Organic Semiconducting Nanoparticles as Efficient Photoacoustic Agents for Lightening Early Thrombus and Monitoring Thrombolysis in Living Mice

Highly fluorescent hybrid nanofibers as potential nanofibrous scaffolds for studying cell-fiber interactions

In this study, we report on the fabrication of hybrid nanofibers for labeling and bioimaging applications. Our approach is involved for developing highly fluorescent nanofibers using a blend of polylactic acid, polyethyleneglycol, and perylenediimide dyes, through the solution blow spinning technique. The nanofibers are exhibited diameters ranging from 330 nm to 420 nm. Nanofibers showed excellent red and near-infrared fluorescence emissive properties in fluorescent spectroscopy. Moreover, the strong two-photon absorption phenomenon was observed for nanofibers under confocal microscopy. To assess the applicability of these fluorescent nanofibers in bioimaging settings, we employ two types of mammalian cells B16F1 melanoma cells and J774.A1 macrophages. Both cell types exhibit negligible cytotoxicity after 24 h incubation with the nanofibers, indicating the suitability of nanofibers for cell-based experiments. We also observe strong interactions between the nanofibers and cells, as evidenced by two major events: a) the acquisition of an elongated cellular morphology with the major cellular axis parallel to the nanofibers and b) the accumulation of actin filaments along the points of contact of the cells with the fibers. Our findings demonstrate the suitability of these newly developed fluorescent nanofibers in cell-based applications for guiding cellular behavior. We expect that these fluorescent nanofibers have the potential to serve as scaffold materials for long-time tracking of cell-fiber interactions in fluorescence microscopy.

Ultrasound-Based Micro-/Nanosystems for Biomedical Applications

Due to the intrinsic non-invasive nature, cost-effectiveness, high safety, and real-time capabilities, besides diagnostic imaging, ultrasound as a typical mechanical wave has been extensively developed as a physical tool for versatile biomedical applications. Especially, the prosperity of nanotechnology and nanomedicine invigorates the landscape of ultrasound-based medicine. The unprecedented surge in research enthusiasm and dedicated efforts have led to a mass of multifunctional micro-/nanosystems being applied in ultrasound biomedicine, facilitating precise diagnosis, effective treatment, and personalized theranostics. The effective deployment of versatile ultrasound-based micro-/nanosystems in biomedical applications is rooted in a profound understanding of the relationship among composition, structure, property, bioactivity, application, and performance. In this comprehensive review, we elaborate on the general principles regarding the design, synthesis, functionalization, and optimization of ultrasound-based micro-/nanosystems for abundant biomedical applications. In particular, recent advancements in ultrasound-based micro-/nanosystems for diagnostic imaging are meticulously summarized. Furthermore, we systematically elucidate state-of-the-art studies concerning recent progress in ultrasound-based micro-/nanosystems for therapeutic applications targeting various pathological abnormalities including cancer, bacterial infection, brain diseases, cardiovascular diseases, and metabolic diseases. Finally, we conclude and provide an outlook on this research field with an in-depth discussion of the challenges faced and future developments for further extensive clinical translation and application.

Deciphering Oxygen-Independent Augmented Photodynamic Oncotherapy by Facilitating the Separation of Electron-Hole Pairs

Developing Type-I photosensitizers provides an attractive approach to solve the dilemma of inadequate efficacy of photodynamic therapy (PDT) caused by the inherent oxygen consumption of traditional Type-II PDT and anoxic tumor microenvironment. The challenge for the exploration of Type-I PSs is to facilitate the electron transfer ability of photosensitization molecules for transforming oxygen or H2O to reactive oxygen species (ROS). Herein, we propose an electronic acceptor-triggered photoinduced electron transfer (a-PET) strategy promoting the separation of electron-hole pairs by marriage of two organic semiconducting molecules of a non-fullerene scaffold-based photosensitizer and a perylene diimide that significantly boost the Type-I PDT pathway to produce plentiful ROS, especially, inducing 3.5-fold and 2.5-fold amplification of hydroxyl (OH⋅) and superoxide (O2 -⋅) generation. Systematic mechanism exploration reveals that intermolecular electron transfer and intramolecular charge separation after photoirradiation generate a competent production of radical ion pairs that promote the Type-I PDT process by theoretical calculation and ultrafast femtosecond transient absorption (fs-TA) spectroscopy. By complementary tumor diagnosis with photoacoustic imaging and second near-infrared fluorescence imaging, this as-prepared nanoplatform exhibits fabulous photocytotoxicity in harsh hypoxic conditions and terrific cancer revoked abilities in living mice. We envision that this work will broaden the insight into high-efficiency Type-I PDT for cancer phototheranostics.

