Photoacoustic (PA) imaging and photothermal therapy (PTT) have attracted extensive attention in disease diagnosis and treatment. Although many exogenous contrast agents have been developed for PA ...imaging and PTT, the design guidelines to amplify their imaging and therapy performances remain challenging and are highly demanded. Semiconducting polymer nanoparticles (SPNs) composed of polymers with π‐electron delocalized backbones can be designed to amplify their PA imaging and PTT performance, because of their clear structure–property relation and versatility in modifying their molecular structures to tune their photophysical properties. This review summarizes the recent advances in the photoacoustic imaging and photothermal therapy applications of semiconducting polymer nanoparticles with a focus on signal amplification and second near‐infrared (NIR‐II, 1000–1700 nm) construction. The strategies such as structure–property screening, fluorescence quenching, accelerated heat dissipation, and size‐dependent heat dissipation are first discussed to amplify the PA brightness of SPNs for in vivo PA. The molecular approaches to shifting the absorption of SPNs for NIR‐II PA imaging and PTT are then introduced so as to improve the tissue penetration depth for diagnosis and therapy. At last, current challenges and perspectives of SPNs in the field of imaging and therapy are discussed.
The recent advances in the photoacoustic imaging and photothermal therapy applications of semiconducting polymer nanoparticles (SPNs) with a focus on signal amplification and second near‐infrared (NIR‐II, 1000–1700 nm) construction are summarized, showing the great potential of SPNs in biomedical research.
Fluorescence imaging in the second near‐infrared (NIR‐II) window facilitated by aggregation‐induced emission luminogens (AIEgens) is an emerging research field. NIR‐II AIEgens overcome limitations ...imposed by penetration depth and fluorescence efficiency, offering high‐performance imaging with enhanced precision. Some reported NIR‐II AIEgens demonstrate capabilities for fluorescence and photoacoustic bimodal imaging, and fluorescence imaging guided photothermal therapy, which not only improves diagnosis accuracy but provides an efficient theranostic platform to accelerate preclinical translation as well. This minireview summarizes recent efforts on exploiting NIR‐II AIEgens with regard to molecular design strategies and bioapplications, and puts forward current challenges and promising prospects. This timely sketch should benefit the further exploitation of diverse and multifunctional NIR‐II AIEgens for a wide array of applications.
Fluorescence imaging facilitated by NIR‐II emissive aggregation‐induced emission luminogens (AIEgens) is an emerging research field. This minireview summarizes recent efforts on developing novel NIR‐II AIEgens in terms of molecular design strategies and bioapplications, and discusses current challenges and future prospects.
•Ultrasmall biodegradable nitride MXene quantum dots (Ti2N QDs) are prepared.•Ti2N QDs exhibit excellent PA and PTT performance in both NIR-I/II biowindows.•Ti2N QDs show appropriate degradation rate ...and excretion rate from the body.•The prepared QDs are promising for precision cancer treatment.
As a prominent member of two dimensional (2D) materials, MXenes have shown encouraging photophysical properties and so there is highly desirability to explore their phototherapeutic potential in cancer. Herein, we demonstrate a facile top-down strategy for the synthesis of nitride-based MXene, titanium nitride quantum dots (Ti2N QDs) in solution. With a size of around 5 nm, the obtained Ti2N QDs exhibit extraordinarily high photothermal conversion efficiency under laser irradiation in both first and second near-infrared (NIR) biowindows (NIR-I, 808 nm, 48.62%; and NIR-II, 1064 nm, 45.51%). In vitro and in vivo assessments demonstrate that the Ti2N QDs possess excellent biocompatibility, photoacoustic (PA) effect, and photothermal therapy (PTT) efficiency. Moreover, the Ti2N QDs showing obvious aggregation in tumors after 4 h post-injection, which enables facilitate PA imaging-guided PTT in both NIR-I/II biowindows without noticeable toxicity. Encouragingly, the Ti2N QDs with appropriate degradation property also show an applicable excretion rate from the body in vivo, which ensures sufficient stability in circulation to accomplish therapeutics roles and then can be smoothly discharged from the body after that. These results indicate the high potential of biodegradable Ti2N QDs in PA imaging-guided PTT in both NIR-I/II biowindows for precision cancer treatment.
