Highly absorbing multispectral near-infrared polymer nanoparticles from one conjugated backbone for photoacoustic imaging and photothermal therapy

Synthesis on NIR-II Multifunctional Imaging and Photothermal Therapy of a Novel Water-Soluble Molecule

The synthesis of water-soluble symmetric molecules with donor-acceptor-donor (D-A-D) structure is reported. The compound is connected by π bridge with 2-bromofluorene external polyethylene glycol 2000 as the shielding unit, and donor component and pyrrolopyrrole (DPP) as the acceptor unit. The D-A-D double donor fluorescent molecule P2-DPP is obtained by coupling reaction. The absorption peak and emission peak of the fluorescent molecule P2-DPP are 600 and 1020 nm, respectively. It has potential excellent imaging characteristics. It does not need to use nanoparticles formed by the DSPE-MPEG amphiphilic block to form micelles. The quantum yield reaches 0.6% and the penetration depth can reach 10 mm. The chemical is capable of achieving liver and renal metabolism. It has a good application prospect in the photothermal therapy of mouse tumors and realizes the integration of biological diagnosis and treatment.

Semiconducting polymer dots for multifunctional integrated nanomedicine carriers

The expansion applications of semiconducting polymer dots (Pdots) among optical nanomaterial field have long posed a challenge for researchers, promoting their intelligent application in multifunctional nano-imaging systems and integrated nanomedicine carriers for diagnosis and treatment. Despite notable progress, several inadequacies still persist in the field of Pdots, including the development of simplified near-infrared (NIR) optical nanoprobes, elucidation of their inherent biological behavior, and integration of information processing and nanotechnology into biomedical applications. This review aims to comprehensively elucidate the current status of Pdots as a classical nanophotonic material by discussing its advantages and limitations in terms of biocompatibility, adaptability to microenvironments in vivo, etc. Multifunctional integration and surface chemistry play crucial roles in realizing the intelligent application of Pdots. Information visualization based on their optical and physicochemical properties is pivotal for achieving detection, sensing, and labeling probes. Therefore, we have refined the underlying mechanisms and constructed multiple comprehensive original mechanism summaries to establish a benchmark. Additionally, we have explored the cross-linking interactions between Pdots and nanomedicine, potential yet complete biological metabolic pathways, future research directions, and innovative solutions for integrating diagnosis and treatment strategies. This review presents the possible expectations and valuable insights for advancing Pdots, specifically from chemical, medical, and photophysical practitioners' standpoints.

Rational Design of NIR-II Emitting Conjugated Polymer Derived Nanoparticles for Image-Guided Cancer Interventions

Due to the reduced absorption, light scattering, and tissue autofluorescence in the NIR-II (1000-1700 nm) region, significant efforts are underway to explore diverse material platforms for in vivo fluorescence imaging, particularly for cancer diagnostics and image-guided interventions. Of the reported imaging agents, nanoparticles derived from conjugated polymers (CPNs) offer unique advantages to alternative materials including biocompatibility, remarkable absorption cross-sections, exceptional photostability, and tunable emission behavior independent of cell labeling functionalities. Herein, the current state of NIR-II emitting CPNs are summarized and structure-function-property relationships are highlighted that can be used to elevate the performance of next-generation CPNs. Methods for particle processing and incorporating cancer targeting modalities are discussed, as well as detailed characterization methods to improve interlaboratory comparisons of novel materials. Contemporary methods to specifically apply CPNs for cancer diagnostics and therapies are then highlighted. This review not only summarizes the current state of the field, but offers future directions and provides clarity to the advantages of CPNs over other classes of imaging agents.

H2O2-triggered controllable carbon monoxide delivery for photothermally augmented gas therapy

Carbon monoxide (CO) gas therapy has shown great potential as a very promising approach in the ongoing fight against tumors. However, delivering unstable CO to the tumor site and safely releasing it for maximum efficacy still have unsatisfactory outcomes. In this study, we've developed nanotheranostics (IN-DPPCO NPs) based on conjugated polymer IN-DPP and carbon monoxide (CO) carrier polymer mPEG(CO) for photothermal augmented gas therapy. The IN-DPPCO NPs can release CO with the hydrogen peroxide (H2O2) overexpressed in the tumor microenvironment. Meanwhile, IN-DPPCO NPs exhibit strong absorption in the near-infrared window, showing a high photothermal conversion efficiency of up to 41.5% under 808 nm laser irradiation. In vitro and in vivo experiments demonstrate that these nanotheranostics exhibit good biocompatibility. Furthermore, the synergistic CO/photothermal therapy shows enhanced therapeutic efficacy compared to gas therapy alone. This work highlights the great promise of conjugated polymer nanoparticles as versatile nanocarriers for spatiotemporally controlled and on-demand delivery of gaseous messengers to achieve precision cancer theranostics.

Stimuli-Responsive Polymer-Based Nanosystems for Cancer Theranostics

Stimuli-responsive polymers can respond to internal stimuli, such as reactive oxygen species (ROS), glutathione (GSH), and pH, biological stimuli, such as enzymes, and external stimuli, such as lasers and ultrasound, etc., by changing their hydrophobicity/hydrophilicity, degradability, ionizability, etc., and thus have been widely used in biomedical applications. Due to the characteristics of the tumor microenvironment (TME), stimuli-responsive polymers that cater specifically to the TME have been extensively used to prepare smart nanovehicles for the targeted delivery of therapeutic and diagnostic agents to tumor tissues. Compared to conventional drug delivery nanosystems, TME-responsive nanosystems have many advantages, such as high sensitivity, broad applicability among different tumors, functional versatility, and improved biosafety. In recent years, a great deal of research has been devoted to engineering efficient stimuli-responsive polymeric nanosystems, and significant improvement has been made to both cancer diagnosis and therapy. In this review, we summarize some recent research advances involving the use of stimuli-responsive polymer nanocarriers in drug delivery, tumor imaging, therapy, and theranostics. Various chemical stimuli will be described in the context of stimuli-responsive nanosystems. Accordingly, the functional chemical groups responsible for the responsiveness and the strategies to incorporate these groups into the polymer will be discussed in detail. With the research on this topic expending at a fast pace, some innovative concepts, such as sequential and cascade drug release, NIR-II imaging, and multifunctional formulations, have emerged as popular strategies for enhanced performance, which will also be included here with up-to-date illustrations. We hope that this review will offer valuable insights for the selection and optimization of stimuli-responsive polymers to help accelerate their future applications in cancer diagnosis and treatment.