Light on Alzheimer's disease: from basic insights to preclinical studies

Alzheimer's disease (AD), referring to a gradual deterioration in cognitive function, including memory loss and impaired thinking skills, has emerged as a substantial worldwide challenge with profound social and economic implications. As the prevalence of AD continues to rise and the population ages, there is an imperative demand for innovative imaging techniques to help improve our understanding of these complex conditions. Photoacoustic (PA) imaging forms a hybrid imaging modality by integrating the high-contrast of optical imaging and deep-penetration of ultrasound imaging. PA imaging enables the visualization and characterization of tissue structures and multifunctional information at high resolution and, has demonstrated promising preliminary results in the study and diagnosis of AD. This review endeavors to offer a thorough overview of the current applications and potential of PA imaging on AD diagnosis and treatment. Firstly, the structural, functional, molecular parameter changes associated with AD-related brain imaging captured by PA imaging will be summarized, shaping the diagnostic standpoint of this review. Then, the therapeutic methods aimed at AD is discussed further. Lastly, the potential solutions and clinical applications to expand the extent of PA imaging into deeper AD scenarios is proposed. While certain aspects might not be fully covered, this mini-review provides valuable insights into AD diagnosis and treatment through the utilization of innovative tissue photothermal effects. We hope that it will spark further exploration in this field, fostering improved and earlier theranostics for AD.

Microbubble Biointerfacing by Regulation of the Platelet Membrane Surfactant Activity at the Gas-Liquid Interface for Acute Thrombosis Targeting

Biointerfacing nanomaterials with cell membranes has been successful in the functionalization of nanoparticles or nanovesicles, but microbubble functionalization remains challenging due to the unique conformation of the lipid monolayer structure at the gas-liquid interface that provides insufficient surfactant activity. Here, we describe a strategy to rationally regulate the surfactant activity of platelet membrane vesicles by adjusting the ratio of proteins to lipids through fusion with synthetic phospholipids (i.e., liposomes). A "platesome" with the optimized protein-to-lipid ratio can be assembled at the gas-liquid interface in the same manner as pulmonary surfactants to stabilize a microsized gas bubble. Platesome microbubbles (PMBs) inherited 61.4 % of the platelet membrane vesicle proteins and maintained the active conformation of integrin αIIbβ3 without the talin 1 for fibrin binding. We demonstrated that the PMBs had good stability, long circulation, and superior functionality both in vitro and in vivo. Moreover, by molecular ultrasound imaging, the PMBs provide up to 11.8 dB of ultrasound signal-to-noise ratio enhancement for discriminating between acute and chronic thrombi. This surface tension regulating strategy may provide a paradigm for biointerfacing microbubbles with cell membranes, offering a potential new approach for the construction of molecular ultrasound contrast agents for the diagnosis of different diseases.

A NIR-II Photoacoustic/NIR-IIa Fluorescent Probe for Targeted Imaging of Glioma under NIR-II Excitation

Fluorescence and photoacoustic (PA) imaging in the second near-infrared (NIR-II, 1000-1700 nm) window has garnered massive interest owing to high maximum permissible exposure of light, reduced autofluorescence, and improved deep penetration. However, active targeted NIR-II photoacoustic/NIR-IIa fluorescence imaging of glioma under NIR-II excitation has been seldom reported, which is partly ascribable to the lack of suitable materials. In this study, a small-molecule-based αvβ3-targeted NIR-II photoacoustic/NIR-IIa fluorescent probe IR-32p was generated and subsequently evaluated in U87MG tumor-bearing mice excited with NIR-I and NIR-II light. Exceptional dual-modal imaging properties such as good tumor uptake, high targeting specificity, and high tumor contrast were achieved in an orthotopic glioma model under 1020/1064 nm excitation, exhibiting a superior imaging depth of glioma through the skull. Our study introduces an outstanding dual-modal contrast agent with NIR-II absorption and confirms the superiority of NIR-II excitation over NIR-I in in vivo NIR-II/PA imaging.