With balanced spatial resolution, penetration depth, and imaging speed, photoacoustic computed tomography (PACT) is promising for clinical translation such as in breast cancer screening, functional ...brain imaging, and surgical guidance. Typically using a linear ultrasound (US) transducer array, PACT has great flexibility for hand-held applications. However, the linear US transducer array has a limited detection angle range and frequency bandwidth, resulting in limited-view and limited-bandwidth artifacts in the reconstructed PACT images. These artifacts significantly reduce the imaging quality. To address these issues, existing solutions often have to pay the price of system complexity, cost, and/or imaging speed. Here, we propose a deep-learning-based method that explores the Wasserstein generative adversarial network with gradient penalty (WGAN-GP) to reduce the limited-view and limited-bandwidth artifacts in PACT. Compared with existing reconstruction and convolutional neural network approach, our model has shown improvement in imaging quality and resolution. Our results on simulation, phantom, and
in vivo
data have collectively demonstrated the feasibility of applying WGAN-GP to improve PACT’s image quality without any modification to the current imaging set-up.
Abnormal H₂O₂ levels are closely related to many diseases, including inflammation and cancers. Herein, we simultaneously load HRP and its substrate, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic ...acid) (ABTS), into liposomal nanoparticles, obtaining a Lipo@HRP&ABTS optical nanoprobe for in vivo H₂O₂-responsive chromogenic assay with great specificity and sensitivity. In the presence of H₂O₂, colorless ABTS would be converted by HRP into the oxidized form with strong near-infrared (NIR) absorbance, enabling photoacoustic detection of H₂O₂ down to submicromolar concentrations. Using Lipo@HRP&ABTS as an H₂O₂-responsive nanoprobe, we could accurately detect the inflammation processes induced by LPS or bacterial infection in which H₂O₂ is generated. Meanwhile, upon systemic administration of this nanoprobe we realize in vivo photoacoustic imaging of small s.c. tumors (∼2 mm in size) as well as orthotopic brain gliomas, by detecting H₂O₂ produced by tumor cells. Interestingly, local injection of Lipo@HRP&ABTS further enables differentiation of metastatic lymph nodes from those nonmetastatic ones, based on their difference in H₂O₂ contents. Moreover, using the H₂O₂-dependent strong NIR absorbance of Lipo@HRP&ABTS, tumor-specific photothermal therapy is also achieved. This work thus develops a sensitive H₂O₂-responsive optical nanoprobe useful not only for in vivo detection of inflammation but also for tumor-specific theranostic applications.
In recent years, people have been actively exploring new imaging methods with high biological imaging performance because the clinical image definition and depth in vivo cannot meet the requirements ...of early diagnosis and prognosis. Based on the traditional near-infrared region I (NIR-I), the molecular probe of the near-infrared region II (NIR-II) is further explored and developed. In the NIR-II region due to the wavelength is longer than the NIR-I region can effectively reduce the molecular scattering, optical absorption of the organization, the organization of spontaneous fluorescence negligible, thus the NIR-II Fluorescence imaging (FI) can get deeper penetration depth, higher signal-to-background ratio (SBR) and better spatiotemporal resolution, FI in NIR-II region are an important and rapidly developing research region for future imaging. In the NIR-II fluorophore, small organic molecule fluorophore has attracted much attention because of its good biocompatibility and good pharmacokinetic properties. In this review, we briefly introduced the existing NIR-II organic small molecule fluorophores, and introduced the existing relatively mature methods for improving quantum yield and water solubility, and the small molecule dyes on FI of various improvement methods, also briefly introduces the small molecules of photoacoustic imaging (PAI), and a brief introduction of imaging-guided surgery (IGS) for some small organic molecules, finally, a reasonable prospect is made for the development of small organic molecules.