Thermo-Responsive Hydrogels Coupled with Photothermal Agents for Biomedical Applications

Intelligent hydrogels are materials with abilities to change their chemical nature or physical structure in response to external stimuli showing promising potential in multitudinous applications. Especially, photo-thermo coupled responsive hydrogels that are prepared by encapsulating photothermal agents into thermo-responsive hydrogel matrix exhibit more attractive advantages in biomedical applications owing to their spatiotemporal control and precise therapy. This work summarizes the latest progress of the photo-thermo coupled responsive hydrogel in biomedical applications. Three major elements of the photo-thermo coupled responsive hydrogel, i.e., thermo-responsive hydrogel matrix, photothermal agents, and construction methods are introduced. Furthermore, the recent developments of these hydrogels for biomedical applications are described with some selected examples. Finally, the challenges and future perspectives for photo-thermo coupled responsive hydrogels are outlined.

Silica-Based Platform Decorated with Conjugated Polymer Dots and Prussian Blue for Improved Photodynamic Cancer Therapy

To advance cancer treatment, we have developed a novel composite material consisting of conjugated polymer dots (CPDs) and Prussian blue (PB) particles, which were immobilized on, and encapsulated within, silica particles, respectively. The CPDs functioned as both a photosensitizer and a photodynamic agent, and the PB acted as a photothermal agent. The silica platform provided a biocompatible matrix that brought the two components into close proximity. Under laser irradiation, the fluorescence from the CPDs in the composite material enabled cell imaging and was subsequently converted to thermal energy by PB. This efficient energy transfer was accomplished because of the spectral overlap between the emission of donor CPDs and the absorbance of acceptor PB. The increase in local temperature in the cells resulted in a significant increase in the amount of reactive oxygen species (ROS) generated by CPDs, in which their independent use did not produce sufficient ROS for cancer cell treatment. To assess the impact of the enhanced ROS generation by the composite material, we conducted experiments using cancer cells under 532 nm laser irradiation. The results showed that with the increase in local temperature, the generated ROS increased by 30% compared with the control, which did not contain PB. When the silica-based composite material was positioned at the periphery of the tumor for 120 h, it led to a much slower tumor growth than other materials tested. By using a CPD-based photodynamic therapy platform, a new simplified approach to designing and preparing cancer treatments could be achieved, which included photothermal PB-assisted enhanced ROS generation using a single laser. This advancement opens up an exciting new opportunity for effective cancer treatment.

NIR-II Absorbing Conjugated Polymer Nanotheranostics for Thermal Initiated NO Enhanced Photothermal Therapy

Photothermal therapy (PTT) has received constant attention as a promising cancer treatment. However, PTT-induced inflammation can limit its effectiveness. To address this shortcoming, we developed second near-infrared (NIR-II) light-activated nanotheranostics (CPNPBs), which include a thermosensitive nitric oxide (NO) donor (BNN6) to enhance PTT. Under a 1064 nm laser irradiation, the conjugated polymer in CPNPBs serves as a photothermal agent for photothermal conversion, and the generated heat triggers the decomposition of BNN6 to release NO. The combination of hyperthermia and NO generation under single NIR-II laser irradiation allows enhanced thermal ablation of tumors. Consequently, CPNPBs can be exploited as potential candidates for NO-enhanced PTT, holding great promise for their clinical translational development.

Near Infrared-Absorbing Nanoparticle-Mediated Endovascular Photothermal Precision Embolization of Tumor Feeding Vessels for Starvation Treatment

Photothermal therapy has attracted enormous attention as an efficient treatment modality in cancer ablation but still encounters a major bottleneck due to the limited penetration depth of light inside tissues. To overcome the challenge of deep tissue penetration, we present a strategy of endovascular photothermal precision embolization (EPPE), which employs an endovascular optical fiber to induce local embolization only in the entrance of feeding vessels through photothermal heating for the purpose of fully blocking the blood supply of the whole tumor. In EPPE, we apply a highly efficient and biocompatible photothermal agent, i.e., near-infrared (NIR)-light-absorbing diketopyrrolopyrrole-dithiophene-based nanoparticle, which exhibits a high cell-killing efficacy at a concentration of 200 μg/mL using 808 nm laser irradiation of 0.5 W/cm² within 5 min in both 2D cell culture and a 3D tumor spheroid model. We verify the feasibility of EPPE in an ex vivo organ-structured recellularized liver model and further confirm the in vivo efficacy of the photothermal treatment in a rat liver model. The photothermal treatment combined with the embolization effect holds promise to serve as an effective starvation therapy to treat tumors of varying sizes and locations.

Recent Advances in Photoacoustic Agents for Theranostic Applications

Photoacoustic agents are widely used in various theranostic applications. By evaluating the biodistribution obtained from photoacoustic images, the effectiveness of theranostic agents in terms of their delivery efficiency and treatment responses can be analyzed. Through this study, we evaluate and summarize the recent advances in photoacoustic-guided phototherapy, particularly in photothermal and photodynamic therapy. This overview can guide the future directions for theranostic development. Because of the recent applications of photoacoustic imaging in clinical trials, theranostic agents with photoacoustic monitoring have the potential to be translated into the clinical world.

Semiconducting Polymer Dots for Point-of-Care Biosensing and In Vivo Bioimaging: A Concise Review

In recent years, semiconducting polymer dots (Pdots) have attracted much attention due to their excellent photophysical properties and applicability, such as large absorption cross section, high brightness, tunable fluorescence emission, excellent photostability, good biocompatibility, facile modification and regulation. Therefore, Pdots have been widely used in various types of sensing and imaging in biological medicine. More importantly, the recent development of Pdots for point-of-care biosensing and in vivo imaging has emerged as a promising class of optical diagnostic technologies for clinical applications. In this review, we briefly outline strategies for the preparation and modification of Pdots and summarize the recent progress in the development of Pdots-based optical probes for analytical detection and biomedical imaging. Finally, challenges and future developments of Pdots for biomedical applications are given.

Nanoparticles for super-resolution microscopy: intracellular delivery and molecular targeting

Following an overview of the approaches and techniques used to acheive super-resolution microscopy, this review presents the advantages supplied by nanoparticle based probes for these applications. The various clases of nanoparticles that have been developed toward these goals are then critically described and these discussions are illustrated with a variety of examples from the recent literature.