Advances of nanomedicine in treatment of atherosclerosis and thrombosis

Atherosclerosis (AS) is a chronic inflammatory vascular disease. Myocardial ischemia originated from AS is the main cause of cardiovascular diseases, one of the major factors contributing to the global disease burden. AS is typically quiescent until occurrence of plaque rupture and thrombosis, leading to acute coronary syndrome and sudden death. Currently, clinical diagnostic techniques suffer from major pitfalls including lack of accuracy and specificity, which makes it rather difficult for drugs to directly target plaques to achieve therapeutic effect. Therefore, how to accurately diagnose and effectively intervene vulnerable AS plaques to achieve accurate delivery of drugs has become an urgent and evolving clinical problem. With the rapid development of nanomedicine and nanomaterials, nanotechnology has shown unique advantages in monitoring vulnerable plaques and thrombus and improving drug efficacy. Recent studies have shown that application of nanoparticle drug delivery system can booster the safety and effectiveness of drug therapy, and molecular imaging technology and nanomedicine also exhibit high clinical application potentials in disease diagnosis. Therefore, nanotechnology provides another promising avenue for diagnosis and treatment of AS and thrombosis, and has shown excellent performance in the development of targeted drug therapy and biomaterials. In this review, the research progress, challenges and prospects of nanotechnology in AS and thrombosis are discussed, expecting to provide new ideas for the prevention, diagnosis and treatment of AS and thrombosis.

Near-infrared-II photoacoustic imaging and photo-triggered synergistic treatment of thrombosis via fibrin-specific homopolymer nanoparticles

The formation of an occlusive thrombus in the blood vessel is the main culprit for numerous life-threatening cardiovascular diseases that represent the leading cause of morbidity and mortality worldwide. Herein, we develop a polymer nanoplatform that integrates long-wavelength second near-infrared (NIR-II) photoacoustic imaging-based thrombosis detection and antithrombotic activity. We design and synthesize a semiconducting homopolymer with strong absorption in the NIR-II region and molecular motion that boosts photothermal conversion and photoacoustic signal. We dope the homopolymer with a thermosensitive nitric oxide donor to formulate a nanoplatform, on which a fibrin-specific ligand is functionalized to ensure selective thrombus targeting. We show that with strong NIR-II light harvesting capability, bright photoacoustic signal and active thrombus accumulation ability, the NIR-II photoacoustic nanoprobes are able to sensitively and selectively delineate thrombi. We find that the nanoplatform also displays rapid and efficient blood clot removal activity with nearly complete blood flow restoration in both carotid thrombosis models and low extremity arterial thrombosis models under NIR-II light trigger by integrating a thrombus-localized photothermal effect and on-demand nitric oxide release. This nanoplatform offers a versatile approach for the diagnosis and treatment of life-threatening diseases caused by various thrombotic disorders.

New Perylene-Based Chemiluminescent Polymer Nanoparticles for Highly Selective Detection of the Superoxide Anion In Vivo

The superoxide anion (O2•-) is one of the primary reactive oxygen species in biological systems. Developing a determination system for O2•- in vivo has attracted much attention thanks to its complex biological function. Herein, we proposed a new perylene-based chemiluminescence (CL) probe, the SH-PDI polymer, which was capable of generating strong CL signals with O2•- in comparison with other ROS. The CL mechanism involved was proposed to be a kind of oxidation reaction induced by the breakage of the S-S and S-H bonds into sulfoxide bonds by O2•-. Subsequently, a nanoprecipitation method was introduced, using cumene-terminated poly(styrene-co-maleic anhydride) as the amphiphilic agent, to obtain water-soluble nanoparticles, SPPS NPs, which exhibited not only stronger CL intensity but also higher selectivity toward O2•- than the SH-PDI polymer. Moreover, the CL wavelength of the SPPS-O2•- system was found to be located at 580 and 710 nm, which was conducive to CL imaging. By virtue of these advantages, SPPS NPs were utilized to evaluate the O2•- level in vitro in the range of 0.25-60 μM at pH 7.0, with a detection limit of 8.2 × 10-8 M (S/N = 3). Moreover, SPPS NPs were also capable of imaging O2•- in an LPS-induced acute inflammation mice model and drug-induced acute kidney injury (AKI).

