneous tumor diagnosis and therapy. Herein, we put forth a novel nanosized luminescent material using the incorporation of red emissive carbon dots on gold nanorods through polyethylene glycol as a covalent linkage for dual-modal imaging and photothermal therapy. The novel nanohybrids, not only retain the optical properties of the gold nanorod and carbon dots, but also possess superior imaging performance in both confocal laser scanning microscopy and fluorescence lifetime imaging microscopy. The nanohybrids also exhibit excellent photothermal performance as phototheranostic nanohybrid probes for in vitro assays. This study promises a new multifunctional nanoplatform for cancer diagnostics and therapeutics.

Multifunctional Carbon-Based Nanomaterials: Applications in Biomolecular Imaging and Therapy

Molecular imaging has been widely used not only as an important detection technology in the field of medical imaging for cancer diagnosis but also as a theranostic approach for cancer in recent years. Multifunctional carbon-based nanomaterials (MCBNs), characterized by unparalleled optical, electronic, and thermal properties, have attracted increasing interest and demonstrably hold the greatest promise in biomolecular imaging and therapy. As such, it should come as no surprise that MCBNs have already revealed a great deal of potential applications in biomedical areas, such as bioimaging, drug delivery, and tumor therapy. Carbon nanomaterials can be categorized as graphene, single-walled carbon nanotubes, mesoporous carbon, nanodiamonds, fullerenes, or carbon dots on the basis of their morphologies. In this article, reports of the use of MCBNs in various chemical conjugation/functionalization strategies, focusing on their applications in cancer molecular imaging and imaging-guided therapy, will be comprehensively summarized. MCBNs show the possibility to serve as optimal candidates for precise cancer biotheranostics.

Organic Dye Based Nanoparticles for Cancer Phototheranostics

Phototheranostics, which simultaneously combines photodynamic and/or photothermal therapy with deep-tissue diagnostic imaging, is a promising strategy for the diagnosis and treatment of cancers. Organic dyes with the merits of strong near-infrared absorbance, high photo-to-radical and/or photothermal conversion efficiency, great biocompatibility, ready chemical structure fine-tuning capability, and easy metabolism, have been demonstrated as attractive candidates for clinical phototheranostics. These organic dyes can be further designed and fabricated into nanoparticles (NPs) using various strategies. Compared to free molecules, these NPs can be equipped with multiple synergistic functions and show longer lifetime in blood circulation and passive tumor-targeting property via the enhanced permeability and retention effect. In this article, the recent progress of organic dye-based NPs for cancer phototheranostic applications is summarized, which extends the anticancer arsenal and holds promise for clinical uses in the near future.

Loading of Indocyanine Green within Polydopamine-Coated Laponite Nanodisks for Targeted Cancer Photothermal and Photodynamic Therapy

The combination of photothermal therapy (PTT) and photodynamic therapy (PDT) in cancer treatment has attracted much attention in recent years. However, developing highly efficient and targeted therapeutic nanoagents for amplifying PTT and PDT treatments remains challenging. In this work, we developed a novel photothermal and photodynamic therapeutic nanoplatform for treatment of cancer cells overexpressing integrin αvβ₃ through the coating of polydopamine (PDA) on indocyanine green (ICG)-loaded laponite (LAP) and then further conjugating polyethylene glycol-arginine-glycine-aspartic acid (PEG-RGD) as targeted agents on the surface. The ICG/LAP⁻PDA⁻PEG⁻RGD (ILPR) nanoparticles (NPs) formed could load ICG with a high encapsulation efficiency of 94.1%, improve the photostability of loaded ICG dramatically via the protection of PDA and LAP, and display excellent colloidal stability and biocompatibility due to the PEGylation. Under near-infrared (NIR) laser irradiation, the ILPR NPs could exert enhanced photothermal conversion reproducibly and generate reactive oxygen species (ROS) efficiently. More importantly, in vitro experiments proved that ILPR NPs could specifically target cancer cells overexpressing integrin αvβ₃, enhance cellular uptake due to RGD-mediated targeting, and exert improved photothermal and photodynamic killing efficiency against targeted cells under NIR laser irradiation. Therefore, ILPR may be used as effective therapeutic nanoagents with enhanced photothermal conversion performance and ROS generating ability for targeted PTT and PDT treatment of cancer cells with integrin αvβ₃ overexpressed.