Biomedical Photoacoustic Imaging for Molecular Detection and Disease Diagnosis: "Always-On" and "Turn-On" Probes

Photoacoustic (PA) imaging is a nonionizing, noninvasive imaging technique that combines optical and ultrasonic imaging modalities to provide images with excellent contrast, spatial resolution, and penetration depth. Exogenous PA contrast agents are created to increase the sensitivity and specificity of PA imaging and to offer diagnostic information for illnesses. The existing PA contrast agents are categorized into two groups in this review: "always-on" and "turn-on," based on their ability to be triggered by target molecules. The present state of these probes, their merits and limitations, and their future development, is explored.

Biomimetic semiconducting polymer dots for highly specific NIR-II fluorescence imaging of glioma

Glioma with very short medium survival time consists of 80% of primary malignant types of brain tumors. The unique microenvironment such as the existence of the blood-brain barrier (BBB) makes the glioma theranostics exhibit low sensitivity in diagnosis, a poor prognosis and low treatment efficacy. Therefore, the development of multifunctional nanoplatform that can cross BBB and target the glioma is essential for the high-sensitivity detection and ablation of cancer cells. In this study, C6 cell membrane-coated conjugated polymer dots (Pdots-C6) were constructed for targeted glioma tumor detection. As a new kind of biomimetic and biocompatible nanoprobes, Pdots-C6 preserve the complex biological functions of natural cell membranes while possessing physicochemical properties for NIR-II fluorescence imaging of glioma. After encapsulating C6 cell membrane on the surface of conjugated Pdots, Pdots-C6 exhibited the most favorable specific targeting capabilities in vitro and in vivo. In particular, this pilot study demonstrates that biomimetic nanoparticles offer a potential tool to enhance specific targeting to the brain, hence improving glioma tumor detection accuracy.

A rapid-triggered approach towards antibacterial hydrogel wound dressing with synergic photothermal and sterilization profiles

Developing non-antibiotic-dependent antibacterial hydrogels for repairing infected skin defect remains largely unexplored. Herein, a synergic photothermal and synergic antibacterial hydrogel was designed via one-pot approach to cope with full-thickness skin wound infection. In this work, the mixture of silver‑sodium lignin sulfonate nanoparticles (Ag-SLS NPs) and polypyrrole-polydopamine nanoparticles (PPy-PDA NPs) for the first time as synergic photothermal agent was introduced into poly (ethylene glycol) diacrylate (PEGDA) to form Ag-SLS/PPy-PDA@PEGDA hydrogel. Thanks to the near-infrared light into heat conversion capacity of both Ag and PPy-PDA NPs, the formed hydrogel shows ultrahigh photothermal activity, and outstanding antibacterial activity to both Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria in vitro. Additionally, in vivo assay indicates that the hydrogel has outstanding long-term antibacterial effect due to the photothermal sterilization along with Ag ions release. Overall, the dual-synergic photothermal and antibacterial effects of the Ag-SLS/PPy-PDA@PEGDA hydrogel could highly accelerate infection wound healing, and thus has great potential to be used for tissue engineering.

Breast Cancer Cell Membrane Camouflaged Lipid Nanoparticles for Tumor-Targeted NIR-II Phototheranostics

Photoacoustic imaging and photothermal therapy that employ organic dye in the second near-infrared window (NIR-II) became an attractive theranostical strategy for eliminating solid tumors, in which IR1048 was previously reported to be a good candidate. However, the further biomedical application of IR1048 was blocked by its poor water-solubility and lack of tumor-targeting. To solve this problem, liposome camouflaged with 4T1 cell membrane fragments was employed to encapsulate IR1048 (thereafter called MLI), and its application for photoacoustic and thermo-imaging and photothermal therapy were explored in vitro and in vivo. The results showed that MLI exhibited spherical morphology around 92.55 ± 5.41 nm coated by monolayer adventitial fragments, and uniformly dispersed in PBS with high loading efficiency and encapsulation efficiency to IR1048. In addition, both free IR1048 and MLI presented strong absorption in NIR-II, and upon 1064 nm laser irradiation the MLI showed awesome photothermal performance that could rapidly elevate the temperature to 50.9 °C in 6 min. Simultaneously, phantom assay proved that MLI could dramatically enhance the photoacoustic amplitudes by a linear concentration-dependent way. Moreover, either flow cytometry or confocal analysis evidenced that MLI was the most uptaked by 4T1 cells among other melanoma B16 cells and Hek293 cells and coexist of IR1048 and 1064 nm laser irradiation were indispensable for the photothermal cytotoxicity of MLI that specifically killed 96.16% of 4T1 cells far outweigh the B16 cells while hardly toxic to the Hek293 normal cells. Furthermore, PA imaging figured out that 4 h post tail-vein injection of MLI was the best time to give 1064 nm irradiation to conduct the photothermal therapy when the average tumor-accumulation of MLI achieved the highest. In the NIR-II photothermal therapy, MLI could significantly inhibit the tumor growth and almost ablated the tumors with slight body weight variation and the highest average life span over the therapy episode and caused no damage to the normal organs. Hence, MLI could pave the way for further biomedical applications of IR-1048 by homologous tumor-targeting and dual-modal imaging directed NIR-II accurate photothermal therapy with high efficacy and fine biosafety.

Switching the NIR upconversion of nanoparticles for the orthogonal activation of photoacoustic imaging and phototherapy

Phototheranostics based on upconversion nanoparticles (UCNPs) offer the integration of imaging diagnostics and phototherapeutics. However, the programmable control of the photoactivation of imaging and therapy with minimum side effects is challenging due to the lack of ideal switchable UCNPs agents. Here we demonstrate a facile strategy to switch the near infrared emission at 800 nm from rationally designed UCNPs by modulating the irradiation laser into pulse output. We further synthesize a theranostic nanoagent by combining with a photosensitizer and a photoabsorbing agent assembled on the UCNPs. The orthogonal activation of in vivo photoacoustic imaging and photodynamic therapy can be achieved by altering the excitation modes from pulse to continuous-wave output upon a single 980 nm laser. No obvious harmful effects during photoexcitation was identified, suggesting their use for long-term imaging-guidance and phototherapy. This work provides an approach to the orthogonal activation of imaging diagnostics and photodynamic therapeutics.