Recent theranostic applications of hydrogen peroxide-responsive nanomaterials for multiple diseases

It is well established that hydrogen peroxide (H2O2) is associated with the initiation and progression of many diseases. With the rapid development of nanotechnology, the diagnosis and treatment of those diseases could be realized through a variety of H2O2-responsive nanomaterials. In order to broaden the application prospects of H2O2-responsive nanomaterials and promote their development, understanding and summarizing the design and application fields of such materials has attracted much attention. This review provides a comprehensive summary of the types of H2O2-responsive nanomaterials including organic, inorganic and organic-inorganic hybrids in recent years, and focused on their specific design and applications. Based on the type of disease, such as tumors, bacteria, dental diseases, inflammation, cardiovascular diseases, bone injury and so on, key examples for above disease imaging diagnosis and therapy strategies are introduced. In addition, current challenges and the outlook of H2O2-responsive nanomaterials are also discussed. This review aims to stimulate the potential of H2O2-responsive nanomaterials and provide new application ideas for various functional nanomaterials related to H2O2.

A targeted activatable NIR-II nanoprobe for positive visualization of anastomotic thrombosis and sensitive identification of fresh fibrinolytic thrombus

Anastomotic thrombosis prevalently causes anastomosis failure, accompanied with ischemia and necrosis, the early diagnosis of which is restricted by inherent shortcomings of traditional imaging techniques in clinic and lack of appropriate prodromal biomarkers for thrombosis initiation. Herein, a fresh thrombus-specific molecular event, protein disulfide isomerase (PDI) is innovatively chosen as the activating factor, and a thrombosis targeting and PDI-responsive turn-on near infrared II (NIR-II) fluorescence nanoprobe is firstly developed. The supramolecular complex-based nanoprobe IR806-PDA@BSA-CREKA is fabricated by assembling NIR-II emitting cyanine derivative IR806-PDA with bovine serum albumin (BSA), which could ameliorate the stability and pharmacokinetics of the nanoprobe, addressing the contradiction in the balance of brightness and biocompatibility. The NIR-II-off nanoprobe exhibits robust turn-on NIR-II fluorescence upon PDI-specific activation, in vitro and in vivo. Of note, the constructed nanoprobe demonstrates superior photophysical stability, efficient fibrin targeting peptide-derived thrombosis binding and a maximum signal-to-background ratio (SBR) of 9.30 for anastomotic thrombosis in NIR-II fluorescent imaging. In conclusion, the exploited strategy enables positive visualized diagnosis for anastomotic thrombosis and dynamic monitoring for thrombolysis of fresh fibrinolytic thrombus, potentially contributes a novel strategy for guiding the therapeutic selection between thrombolysis and thrombectomy for thrombosis treatment in clinic.

Perylenediimides with Enhanced Autophagy Inhibition for a Dual-Light Activatable Photothermal Gas Therapy

Photothermal therapy (PTT) has emerged as a promising strategy for the treatment of tumors. However, the intrinsic self-repair mechanism of cells and the nonspecific photothermal effect of photothermal agents can result in poor treatment outcomes and normal tissue injury. To address this issue, we developed a dual light activatable perylenediimide derivative (P-NO) for nitric oxide-enhanced PTT. P-NO can self-assemble into nanoparticles in aqueous solutions. The P-NO nanoparticles are capable of releasing both NO and a photothermal molecule (P-NH) upon green light irradiation. The simultaneous release of NO and P-NH activates the photothermal effect and inhibits cell protection autophagy, thereby improving the therapeutic efficacy of PTT under near-infrared (NIR) light. Moreover, the switch on of NIR fluorescence allows real-time monitoring of the release of P-NH. Remarkably, in a mouse subcutaneous tumor model, significant tumor ablation can be achieved following dual light activated photothermal gas therapy. This work offers a promising and straightforward approach to constructing activatable perylenediimide-based photothermal agents for enhancing the effectiveness of photothermal gas therapy.