Synthesis of carbon dots from Hypocrella bambusae for bimodel fluorescence/photoacoustic imaging-guided synergistic photodynamic/photothermal therapy of cancer

As phototheranostic agents, carbon dots (CDs), have recently drawn considerable attention due to their excellent physicochemical properties. However, the complex synthetic route and high-cost of CDs greatly limit their practical application. To address this issue, given their nearly infinite supply from nature, Hypocrella bambusae is used as the precursor for the preparation of CDs in this study. The obtained Hypocrella bambusae CDs (HBCDs) possess good water solubility, broad absorption (350-800 nm), red-light emission (maximum peak at 610 nm), and low biotoxicity. Moreover, HBCDs can highly generate ¹O₂ (0.38) and heat (27.6%) under 635 nm laser irradiation. These excellent properties of HBCDs capacitate them to be utilized for bimodal fluorescence/photoacoustic imaging-guided synergistic photodynamic therapy (PDT)/photothermal therapy (PTT). This work provides a new candidate for tumor treatment with the combination of PDT and PTT, and explores a novel approach for the preparation of CD-based phototheranostic agents with natural biomass as raw carbon sources.

A Magnetofluorescent Carbon Dot Assembly as an Acidic H2 O2 -Driven Oxygenerator to Regulate Tumor Hypoxia for Simultaneous Bimodal Imaging and Enhanced Photodynamic Therapy

Recent studies indicate that carbon dots (CDs) can efficiently generate singlet oxygen (¹ O₂ ) for photodynamic therapy (PDT) of cancer. However, the hypoxic tumor microenvironment and rapid consumption of oxygen in the PDT process will severely limit therapeutic effects of CDs due to the oxygen-dependent PDT. Thus, it is becoming particularly important to develop a novel CD as an in situ tumor oxygenerator for overcoming hypoxia and substantially enhancing the PDT efficacy. Herein, for the first time, magnetofluorescent Mn-CDs are successfully prepared using manganese(II) phthalocyanine as a precursor. After cooperative self-assembly with DSPE-PEG, the obtained Mn-CD assembly can be applied as a smart contrast agent for both near-infrared fluorescence (FL) (maximum peak at 745 nm) and T₁ -weighted magnetic resonance (MR) (relaxivity value of 6.97 mM^-1 s^-1 ) imaging. More interestingly, the Mn-CD assembly can not only effectively produce ¹ O₂ (quantum yield of 0.40) but also highly catalyze H₂ O₂ to generate oxygen. These collective properties of the Mn-CD assembly enable it to be utilized as an acidic H₂ O₂ -driven oxygenerator to increase the oxygen concentration in hypoxic solid tumors for simultaneous bimodal FL/MR imaging and enhanced PDT. This work explores a new biomedical use of CDs and provides a versatile carbon nanomaterial candidate for multifunctional nanotheranostic applications.

Facile preparation of carbon-dot-supported nanoflowers for efficient photothermal therapy of cancer cells

Novel C-dots@Au composites have been developed by one-step preparation for efficient photothermal therapy of cancer cells.

The synthesis of LA-Fe3O4@PDA-PEG-DOX for photothermal therapy–chemotherapy

The improved cell uptake and the synergistic effect of chemo-/photothermal therapy ensure the enhanced specific cytotoxicity toward HepG2 cells.

Engineered fluorescent carbon dots as promising immune adjuvants to efficiently enhance cancer immunotherapy

Carbon dots, as vaccine adjuvants, have been firstly engineered for cancer immunotherapy, providing many possibilities for biomedical applications.

A cellular/intranuclear dual-targeting nanoplatform based on gold nanostar for accurate tumor photothermal therapy

A versatile GNS-NLS@HA nanoplatform was constructed for tumor cellular/intranuclear dual-targeting photothermal therapy. It displayed excellent tumor inhibition efficiency as well as anti-metastasis ability in vivo.