A-DA'D-A Structured Organic Phototheranostics for NIR-II Fluorescence/Photoacoustic Imaging-Guided Photothermal and Photodynamic Synergistic Therapy

Multimodal imaging-guided combinational phototherapies triggered by a single near-infrared (NIR) laser are highly desirable. However, their development is still a big challenge. Herein, we have developed an "acceptor-donor-acceptor'-donor-acceptor" structured organic phototheranostics (Y16-Pr) with strong light-harvesting ability in the NIR region. After being modified with polyethylene glycol (PEG), the obtained biocompatible nanoparticles (Y16-Pr-PEG NPs) could conduct NIR-II fluorescence imaging (FLI) and photoacoustic imaging (PAI) and perform photothermal therapy (PTT) and photodynamic therapy (PDT) simultaneously. Notably, Y16-Pr-PEG NPs showed an impressive photothermal conversion efficiency (PCE) of 82.4% under 808 nm laser irradiation. The irradiated NPs could also produce hydroxyl radicals (•OH) and singlet oxygen (¹O₂) for type I and type II PDT, respectively. In vivo and in vitro experiments revealed that the Y16-Pr-PEG NPs significantly inhibit tumor cell growth without apparent toxic side effects under laser irradiation. Overall, the single-laser-triggered multifunctional phototheranostic Y16-Pr-PEG NPs can achieve NIR-II FLI/PAI-guided synergistic PTT/PDT against tumors.

Photothermal conversion performance and acid-induced aggregation of PLNP-Bi2S3 composite nanoplatforms

Poly(sodium 4-styrenesulfonate) (PSS) molecule modified PLNP-Bi₂S₃ composite nanoplatforms were constructed by using polyvinylpyrrolidone (PVP) modified Bi₂S₃ nanoparticles (∼4.6 nm) as a photothermal agent and hexadecyl trimethyl ammonium bromide (CTAB) coated Zn₂Ga_2.98Ge_0.75O₈:Cr_0.02³⁺ (ZGGO:Cr³⁺@CTAB) persistent luminescence nanoparticles (PLNPs) through electrostatic adsorption. It is found that the above composite nanoplatforms have excellent laser-irradiation thermal stability and good photothermal conversion performance. The measured photothermal conversion efficiency is ∼44%, which is higher than that (∼37%) of the PLNP-GNR (gold nanorod) composite nanoplatforms. Meanwhile, PSS modified PLNP-Bi₂S₃ composite nanoplatforms exhibited good solution dispersibility in blood and normal tissue environments. While reaching tumor sites, the above composite nanoplatforms can be rapidly accumulated in cancer cells with acidic environments. This pH-responsive acid-induced aggregation can be ascribed to the chemical reaction induced by the protonation of PSS modified PLNP-Bi₂S₃ composite nanoplatforms with a negatively charged surface in the acidic environments. Our results suggest that PSS modified PLNP-Bi₂S₃ composite nanoplatforms might be applied to precision diagnosis and therapy of deep-tissue tumors.

Exogenous Contrast Agents in Photoacoustic Imaging: An In Vivo Review for Tumor Imaging

The field of cancer theranostics has grown rapidly in the past decade and innovative ‘biosmart’ theranostic materials are being synthesized and studied to combat the fast growth of cancer metastases. While current state-of-the-art oncology imaging techniques have decreased mortality rates, patients still face a diminished quality of life due to treatment. Therefore, improved diagnostics are needed to define in vivo tumor growths on a molecular level to achieve image-guided therapies and tailored dosage needs. This review summarizes in vivo studies that utilize contrast agents within the field of photoacoustic imaging—a relatively new imaging modality—for tumor detection, with a special focus on imaging and transducer parameters. This paper also details the different types of contrast agents used in this novel diagnostic field, i.e., organic-based, metal/inorganic-based, and dye-based contrast agents. We conclude this review by discussing the challenges and future direction of photoacoustic imaging.

Polymeric micelles-based nanoagents enable phototriggering combined chemotherapy and photothermal therapy with high sensitivity

A new type of polymeric nanomicelles-based nanoagent (denoted as PT@MFH hereafter) capable of highly sensitively releasing chemotherapeutic drug paclitaxel (PTX) upon triggering of near-infrared laser was developed by encapsulating PTX...

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

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

Combined Photothermotherapy and Chemotherapy of Oral Squamous Cell Carcinoma Guided by Multifunctional Nanomaterials Enhanced Photoacoustic Tomography

Background

Squamous cell carcinoma of the head and neck is the sixth most common cancer worldwide, with 40% occurring in the oral cavity. Although the level of early diagnosis and treatment of OSCC has improved significantly, the five-year survival rate of advanced patients remains unsatisfactory. However, the main challenges before us are how to get an early and accurate diagnosis and how to formulate effective treatment. Nanoparticle-based chemo-photothermal therapy has proven to be a promising non-invasive approach to treating oral squamous cell carcinoma treatment.

Methods

In this study, we tried to design and synthesize multifunctional hyaluronic acid (HA) modified gold nanorods/mesoporous silica-based nanoparticles loaded with doxorubicin hydrochloride (DOX) for photoacoustic imaging (PAI) guided cooperative chemo-photothermal therapy.

Results

The resultant nanocomposite shows favorable biocompatibility, relatively low cytotoxicity, ideal drug loading capability and strong PAI signals. In addition, they showed an excellent photothermal conversion efficiency of 49.02% for photothermal therapy (PTT). Moreover, in vivo and in vitro experiments have shown that synergistic chemo-photothermal therapy has better therapeutic effects than chemotherapy alone or PTT (P < 0.05). After being injected into the CAL-27 tumor-bearing mice, the DOX-AuNRs@mSiO₂-HA nanoparticles could accumulate rapidly at the tumor sites and achieve complete ablation of tumors when combined with near-infrared laser irradiation, without obvious side effects on normal tissues.

Conclusion

Our research provides a solid demonstration of the potential of DOX-AuNRs@mSiO₂-HA as a multifunctional platform in PAI-guided photothermal chemotherapy for oral squamous cell carcinoma.

Semiconducting polymer nano-radiopharmaceutical for combined radio-photothermal therapy of pancreatic tumor

Background

Pancreatic ductal adenocarcinoma (PDAC) is a devastatingly malignant tumor with a high mortality. However, current strategies to treat PDAC generally have low efficacy and high side-effects, therefore, effective treatment against PDAC remains an urgent need.