Display omitted
Nonradiative decay invariably competes with radiative decay during the deexcitation process of matter. In the community of luminescence research, nonradiative decay has been deemed less attractive ...than radiative decay. However, all things in their being are good for something and so is nonradiative decay. As the molecular motion‐facilitated nonradiative decay (MMFND) effect is inevitable in photophysical processes, it provides a new avenue to convert the harvested light energy into exploitable forms by harnessing molecular motion. In many cases, active molecular motion enables thermal deactivation from excited states. In this Minireview, recent advances in photothermal and photoacoustic systems with MMFND character are summarized. We believe that this presentation of the rational engineering of molecular motion for efficient photothermal generation will deepen the understanding of the relationship between molecular motion and nonradiative decay and navigate people to rethink the positive aspects of nonradiative decay for the establishment of new light‐controllable techniques.
In the past few years, the molecular motion‐facilitated nonradiative decay (MMFND) effect has been widely used to develop efficient photothermal and photoacoustic systems. To give a timely summary of this emerging field, the present Minireview systematically highlights the underlying mechanism, molecular design principles, and advanced applications of photothermal transduction agents with flexible molecular groups.
Lysosome targetable carbon dots which can simultaneously generate 1O2, OH and heat under 635 nm laser irradiation were prepared, their applications in photothermal/photodynamic synergistic cancer ...therapy and photoacoustic/two-photon excited fluorescence imaging were demonstrated.
Display omitted
•Carbon dots with lysosome targeting ability was prepared.•The carbon dots exhibited negligible toxicity.•The multimodality imaging of carbon dots could be applied for diagnosis.•A highly efficient photothermal-photodynamic phototherapy of cancer was performed.
Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT) holds great potential for efficient cancer therapy by inducing reactive oxygen species (ROS) or heat into tumor. Nevertheless, PDT or PTT suffers from some limitations, e.g., PTT requires long-time and high-power laser irradiation to generate enough heat, while the hypoxia microenvironment of tumor and the limit diffuse distance of ROS hamper the efficacy of oxygen-dependent PDT. Here we reported the carbon dots (CDs) which could simultaneously generate singlet oxygen (1O2), hydroxyl radical (OH), and heat under a 635 nm laser irradiation, with a 1O2 generation quantum yield of 5.7% and photothermal conversion efficiency of 73.5% (the highest thus far for CDs). Significantly, the CDs can selectively accumulate in lysosome, which is an ideal organelle for phototherapy because of its key role in sustaining cellular activity and stability. Moreover, the CDs present one-photon excited (OPE) and two-photon excited (TPE) fluorescence, and excellent photoacoustic (PA) imaging capability. Combining the good biocompatibility, the as-prepared CDs was served as multi-functional phototheranostic agent for synergistic PA/fluorescence imaging, and PDT/PTT.
Combination of photodynamic therapy (PDT) and photothermal therapy (PTT) generally requires different components to build a composite irradiated with different excitation lights. One component ...photoactive agent for enhanced combination of PDT and PTT under the excitation of a single wavelength light source is more urgent in tumor phototherapy via adjusting spatial arrangement of photoactive units. Herein, porphyrin-based covalent organic framework nanoparticles (COF-366 NPs) were synthesized to control the orderly spatial arrangement of the photoactive building units and firstly used for antitumor therapy in vivo. COF-366 NPs provide the simultaneous therapy of PDT and PTT under a single wavelength light source with the monitoring of photoacoustic (PA) imaging, which makes the operation simpler and more convenient. COF-366 NPs had achieved good phototherapy effect even in the face of large tumors. The prepared multifunctional COF-366 NPs open up a new avenue to phototherapeutic materials and expand the application range of covalent organic framework.
PDF