A perylene diimide zwitterionic polymer for photoacoustic imaging guided photothermal/photodynamic synergistic therapy with single near-infrared irradiation

A biocompatible zwitterionic polymer (PDS-PDI) was designed for PAI guided synergistic PDT and PTT with single NIR light irradiation.

Cap-free dual stimuli-responsive biodegradable nanocarrier for controlled drug release and chemo-photothermal therapy

The cap-free nanocarrier with fast biodegradability achieved controlled release and chemo-photothermal therapy in vitro.

Tumor-targeted nanoprobes for enhanced multimodal imaging and synergistic photothermal therapy: core-shell and dumbbell Gd-tailored gold nanorods

Multifunctional nanoprobes, due to their unique nanocomposite structures, have prominent advantages that combine multimodal imaging of a tumor with photothermal therapy. However, they remain a challenge for constructing nanostructures via conventional approaches due to the peculiar environmental sensitivity of each component. Here, we report the design and synthesis of Gd-based nanoparticle-tailored gold nanorods with distinctive core-shell and dumbbell nanoarchitectures (NAs) by a specific synthesis technology. The prepared NAs possess a tunable particle size of 80-120 nm in length and 50-90 nm in diameter, which are suitable for cellular uptake and passive targeting of a tumor. The formation of two distinct heterostructures and their underlying mechanism were studied through systematic investigations on the controllable synthesis process. The as-prepared nanoprobes possess an ultrahigh longitudinal relaxivity (r₁) of 22.69 s^-1 mM^-1 and thus a significant magnetic resonance imaging signal enhancement has been observed in mice tumors. The NAs, especially the dumbbell type, show a vivid two-photon cell imaging and a remarkable photothermal conversion efficiency owing to their superior longitudinal surface plasmon resonance. Both in vitro cytotoxicity and in vivo immunotoxicity assays give substantial evidence of excellent biocompatibility attained in the NAs. The development of multifunctional targeting nanoprobes in this study could provide guidance for tailored design and controllable synthesis of heterostructured nanocomposites utilized for multimodal imaging and photothermal therapy of cancer.

Plasmonic enhancement of cyanine dyes for near-infrared light-triggered photodynamic/photothermal therapy and fluorescent imaging

Near-infrared (NIR) triggered cyanine dyes have attracted considerable attention in multimodal tumor theranostics. However, NIR cyanine dyes used in tumor treatment often suffer from low fluorescence intensity and weak singlet oxygen generation efficiency, resulting in inadequate diagnostic and therapy efficacy for tumors. It is still a great challenge to improve both the photodynamic therapy (PDT) and fluorescent imaging (FLI) efficacy of cyanine dyes in tumor applications. Herein, a novel multifunctional nanoagent AuNRs@SiO₂-IR795 was developed to realize the integrated photothermal/photodynamic therapy (PTT/PDT) and FLI at a very low dosage of IR795 (0.4 μM) based on metal-enhanced fluorescence (MEF) effects. In our design, both the fluorescence intensity and reactive oxygen species of AuNRs@SiO₂-IR795 nanocomposites were significantly enhanced up to 51.7 and 6.3 folds compared with free IR795, owing to the localized surface plasmon resonance band of AuNRs overlapping with the absorption or fluorescence emission band of the IR795 dye. Under NIR laser irradiation, the cancer cell inhibition efficiency in vitro with synergetic PDT/PTT was up to 82.3%, compared with 10.3% for free IR795. Moreover, the enhanced fluorescence intensity of our designed nanocomposites was helpful to track their behavior in tumor cells. Therefore, our designed nanoagents highlight the applications of multimodal diagnostics and therapy in tumors based on MEF.