Results

We report a semiconducting polymer nano-radiopharmaceutical with intrinsic photothermal capability and labeling with therapeutic radioisotope ¹⁷⁷Lu (¹⁷⁷Lu-SPN-GIP) for combined radio- and photothermal therapy of pancreatic tumor. ¹⁷⁷Lu-SPN-GIP endowed good stability at physiological conditions, high cell uptake, and long retention time in tumor site. By virtue of combined radiotherapy (RT) and photothermal therapy (PTT), ¹⁷⁷Lu-SPN-GIP exhibited enhanced therapeutic capability to kill cancer cells and xenograft tumor in living mice compared with RT or PTT alone. More importantly, ¹⁷⁷Lu-SPN-GIP could suppress the growth of the tumor stem cells and reverse epithelial mesenchymal transition (EMT), which may greatly reduce the occurrence of metastasis.

Conclusion

Such strategy we developed could improve therapeutic outcomes over traditional RT as it is able to ablate tumor with relatively lower doses of radiopharmaceuticals to reduce its side effects.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01083-0.

Conjugated Polymers: Optical Toolbox for Bioimaging and Cancer Therapy

Conjugated polymers (CPs) are capable of coordinating the electron coupling phenomenon to bestow powerful optoelectronic features. The light-harvesting and light-amplifying properties of CPs are extensively used in figuring out the biomedical issues with special emphasis on accurate diagnosis, effective treatment, and precise theranostics. This review summarizes the recent progress of CP materials in bioimaging, cancer therapeutics, and introduces the design strategies by rationally tuning the optical properties. The recent advances of CPs in bioimaging applications are first summarized and the challenges to clear the future directions of CPs in the respective area are discussed. In the following sections, the focus is on the burgeoning applications of CPs in phototherapy of the tumor, and illustrates the underlying photo-transforming mechanism for further molecular designing. Besides, the recent progress in the CPs-assistant drug therapy, mainly including drug delivery, gene therapeutic, the optical-activated reversion of tumor resistance, and synergistic therapy has also been discussed elaborately. In the end, the potential challenges and future developments of CPs on cancer diagnosis and therapy are also illuminated for the improvement of optical functionalization and the promotion of clinical translation.

Temperature-Feedback Nanoplatform for NIR-II Penta-Modal Imaging-Guided Synergistic Photothermal Therapy and CAR-NK Immunotherapy of Lung Cancer

In this study, to visually acquire all-round structural and functional information of lung cancer while performing synergistic photothermal therapy (PTT) and tumor-targeting immunotherapy, a theranostic nanoplatform that introduced upconversion nanoparticles (UCNPs) and IR-1048 dye into the lipid-aptamer nanostructrure (UCILA) is constructed. Interestingly, the IR-1048 dye grafted into the lipid bilayer can serve as the theranostic agent for photoacoustic imaging, optical coherence tomography angiography, photothermal imaging, and PTT in the second near infrared (NIR-II) window. In addition, loaded in the inner part of UCILA, UCNPs possess the superior luminescence property and high X-ray attenuation coefficient, which can act as contrast agents for computed tomography (CT) and thermo-sensitive up-conversion luminescence (UCL) imaging, enabling real-time tracking of metabolic activity of tumor and temperature-feedback PTT. Furthermore, under the complementary guidance of penta-modal imaging and an accurate monitoring of in situ temperature change during PTT, UCILA exhibits its excellent capability for ablating the lung tumor with minimal side effects. Meanwhile, synergistic CAR-NK immunotherapy is carried out specifically to eradicate any possible residual tumor cells after PTT. Therefore, the UCILA nanoplatform is demonstrated as a multifunctional theranostic agent for both penta-modal imaging and temperature-feedback PTT while conducting targeting immunotherapy of lung cancer.

Variable Molecular Weight Polymer Nanoparticles for Detection and Hyperthermia-Induced Chemotherapy of Colorectal Cancer

Simple Summary

The purpose of this work was to evaluate the development of polymer-based nanoparticles that can both generate heat and be used for fluorescence detection. The nanoparticles were used against luminescent colorectal cancer cells that were either sensitive or resistant to the chemotherapy drug, oxaliplatin. The fluorescence of the nanoparticles indicates that they are internalized within the cells for heat generation. Mild heating makes oxaliplatin-resistant cancer cells responsive to chemotherapy, and the nanoparticle-induced hyperthermia causes cell death in a few minutes, compared to classical bulk heating, which takes a few hours. Changes in the luminescence of the cancer cells can be used to determine the thermal dose induced by the nanoparticles, which may be correlated with the cell viability and therapeutic response.

Abstract

Oxaliplatin plays a significant role as a chemotherapeutic agent for the treatment of colorectal cancer (CRC); however, oxaliplatin-resistant phenotypes make further treatment challenging. Here, we have demonstrated that rapid (60 s) hyperthermia (42 °C), generated by the near-infrared stimulation of variable molecular weight nanoparticles (VMWNPs), increases the effectiveness of oxaliplatin in the oxaliplatin-resistant CRC cells. VMWNP-induced hyperthermia resulted in a higher cell death in comparison to cells exposed to chemotherapy at 42 °C for 2 h. Fluorescence from VMWNPs was observed inside cells, which allows for the detection of CRC. The work further demonstrates that the intracellular thermal dose can be determined using cell luminescence and correlated with the cell viability and response to VMWNP-induced chemotherapy. Mild heating makes oxaliplatin-resistant cancer cells responsive to chemotherapy, and the VMWNPs-induced hyperthermia can induce cell death in a few minutes, compared to classical bulk heating. The results presented here lay the foundation for photothermal polymer nanoparticles to be used for cell ablation and augmenting chemotherapy in drug-resistant colorectal cancer cells.

Second near-infrared photoactivatable biocompatible polymer nanoparticles for effective in vitro and in vivo cancer theranostics

Photoacoustic imaging (PAI)-guided photothermal therapy (PTT) has drawn considerable attention due to the deeper tissue penetration and higher maximum permissible exposure. However, current phototheranostic agents are greatly restricted by weak absorption in the second near-infrared (NIR-II, 1000-1700 nm) window, long-term toxicity, and poor photostability. In this report, novel organic NIR-II conjugated polymer nanoparticles (CPNs) based on narrow bandgap donor-acceptor BDT-TBZ polymers were developed for effective cancer PAI and PTT. Characterization data confirmed the high photothermal conversion efficiency, good photostability, excellent PAI performance, and superior biocompatibility of as-obtained CPNs. In addition, in vitro and in vivo tests demonstrated the efficient PTT effect of CPNs in ablating cancer cells and inhibiting tumor growth under 1064 nm laser irradiation. More importantly, the CPNs exhibited rapid clearance capability through the biliary pathway and negligible systematic toxicity. Thus, this work provides a novel organic theranostic nanoplatform for NIR-II PAI-guided PTT, which advances the future clinical translation of biocompatible and metabolizable conjugated nanomaterials in cancer diagnosis and therapy.