EGFR-targeted semiconducting polymer nanoparticles for photoacoustic imaging

Semiconducting polymer nanoparticles (SPN), formulated from organic semiconducting polymers and lipids, show promise as exogenous contrast agents for photoacoustic imaging (PAI). To fully realise the potential of this class of nanoparticles for imaging and therapeutic applications, a broad range of active targeting strategies, where ligands specific to receptors on the target cells are displayed on the SPN surface, are urgently needed. In addition, effective strategies for quantifying the level of surface modification are also needed to support development of ligand-targeted SPN. In this paper, we have developed methods to prepare SPN bearing peptides targeted to Epidermal Growth Factor Receptors (EGFR), which are overexpressed at the surface of a wide variety of cancer cell types. In addition to fully characterising these targeted nanoparticles by standard methods (UV-visible, photoacoustic absorption, dynamic light scattering, zeta potential and SEM), we have developed a powerful new NMR method to determine the degree of conjugation and the number of targeting peptides attached to the SPN. Preliminary in vitro experiments with the colorectal cancer cell line LIM1215 indicated that the EGFR-targeting peptide conjugated SPN were either ineffective in delivering the SPN to the cells, or that the targeting peptide itself destabilised the formulation. This in reinforces the need for effective characterisation techniques to measure the surface accessibility of targeting ligands attached to nanoparticles.

Recent Advances in Applications of Fluorescent Perylenediimide and Perylenemonoimide Dyes in Bioimaging, Photothermal and Photodynamic Therapy

The emblematic perylenediimide (PDI) motif which was initially used as a simple dye has undergone incredible development in recent decades. The increasing power of synthetic organic chemistry has allowed it to decorate PDIs to achieve highly functional dyes. As these PDI derivatives combine thermal, chemical and photostability, with an additional high absorption coefficient and near-unity fluorescence quantum yield, they have been widely studied for applications in materials science, particularly in photovoltaics. Although PDIs have always been in the spotlight, their asymmetric counterparts, perylenemonoimide (PMI) analogues, are now experiencing a resurgence of interest with new efforts to create architectures with equally exciting properties. Namely, their exceptional fluorescence properties have recently been used to develop novel systems for applications in bioimaging, biosensing and photodynamic therapy. This review covers the state of the art in the synthesis, photophysical characterizations and recently reported applications demonstrating the versatility of these two sister PDI and PMI compounds. The objective is to show that after well-known applications in materials science, the emerging trends in the use of PDI- and PMI-based derivatives concern very specific biomedicinal applications including drug delivery, diagnostics and theranostics.

2D MXene-Based Biosensing: A Review

MXene emerged as decent 2D material and has been exploited for numerous applications in the last decade. The remunerations of the ideal metallic conductivity, optical absorbance, mechanical stability, higher heterogeneous electron transfer rate, and good redox capability have made MXene a potential candidate for biosensing applications. The hydrophilic nature, biocompatibility, antifouling, and anti-toxicity properties have opened avenues for MXene to perform in vitro and in vivo analysis. In this review, the concept, operating principle, detailed mechanism, and characteristic properties are comprehensively assessed and compiled along with breakthroughs in MXene fabrication and conjugation strategies for the development of unique electrochemical and optical biosensors. Further, the current challenges are summarized and suggested future aspects. This review article is believed to shed some light on the development of MXene for biosensing and will open new opportunities for the future advanced translational application of MXene bioassays.

Chloroplast-boosted photodynamic therapy for effective drug-resistant bacteria killing and biofilm ablation

Due to the misuse of various antibiotics, the problem of bacterial resistance has become more serious worldwide, and the associated diseases have significantly increased the medical burden of society. Antimicrobial photodynamic therapy (PDT) has received widespread attention because of its safety, efficiency, and facile implementation. Here, we report an oxygen-supply antibacterial agent (Ce6@CS/CP), which could enhance the efficacy of antibacterial PDT via photosynthesis of O₂. Ce6@CS/CP displayed a robust interaction with bacteria, hence facilitating the delivery efficiency of Ce6. In vitro experiments demonstrated that the photodynamic bactericidal potency of Ce6@CS/CP was remarkably greater than that of free Ce6. Furthermore, Ce6@CS/CP also exhibited superior significant antibiofilm activity to free Ce6. As a live oxygen-supply antibacterial agent, Ce6@CS/CP possesses excellent bacteria delivery ability of Ce6 and could enhance the potency of antibacterial PDT by photosynthesis, offering a new strategy for fighting against drug-resistant bacteria.