Single Near-Infrared Emissive Polymer Nanoparticles as Versatile Phototheranostics

Attaining consistently high performance of diagnostic and therapeutic functions in one single nanoplatform is of great significance for nanomedicine. This study demonstrates the use of donor-acceptor (D-A) structured polymer (TBT) to develop a smart "all-five-in-one" theranostic that conveniently integrates fluorescence/photoacoustic/thermal imaging and photodynamic/photothermal therapy into single nanoparticle. The prepared nanoparticles (TBTPNPs) exhibit near-infrared emission, high water solubility, excellent light resistance, good pH stability, and negligible toxicity. Additionally, the TBTPNPs exhibit an excellent singlet oxygen (1O2) quantum yield (40%) and high photothermal conversion efficiency (37.1%) under single-laser irradiation (635 nm). Apart from their two phototherapeutic modalities, fluorescence, photoacoustic signals, and thermal imaging in vivo can be simultaneously achieved because of their enhanced permeability and retention effects. This work demonstrates that the prepared TBTPNPs are "all-five-in-one" phototheranostic agents that can exhibit properties to satisfy the "one-fits-all" requirement for future phototheranostic applications. Thus, the prepared TBTPNPs can provide fundamental insights into the development of PNP-based nanoagents for cancer therapy.

Polyaniline-loaded γ-polyglutamic acid nanogels as a platform for photoacoustic imaging-guided tumor photothermal therapy

We report the facile synthesis of polyaniline (PANI)-loaded γ-polyglutamic acid (γ-PGA) nanogels (NGs) for photoacoustic (PA) imaging-guided photothermal therapy (PTT) of tumors. In this work, γ-PGA NGs were first formed via a double emulsion approach, followed by crosslinking with cystamine dihydrochloride (Cys) via 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride coupling chemistry. The formed γ-PGA/Cys NGs were employed as a nanoreactor to load aniline monomers via an electrostatic interaction for subsequent in situ polymerization in the presence of ammonium persulfate. The resulting γ-PGA/Cys@PANI NGs were thoroughly characterized. It is shown that the γ-PGA/Cys@PANI NGs with an average size of 71.9 nm are dispersible in water, colloidally stable, and cytocompatible and hemocompatible in the concentration range studied. The strong near-infrared (NIR) absorbance renders the NGs with good PA imaging contrast enhancement and photothermal conversion properties. With these excellent properties and biocompatibility, the developed γ-PGA/Cys@PANI NGs are able to be used for PA imaging-guided PTT of cancer cells in vitro and a xenografted tumor model in vivo. This unique theranostic nanoplatform may be further loaded with other imaging or therapeutic elements, or modified with targeting ligands, thereby providing a ubiquitous platform for multimode imaging and combinational therapy of different biosystems.

Biocompatible Iron Phthalocyanine-Albumin Assemblies as Photoacoustic and Thermal Theranostics in Living Mice

Exploring novel and versatile nanomaterials for the construction of personalized multifunctional phototheranostics with significant potentials in bioimaging-guided tumor phototherapies has attracted considerable attention. Herein, the phototheranostic agent human serum albumin-iron (II) phthalocyanine FePc nanoparticles (HSA-FePc NPs) were fabricated for photoacoustic (PA) imaging-guided photothermal therapy (PTT) of cancer in vivo. The prepared HSA-FePc NPs exhibited high stability, efficient NIR absorption, good capability and stability of photothermal behavior with a high photothermal conversion efficiency of ∼44.4%, high contrast and spatial resolution of PA imaging, efficient cancer therapy, and low long-term toxicity. This potent multifunctional phototheranostic is, therefore, very promising and favorable for effective, precise, and safe antitumor treatment in clinical application.

Systematic study of interdependent relationship on gold nanorod synthesis assisted by electron microscopy image analysis