A biodegradable nano-photosensitizer with photoactivatable singlet oxygen generation for synergistic phototherapy

Photodynamic therapy (PDT) is a promising method for cancer therapy and also may initiate unexpected damages to normal cells and tissues. Herein, we develop a near-infrared (NIR) light-activatable nanophotosensitizer, which shows negligible phototoxicity before photoactivation to improve the specificity of PDT. The nanophotosensitizer is prepared by indocyanine green carboxylic (ICG), Chlorin e6 (Ce6), and biodegradable poly (lactic acid) (PLA) and poly (lactic-co-glycolic acid) (PLGA), and all these materials have been approved by the Food and Drug Administration. Initially the phototoxicity of Ce6 is effectively inhibited by ICG through fluorescence resonance energy transfer (FRET). Upon 808 nm laser activation, ICG generate hyperthermia for photothermal therapy (PTT) and simultaneously is degraded due to the inherently poor photostability. The FRET is disrupted and followed by the recovery of phototoxicity of Ce6 for PDT. We investigated the photoactivation and the resulting phototherapy by cellular assays and mouse models, which indicate a superior synergistic treatment effect and selective PDT activated by near-infrared 808 nm light. This study presents a promising strategy for activatable and synergistic phototherapy with minimal damage to normal tissues.

A Systematic Strategy of Combinational Blow for Overcoming Cascade Drug Resistance via NIR-Light-Triggered Hyperthermia

A systematic combination strategy is proposed for overcoming cisplatin resistance using near-infrared (NIR)-light-triggered hyperthermia. A new photothermal polymer DAP-F is complexed with a reduction-sensitive amphiphilic polymer P1 to form F-NPs with photothermal effect. Subsequently, to build the final nanosystem F-Pt-NPs, F-NPs are combined with Pt-NPs, which are obtained by encapsulating a Pt(IV) prodrug with P1. Mild hyperthermia (43 °C), generated from F-Pt-NPs induced by an 808 nm NIR laser, have various effects such as: i) enhancing the cellular membrane permeability to promote the uptake of drugs; ii) activating cisplatin by accelerating the glutathione consumption; iii) increasing the Pt-DNA adducts formation and possibly the formation of a portion of irreparable Pt-DNA interstrand crosslinks, thereby inhibiting the repair of DNA. In vitro, it is found that even on cisplatin-resistant A549DDP cells, the IC50 of F-Pt-NPs (43 °C) is only 7.0 × 10-6 m Pt mL-1 . In vivo, on a patient-derived xenograft model of multidrug resistant lung cancer, the efficacy of the F-Pt-NPs (43 °C) treatment group shows a tumor inhibition rate of 94%. Taken together, here, an important perspective of resolving cascade drug resistance with the assistance of mild hyperthermia triggered by NIR light is presented, which can be of great significance for clinic translation.

Measuring Cellular Uptake of Polymer Dots for Quantitative Imaging and Photodynamic Therapy

There is a great deal of interest in the development of nanoparticles for biomedicine. The question of how many nanoparticles are taken up by cells is important for biomedical applications. Here, we describe a fluorescence method for the quantitative measurement of the cellular uptake of polymer dots (Pdots) and a further estimation of intracellular Pdots photosensitizer for fluorescence imaging and photodynamic therapy. The approach relies on the high brightness, excellent stability, minimal aggregation quenching, and metalloporphyrin doping properties of the Pdots. We correlated the single-cell fluorescence brightness obtained from fluorescence spectrometry, confocal microscopy, and flow cytometry with the number of endocytosed Pdots, which was validated by inductively coupled plasma mass spectrometry. Our results indicated that, on average, ∼1.3 million Pdots were taken up by single cells that were incubated for 4 h with arginine 8-Pdots (40 μg/mL, ∼20 nm diameter). The absolute number of endocytosed Pdots of individual cells could be estimated from confocal microscopy by comparing the single-cell brightness with the average intensity. Furthermore, we investigated the cell viability as a result of an intracellular Pdots photosensitizer, from which the half maximal inhibitory concentration was determined to be ∼7.2 × 10⁵ Pdots per cell under the light dose of 60 J/cm². This study provides an effective method for quantifying endocytosed Pdots, which can be extended to investigate the cellular uptake of various conjugated polymer carriers in biomedicine.

Recent advances in semiconducting polymer dots as optical probes for biosensing

This review mainly summarized the recent results that used bright polymer dots (Pdots) for the detection of different analytes such as reactive oxygen species (ROS), metal ions, pH values, and a variety of biomolecules.

Passively Mode-Locked Operations Induced by Semiconducting Polymer Nanoparticles and a Side-Polished Fiber

Semiconducting polymer nanoparticles (SPNs) possess many special photophysical and chemical properties. However, little research has been done on the potential of SPNs in laser technology. In this work, we present the ultrafast pulses generation at 1.5 and 2 μm through proposing the deposition of SPNs onto a side-polished fiber (SPF) platform as the nonlinear optical modulator. SPNs are designed and prepared through a combination of density functional theory and nanoreprecipitation method. The prepared SPNs not only exhibit strong linear absorption but also has nonlinear saturable absorption characteristics. Once SPF-SPNs saturable absorber (SA) is integrated into the laser cavity, ultrafast lasers of 1.5 and 2 μm can be achieved with high performance. Our results show that SAs based on the SPNs and SPF are promising nonlinear optical modulators for broadband ultrafast pulse generation.

Facile Synthesis of Melanin-Dye Nanoagent for NIR-II Fluorescence/Photoacoustic Imaging-Guided Photothermal Therapy

Background

Laryngeal cancer is the second most common type of primary epithelial malignant tumor in the head and neck region, and the development of therapies that are more precise, efficient, and safe is necessary to preserve patient speech and swallowing functions as much as possible. Multi-modal imaging-guided photothermal therapy (PTT) can precisely delineate tumors, monitor the real-time accumulation of photothermal agents at the tumor site, accurately select the optimal region for irradiation, and predict the best time for laser treatment. Compared with exogeneous photothermal agents, endogenous melanin materials have better biosafety in vivo, in terms of native biocompatibility and biodegradability, as well as good near-infrared (NIR) absorbance. An NIR-II dye can be attached to melanin via a facile method, and applying a melanin-dye-based nanoprobe could be an excellent choice for the elimination of superficial laryngeal cancer while avoiding total laryngectomy.