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.

Cyclic RGD functionalized PLGA nanoparticles loaded with noncovalent complex of indocyanine green with urokinase for synergistic thrombolysis

Thrombotic diseases have the characteristics of long latency period, rapid onset, and high mortality rate, which seriously threaten people’s life and health. The aim of this research is to fabricate a novel indocyanine green complex of urokinase (ICG@uPA) and employ the amphiphilic PEG-PLGA polymer to deliver the complex as an enzyme-phototherapeutic synergistic thrombolysis platform. The noncovalent indocyanine green (ICG) complex of urokinase (ICG@uPA) was prepared via supramolecular self-assembly and then encapsulated into cRGD decorated polymeric nanoparticles (cRGD-ICG-uPA NPs) by double-emulsion solvent evaporation method. Then the nanoparticles (NPs) were characterized in terms of particle size, optical properties, in vitro release, etc. The targeting and thrombolytic effect of the nanoparticles were studied both in vitro and in vivo. ICG@uPA and cRGD-ICG-uPA NPs displayed significantly higher photostability and laser energy conversion efficiency than free ICG. Concomitantly, the NPs exhibited selective binding affinity to the activated platelets and specific accumulation in the mouse mesenteric vessel thrombus. Significant thrombolysis was achieved in vivo by photo-assisted synergistic therapy with reduced dose and systemic bleeding risk of uPA. Our results prove that the functional PLGA nanoparticle loaded with the ICG@uPA offers a novel option for effective and safe thrombolytic treatment.

Contrast Agents for Photoacoustic Imaging: A Review Focusing on the Wavelength Range

Photoacoustic imaging using endogenous chromophores as a contrast has been widely applied in biomedical studies owing to its functional imaging capability at the molecular level. Various exogenous contrast agents have also been investigated for use in contrast-enhanced imaging and functional analyses. This review focuses on contrast agents, particularly in the wavelength range, for use in photoacoustic imaging. The basic principles of photoacoustic imaging regarding light absorption and acoustic release are introduced, and the optical characteristics of tissues are summarized according to the wavelength region. Various types of contrast agents, including organic dyes, semiconducting polymeric nanoparticles, gold nanoparticles, and other inorganic nanoparticles, are explored in terms of their light absorption range in the near-infrared region. An overview of the contrast-enhancing capacity and other functional characteristics of each agent is provided to help researchers gain insights into the development of contrast agents in photoacoustic imaging.

Brain Accumulation and Toxicity Profiles of Silica Nanoparticles: The Influence of Size and Exposure Route

Nanoparticles (NPs) can make their way to the brain and cause in situ damage, which is a concern for nanomaterial application and airborne particulate matter exposure. Our recent study indicated that respiratory exposure to silica nanoparticles (SiO₂ NPs) caused unexpected cardiovascular toxic effects. However, the toxicities of SiO₂ NPs in other organs have warranted further investigation. To confirm the accumulation of SiO₂ NPs in the brain, we introduced SiO₂ NPs with different diameters into mice via intranasal instillation (INI) and intravenous injection (IVI) in parallel. We found that SiO₂ NPs may target the brain through both olfactory and systemic routes, but the size of SiO₂ NPs and delivery routes both significantly affected their brain accumulation. Surprisingly, while equivalent SiO₂ NPs were found in the brain regions, brain lesions were distinctly much higher in INI than in the IVI group. Mechanistically, we showed that SiO₂ NPs introduced via INI induced brain apoptosis and autophagy, while the SiO₂ NPs introduced via IVI only induced autophagy in the brain.