Here, we systematically investigated the independent, multiple, and synergic effects of three major components, namely, ascorbic acid (AA), seed, and silver ions (Ag⁺), on the characteristics of gold nanorods (GNRs), i.e., longitudinal localized surface plasmon resonance (LSPR) peak position, shape, size, and monodispersity. To quantitatively assess the shape and dimensions of GNRs, we used an automated transmission electron microscopy image analysis method using a MATLAB-based code developed in-house and the concept of solidity, which is the ratio between the area of a GNR and the area of its convex hull. The solidity of a straight GNR is close to 1, while it decreases for both dumbbell- and dogbone-shaped GNRs. We found that the LSPR peak position, shape, and monodispersity of the GNRs all altered simultaneously with changes in the amounts of individual components. For example, as the amount of AA increased, both the LSPR peak and solidity decreased, while the polydispersity increased. In contrast, as the amount of seeds increased, both the LSPR and solidity increased, while the monodispersity improved. More importantly, we found that the influence of each component can actually change depending on the composition of the GNR growth solution. For instance, the LSPR peak position red-shifted as the amount of AA increased when the seed content was low, whereas it blue-shifted when the seed content was high.

Self-Assembled Carbon Dot Nanosphere: A Robust, Near-Infrared Light-Responsive, and Vein Injectable Photosensitizer

Self-assembly "activated" carbon dot photosensitizer: a robust, NIR-light responsive, and vein injectable carbon dot nanosphere (CDNS) photosensitizer with ¹ O₂ quantum yield of 0.45 under 671 nm laser irradiation has been developed through self-assembly using individual CD as building units. This study develops the biomedical applications of CD, highlights the self-assembly for designing well-defined CD-based photosensitizers, and promotes future explorations of this CDNS photosensitizer in nanomedical and clinical applications.

Versatile Polymer Nanoparticles as Two-Photon-Triggered Photosensitizers for Simultaneous Cellular, Deep-Tissue Imaging, and Photodynamic Therapy

Clinical applications of current photodynamic therapy (PDT) photosensitizers (PSs) are often limited by their absorption in the UV-vis range that possesses limited tissue penetration ability, leading to ineffective therapeutic response for deep-seated tumors. Alternatively, two-photon excited PS (TPE-PS) using NIR light triggered is one the most promising candidates for PDT improvement. Herein, multimodal polymer nanoparticles (PNPs) from polythiophene derivative as two-photon fluorescence imaging as well as two-photon-excited PDT agent are developed. The prepared PNPs exhibit excellent water dispersibility, high photostability and pH stability, strong fluorescence brightness, and low dark toxicity. More importantly, the PNPs also possess other outstanding features including: (1) the high ¹ O₂ quantum yield; (2) the strong two-photon-induced fluorescence and efficient ¹ O₂ generation; (3) the specific accumulation in lysosomes of HeLa cells; and (4) the imaging detection depth up to 2100 µm in the mock tissue under two-photon. The multifunctional PNPs are promising candidates as TPE-PDT agent for simultaneous cellular, deep-tissue imaging, and highly efficient in vivo PDT of cancer.

Polymer nanoparticles with high photothermal conversion efficiency as robust photoacoustic and thermal theranostics

Synthesis of photothermal agents with absorption in the near-infrared (NIR) region and featuring excellent photostability, high photothermal conversion efficiency, and good biocompatibility is necessary for the application of photothermal therapy (PTT). In this work, a low band gap thiophene-benzene-diketopyrrolopyrrole (TBD)-based polymer was synthesized and used to fabricate TBD polymer nanoparticles (TBDPNPs) through a one-step nanoprecipitation method. The obtained near-infrared-absorbing TBDPNPs presented good water dispersibility, high photothermal stability, and low toxicity. Significantly, the TBDPNPs exhibited an ultrahigh photothermal conversion efficiency of approximately 68.1% under 671 nm laser irradiation. In addition, photoacoustic (PA) imaging, with high spatial resolution and deep tissue penetration, showed that the TBDPNPs targeted tumor sites through the enhanced permeability and retention effect. Therefore, the robust TBDPNPs with a photothermal conversion efficiency of 68.1% can serve as an excellent therapeutic agent for PA-imaging-guided PTT.