Methods

In this work, a promising nanoprobe was constructed using a facile EDC/NHS strategy involving an NIR-II dye and melanin nanoparticles.

Results

The nanoprobe exhibited good water solubility, dispersibility, strong NIR-II fluorescence and photoacoustic (PA) signals, and higher photothermal performance. Cellular studies showed that the nanoprobe had low toxicity, excellent biocompatibility, and significantly enhanced imaging properties. After the nanoprobe was intravenously injected into Hep-2 laryngeal xenografts, superior dual-modal images were obtained at various time points, which revealed that the optimal photothermal treatment time was 8 h. Subsequently, PTT was carried out in vivo, and laryngeal tumors were completely eliminated after laser irradiation without any obvious side effects.

Conclusion

These results indicate the immense potential of nanoprobes for the NIR-II fluorescence/PA imaging-guided photothermal therapy of laryngeal cancer.

NIR/photoacoustic imaging of multitype gallbladder cancer using carboxyl/amino functionalized polymer dots

Gallbladder cancer has high incidence and mortality and a low early diagnosis rate and requires rapid and efficient diagnosis. Herein, carboxyl/amino functionalized polymer dots (Pdots) were designed to enhance cellular internalization and tumor accumulation. The prepared Pdots were 40-50 nm in diameter, contained no toxic metal, exhibited long circulation time and high stability, and produced strong NIR emission and photoacoustic signals. Different cellular uptake and distribution of functionalized Pdots in eight gallbladder cell lines were quantitatively investigated using flow cytometry and super-resolution microscopy. In vivo NIR fluorescence imaging showed that the functional Pdots had high accumulation in the tumor after 30 minutes of injection and remained there for up to 6 days. In addition, photoacoustic imaging found that the abundant blood vessels around the tumor microenvironment and Pdots entered the tumor through the blood vessels. Furthermore, a high heterogeneity of vascular networks was visualized in real-time and high resolution by probe-based confocal laser endomicroscopy imaging. These results offer a new avenue for the development of functional Pdots as a probe for multi-modal and multi-scale imaging of gallbladder cancer in small animals.

Thermosensitive Polymer Dot Nanocomposites for Trimodal Computed Tomography/Photoacoustic/Fluorescence Imaging-Guided Synergistic Chemo-Photothermal Therapy

Precision delivery of theranostic agents to the tumor site is essential to improve their diagnostic and therapeutic efficacy and concurrently minimize adverse effects during treatment. In this study, a novel concept of near-infrared (NIR) light activation of conjugated polymer dots (Pdots) at thermosensitive hydrogel nanostructures is introduced for multimodal imaging-guided synergistic chemo-photothermal therapy. Interestingly, owing to the attractive photothermal conversion efficiency of Pdots, the Pdots@hydrogel as theranostic agents is able to undergo a controllable softening or melting state under the irradiation of NIR laser, resulting in light-triggered drug release in a controlled way and concurrently hydrogel degradation. Besides, the novel Pdots@hydrogel nanoplatform can serve as the theranostic agent for enhanced trimodal photoacoustic (PA)/computed tomography (CT)/fluorescence (FL) imaging-guided synergistic chemo-photothermal therapy of tumors. More importantly, the constructed intelligent nanocomposite Pdots@hydrogel exhibits excellent biodegradability, strong NIR absorption, bright PA/CT/FL signals, and superior tumor ablation effect. Therefore, the concept of a light-controlled multifunctional Pdots@hydrogel that integrates multiple diagnostic/therapeutic modalities into one nanoplatform can potentially be applied as a smart nanotheranostic agent to various perspectives of personalized nanomedicine.

Dual-Mode Superresolution Imaging Using Charge Transfer Dynamics in Semiconducting Polymer Dots

In a conjugated polymer-based single-particle heterojunction, stochastic fluctuations of the photogenerated hole population lead to spontaneous fluorescence switching. We found that 405 nm irradiation can induce charge recombination and activate the single-particle emission. Based on these phenomena, we developed a novel class of semiconducting polymer dots that can operate in two superresolution imaging modes. The spontaneous switching mode offers efficient imaging of large areas, with <10 nm localization precision, while the photoactivation/deactivation mode offers slower imaging, with further improved localization precision (ca. 1 nm), showing advantages in resolving small structures that require high spatial resolution. Superresolution imaging of microtubules and clathrin-coated pits was demonstrated, under both modes. The excellent localization precision and versatile imaging options provided by these nanoparticles offer clear advantages for imaging of various biological systems.

Facile Preparation of Phthalocyanine-Based Nanodots for Photoacoustic Imaging and Photothermal Cancer Therapy In Vivo

The development of near-infrared (NIR)-absorbing nanoagents for personalized multifunctional phototheranostics has attracted considerable attention in the past decade. Recently, the organic nanomaterials with good biosafety are considered as promising phototheranostic agents, while their facile synthesis remains challenging. Inspired by the preparation of carbon nanodots, we fabricate the NIR-absorbing phthalocyanine-based nanodots (ZnPc-NDs) using a facile method for multifunctional phototheranostics. The significant aggregation of phthalocyanines in nanodots induces a complete fluorescence quenching, which affords a high photothermal conversion efficiency (η = 45.7%). The ZnPc-NDs disperse very well in water media with an average diameter around 80 nm. Further conjugation of biotin on the surface of ZnPc-NDs affords tumor-targeting phthalocyanine nanodots (ZnPc-BT). The ZnPc-BT are demonstrated with favorable biocompatibility, intense photoacoustic signals, high tumor accumulation, and effective tumor suppression in vivo. This Article provides a new insight for further developing nanomedicines with imaging and therapeutic functions to treat cancers precisely and effectively.

Single-Photomolecular Nanotheranostics for Synergetic Near-Infrared Fluorescence and Photoacoustic Imaging-Guided Highly Effective Photothermal Ablation

Multi-modality imaging-guided cancer therapy is considered as a powerful theranostic platform enabling simultaneous precise diagnosis and treatment of cancer. However, recently reported multifunctional systems with multiple components and sophisticate structures remain major obstacles for further clinical translation. In this work, a single-photomolecular theranostic nanoplatform is fabricated via a facile nanoprecipitation strategy. By encapsulating a semiconductor oligomer (IT-S) into an amphiphilic lipid, water-dispersible IT-S nanoparticles (IT-S NPs) are prepared. The obtained IT-S NPs have a very simple construction and possess ultra-stable near-infrared (NIR) fluorescence (FL)/photoacoustic (PA) dual-modal imaging and high photothermal conversion efficiency of 72.3%. Accurate spatiotemporal distribution profiles of IT-S NPs are successfully visualized by NIR FL/PA dual-modal imaging. With the comprehensive in vivo imaging information provided by IT-S NPs, tumor photothermal ablation is readily realized under precise manipulation of laser irradiation, which greatly improves the therapeutic efficacy without any obvious side effects. Therefore, the IT-S NPs allow high tumor therapeutic efficacy under the precise guidance of FL/PA imaging techniques and thus hold great potential as an effective theranostic platform for future clinical applications.