Advances of nano drug delivery system for the theranostics of ischemic stroke

From the global perspective, stroke refers to a highly common cause of disability and death. Ischemic stroke (IS), attributed to blood vessel blockage, preventing the flow of blood to brain, acts as the most common form of stroke. Thus far, thrombolytic therapy is the only clinical treatment for IS with the approval from the FDA. Moreover, the physiology barrier complicates therapeutically and diagnostically related intervention development of IS. Accordingly, developing efficient and powerful curative approaches for IS diagnosis and treatment is urgently required. The advent of nanotechnology has brought dawn and hope to better curative and imaging forms for the management of IS. This work reviews the recent advances and challenges correlated with the nano drug delivery system for IS therapy and diagnosis. The overview of the current knowledge of the important molecular pathological mechanisms in cerebral ischemia and how the drugs cross the blood brain barrier will also be briefly summarized.

Nonaromatic Organonickel(II) Phototheranostics

Earth-abundant metal-based theranostics, agents that integrate diagnostic and therapeutic functions within the same molecule, may hold the key to the development of low-cost personalized medicines. Here, we report a set of O-linked nonaromatic benzitripyrrin (C^N^N^N) macrocyclic organonickel(II) complexes, Ni-1-4, containing strong σ-donating M-C bonds. Complexes Ni-1-4 are characterized by a square-planar coordination geometry as inferred from the structural studies of Ni-1. They integrate photothermal therapy, photothermal imaging, and photoacoustic imaging (PAI) within one system. This makes them attractive as potential phototheranostics. Relative to traditional Ni(II) porphyrins, such as F₂₀TPP (tetrapentafluorophenylporphyrin), the lowest energy absorption of Ni-1 is shifted into the near infrared region, presumably as a consequence of Ni-C bonding. Ultrafast transient absorption spectroscopy combined with theoretical calculations revealed that, upon photoexcitation, a higher population of ligand-centered and ³MLCT states is seen in Ni-1 relative to NiTPBP (TPBP = 6,11,16,21-tetraphenylbenziporphyrin). Encapsulating Ni-1 in 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG₂₀₀₀) afforded nanoparticles, Ni-1@DSPE, displaying red-shifted absorption features, as well as good photothermal conversion efficiency (∼45%) in aqueous media. Proof-of-principle experiments involving thrombus treatment were carried out both in vitro and in vivo. It was found that Ni-1@DSPE in combination with 785 nm photo-irradiation for 3 min (0.3 W/cm²) proved successful in removing blood clots from a mouse thrombus model as monitored by photoacoustic imaging (PAI). The present work highlights the promise of organonickel(II) complexes as potential theranostics and the benefits that can accrue from manipulating the excited-state features of early transition-metal complexes via, for example, interrupting π-conjugation pathways.

A Fibrin Site-Specific Nanoprobe for Imaging Fibrin-Rich Thrombi and Preventing Thrombus Formation in Venous Vessels

Venous thromboembolism (VTE) is a prevalent public health issue worldwide. Before treatment, spatiotemporally accurate thrombus detection is essential. However, with the currently available imaging technologies, this is challenging. Herein, the development of a novel fibrin-specific nanoprobe (NP) based on the conjugation of poly(lactic-co-glycolic acid) with the pentapeptide Cys-Arg-Glu-Lys-Ala (CREKA) for selective and semiquantitative imaging in vivo is presented. By integrating Fe₃ O₄ and NIR fluorochrome (IR780), the NP can function as a highly sensitive sensor for the direct analysis of thrombi in vivo. The fibrin-specific NP distinguishes fibrin-rich thrombi from collagen-rich or erythrocyte-rich thrombi, which can be beneficial for future individually tailored therapeutic strategy. Furthermore, loading NPs with the ketotifen fumarate results in mast cell degranulation inhibition, and hence, NPs can prevent thrombosis without the risk of excessive bleeding. Thus, the use of fibrin-specific NPs may serve as a safe alternative approach for the detection and prevention of VTEs in susceptible populations in the future.

Cyclo(RGD) peptide-decorated silver nanoparticles with anti-platelet potential for active platelet-rich thrombus targeting

The development of integrated nanomedicine for prevention and early diagnosis of thrombosis is highly significant. Platelet plays a vital role in thrombotic disorders, offering an ideal target for thromboprophylaxis and imaging of thrombi. We herein fabricated cyclo(RGD) peptide-decorated AgNPs (designated cRGD-AgNPs) for active targeting platelet-rich thrombi. In vitro cytotoxicity and hemolysis assays demonstrated that cRGD-AgNPs have acceptable biocompatibility pattern. Both PEG-AgNPs (non-targeted version) and cRGD-AgNPs can inhibit agonist-mediated platelet aggregation, whereas the latter exhibited significant attenuation on platelet activation and adhesion onto collagen and fibrinogen matrix. Furthermore, the superior binding ability of cRGD-AgNPs with platelet-rich thrombus was demonstrated in static/dynamic condition in vitro. In vivo studies revealed that cRGD-AgNPs could actively target thrombi in a mouse model of carotid artery thrombi with favorable safety. Our results here suggest that cRGD-AgNPs with intrinsic anti-platelet potential might be promising nano theranostics for thromboprophylaxis and active thrombus targeting.