Diketopyrrolopyrrole-Triphenylamine Organic Nanoparticles as Multifunctional Reagents for Photoacoustic Imaging-Guided Photodynamic/Photothermal Synergistic Tumor Therapy

Herein, a donor-acceptor-donor (D-A-D) structured small molecule (DPP-TPA) is designed and synthesized for photoacoustic imaging (PAI) guided photodynamic/photothermal synergistic therapy. In the diketopyrrolopyrrole (DPP) molecule, a thiophene group is contained to increase the intersystem crossing (ISC) ability through the heavy atom effect. Simultaneously, triphenylamine (TPA) is introduced for bathochromic shift absorption as well as charge transport capacity enhancement. After formation of nanoparticles (NPs, ∼76 nm) by reprecipitation, the absorption of DPP-TPA NPs further displays obvious bathochromic-shift with the maximum absorption peak at 660 nm. What's more, the NPs architecture enhances the D-A-D structure, which greatly increases the charge transport capacity and impels the charge to generate heat by light. DPP-TPA NPs present high photothermal conversion efficiency (η = 34.5%) and excellent singlet oxygen (¹O₂) generation (Φ_Δ = 33.6%) under 660 nm laser irradiation. PAI, with high spatial resolution and deep biotissue penetration, indicates DPP-TPA NPs can rapidly target the tumor sites within 2 h by the enhanced permeability and retention (EPR) effect. Importantly, DPP-TPA NPs could effectively hinder the tumor growth by photodynamic/photothermal synergistic therapy in vivo even at a low dosage (0.2 mg/kg) upon laser irradiation (660 nm 1.0 W/cm²). This study illuminates the photothermal conversion mechanism of small organic NPs and demonstrates the promising application of DPP-TPA NPs in PAI guided phototherapy.

Janus nanostructures formed by mesoporous silica coating Au nanorods for near-infrared chemo–photothermal therapy

Mesoporous silica was partly coated on AuNRs (Janus AuNRs@mSiO₂) as a hyperthermia and drug delivery platform for chemo–photothermal therapy.

Near-infrared light-mediated LA-UCNPs@SiO2-C/HA@mSiO2-DOX@NB nanocomposite for chemotherapy/PDT/PTT and imaging

Upon 980 nm light irradiation, multiple-emission can not only induce chemotherapy/PDT/PTT but also imaging.

Luminescent CaTiO3:Yb,Er nanofibers co-conjugated with Rose Bengal and gold nanorods for potential synergistic photodynamic/photothermal therapy

CaTiO₃:Yb,Er nanofibers, co-conjugated with Rose Bengal and gold nanorods, enable a synergistic photodynamic/photothermal phenomenon for superior cancer cell killing effect.

Firmly anchored photosensitizer Chlorin e6 to layered double hydroxide nanoflakes for highly efficient photodynamic therapy in vivo

We covalently conjugate photosensitizer Chlorin e6 (Ce6) to polyethylene glycol modified layered double hydroxides and produce hybrid nanoflakes with excellentin vivophotodynamic therapeutic efficiency and safety profiles.

Carbon-Based Materials for Photo-Triggered Theranostic Applications

Carbon-based nanomaterials serve as a type of smart material for photo-triggered disease theranostics. The inherent physicochemical properties of these nanomaterials facilitate their use for less invasive treatments. This review summarizes the properties and applications of materials including fullerene, nanotubes, nanohorns, nanodots and nanographenes for photodynamic nanomedicine in cancer and antimicrobial therapies. Carbon nanomaterials themselves do not usually act as photodynamic therapy (PDT) agents owing to the high hydrophobicity, however, when the surface is passivated or functionalized, these materials become great vehicles for PDT. Moreover, conjugation of carbonaceous nanomaterials with the photosensitizer (PS) and relevant targeting ligands enhances properties such as selectivity, stability, and high quantum yield, making them readily available for versatile biomedical applications.

Gd-Hybridized Plasmonic Au-Nanocomposites Enhanced Tumor-Interior Drug Permeability in Multimodal Imaging-Guided Therapy

An original gadolinium-hybridized plasmonic gold nanocomposite is fabricated to provide an insightful and attractive strategy to overcome both the physiological and pathological barriers of tumor, and increase the transportation and permeability of imaging agents and drugs in tumor interior for achieving high-sensitive multimodal imaging and simultaneously improving the therapeutic efficacy of cancer.