Rational design of semiconducting polymer brushes as cancer theranostics

Photonic theranostics (PTs) generally contain optical agents for the optical sensing of biomolecules and therapeutic components for converting light into heat or chemical energy. Semiconducting polymer nanoparticles (SPNs) as advanced PTs possessing good biocompatibility, stable photophysical properties, and sensitive and tunable optical responses from the ultraviolet to near-infrared (NIR) II window (300-1700 nm) have recently aroused great interest. Although semiconducting polymers (SPs) with various building blocks have been synthesized and developed to meet the demands of biophotonic applications, most of the SPNs were made by a nanoprecipitation method that used amphiphilic surfactants to encapsulate SPs. Such binary SP micelles usually exhibit weakened photophysical properties of SPs and undergo dissociation in vivo. SP brushes (SPBs) are products of functional post-modification of SP backbones, which endows unique features to SPNs (e.g. enhanced optical properties and multiple chemical reaction sites for the conjunction of organic/inorganic imaging agents and therapeutics). Furthermore, the SPB-based SPNs can be highly stable due to supramolecular self-assembly and/or chemical crosslinking. In this review, we highlight the recent progress in the development of SPBs for advanced theranostics.

Conjugated polymer nano-systems for hyperthermia, imaging and drug delivery

Hyperthermia has shown tremendous therapeutic efficiency in the treatment of cancer due to its controllability, minimal invasiveness and limited side effects compared to the conventional treatment techniques like surgery, radiotherapy and chemotherapy. To improve the precision of hyperthermia specifically to a tumor location, near infra-red (NIR) light activatable inorganic metal nanoparticles have served as effective photothermal therapy materials, but toxicity and non-biodegradability have limited their clinical applications. Conjugated polymer nanoparticles have overcome these limitations and are emerging as superior photothermal materials owing to their excellent light harvesting nature, biocompatibility and tunable absorption properties. In this review we focus on the development of organic conjugated polymers (polyaniline, polypyrrole, polydopamine etc.) and their nanoparticles, which have broad NIR absorption. Such materials elicit photothermal effects upon NIR stimulation and may also serve as carriers for delivery of therapeutic and contrast agents for combined therapy. Subsequently, the emergence of donor-acceptor based semiconducting polymer nanoparticles with strong absorbance that is tunable across the NIR have been shown to eradicate tumors by either hyperthermia alone or combined with other therapies. The design of multifunctional polymer nanoparticles that absorb near- or mid- infrared light for heat generation, as well as their diagnostic abilities for precise biomedical applications are highlighted.

Design of superior phototheranostic agents guided by Jablonski diagrams

This review summarizes how Jablonski diagrams guide the design of advanced organic optical agents and improvement of disease phototheranostic efficacies.

Mitochondrion-targeting chemiluminescent ternary supramolecular assembly for in situ photodynamic therapy

A new ternary supramolecular system can locate at mitochondria and produce chemiluminescence for in situ photodynamic therapy.

Organic semiconducting polymer amphiphile for near-infrared-II light-triggered phototheranostics

Development of near-infrared-II (NIR-II) light responsive nano-agents with high photothermal stability, high photothermal conversion efficiency (PCE), and excellent biocompatibility for photoacoustic (PA) imaging-guided photothermal therapy (PTT) is of tremendous significance. In spite of the superiority of organic semiconducting polymer nanoparticles (OSPNs) in PA imaging-guided PTT, the limited absorption in the first NIR (NIR-I) window and metastable nanostructure of OSPNs resulting from commonly used preparation methods based on nanoprecipitation or reprecipitation compromise their in vivo phototheranostic performance. Herein we design and synthesize a novel NIR-II absorbing organic semiconducting polymer amphiphile (OSPA) to enhance the structural stability of OSPNs. With prominent optical properties, low toxicity, and a suitable size, OSPA not only efficiently labels and kills cancer cells under NIR-II irradiation but also accumulates at the tumor of living mice upon intravenous injection, allowing efficient NIR-II light-triggered phototheranostics toward tumor. The developed OSPA has promising potential for fabricating multifunctional nanoplatforms to enable multimodal theranostics.

Biodegradable π-Conjugated Oligomer Nanoparticles with High Photothermal Conversion Efficiency for Cancer Theranostics

We developed a biodegradable photothermal therapeutic (PTT) agent, π-conjugated oligomer nanoparticles (F8-PEG NPs), for highly efficient cancer theranostics. By exploiting an oligomer with excellent near-infrared (NIR) absorption, the nanoparticles show a high photothermal conversion efficiency (PCE) up to 82%, surpassing those of reported inorganic and organic PTT agents. In addition, the oligomer nanoparticles show excellent photostability and good biodegradability. The F8-PEG NPs are also demonstrated to have excellent biosafety and PTT efficacy both in vitro and in vivo. This contribution not only proposes a promising oligomer-based PTT agent but also provides insight into developing highly efficient nanomaterials for cancer theranostics.

Recent Progress on Near-Infrared Photoacoustic Imaging: Imaging Modality and Organic Semiconducting Agents

Over the past few decades, the photoacoustic (PA) effect has been widely investigated, opening up diverse applications, such as photoacoustic spectroscopy, estimation of chemical energies, or point-of-care detection. Notably, photoacoustic imaging (PAI) has also been developed and has recently received considerable attention in bio-related or clinical imaging fields, as it now facilitates an imaging platform in the near-infrared (NIR) region by taking advantage of the significant advancement of exogenous imaging agents. The NIR PAI platform now paves the way for high-resolution, deep-tissue imaging, which is imperative for contemporary theragnosis, a combination of precise diagnosis and well-timed therapy. This review reports the recent progress on NIR PAI modality, as well as semiconducting contrast agents, and outlines the trend in current NIR imaging and provides further direction for the prospective development of PAI systems.