Nanocarrier-Based Management of Venous and Arterial Thrombosis

Cardiovascular diseases represent the leading cause of mortality worldwide, with recent epidemiological studies revealing an increasing trend of prevalence and incidence globally. Among cardiovascular disorders, both arterial and venous thrombosis and particularly their acute life-threating complications such as ischemic stroke, acute myocardial infarction, deep venous thrombosis and pulmonary embolism are responsible for more than 25% of all deaths worldwide. The modern approach following progresses in anticoagulant, thrombolytic and antiaggregant therapies has significantly improved the prognoses of these conditions in the last past decades. However, several challenges still remain such as achieving the optimal drug concentration at the injured site, reducing the shortcomings of drug resistance and the incidence of life-threatening hemorrhages. Nanomedicine is a well-known field of medicine in which atomic and molecular structures ranging between 0.1–100 nm are used in various domains due to their specific mechanical, electrical, thermal and magnetic properties. Recent experimental and clinical evidence have shown that nanotechnology could be a safe, effective and an appealing approach for various non-cardiovascular and cardiovascular diseases such as thromboembolic conditions. In this review, we have described the most promising nanotechnology-based approaches not only for the diagnosis, but also for the treatment of vascular thrombotic diseases.

Semiconducting Polymer Nanoparticles for Photoactivatable Cancer Immunotherapy and Imaging of Immunoactivation

Immunotherapy that stimulates the body's own immune system to kill cancer cells has emerged as a promising cancer therapeutic method. However, some types of cancer exhibited a low response rate to immunotherapy, and the high risk of immune-related side effects has been aroused during immunotherapy, which greatly restrict its broad applications in cancer therapy. Phototherapy that uses external light to trigger the therapeutic process holds advantages including high selectivity and efficiency, and low side effects. Recently, it has been proven to be able to stimulate immune response in the tumor region by inducing immunogenic cell death (ICD), the process of which was termed photo-immunotherapy, dramatically improving therapeutic specificity over conventional immunotherapy in several aspects. Among numerous optical materials for photo-immunotherapy, semiconducting polymer nanoparticles (SPNs) have gained more and more attention owing to their excellent optical properties and good biocompatibility. In this review, we summarize recent developments of SPNs for immunotherapy and imaging of immunoactivation. Different therapeutic modalities triggered by SPNs including photo-immunotherapy and photo-immunometabolic therapy are first introduced. Then, applications of SPNs for real-time monitoring immunoactivation are discussed. Finally, the conclusion and future perspectives of this research field are given.

Acoustics at the nanoscale (nanoacoustics): A comprehensive literature review.: Part II: Nanoacoustics for biomedical imaging and therapy

In the past decade, acoustics at the nanoscale (i.e., nanoacoustics) has evolved rapidly with continuous and substantial expansion of capabilities and refinement of techniques. Motivated by research innovations in the last decade, for the first time, recent advancements of acoustics-associated nanomaterials/nanostructures and nanodevices for different applications are outlined in this comprehensive review, which is written in two parts. As part II of this two-part review, this paper concentrates on nanoacoustics in biomedical imaging and therapy applications, including molecular ultrasound imaging, photoacoustic imaging, ultrasound-mediated drug delivery and therapy, and photoacoustic drug delivery and therapy. Firstly, the recent developments of nanosized ultrasound and photoacoustic contrast agents as well as their various imaging applications are examined. Secondly, different types of nanomaterials/nanostructures as nanocarriers for ultrasound and photoacoustic therapies are discussed. Finally, a discussion of challenges and future research directions are provided for nanoacoustics in medical imaging and therapy.

Thrombus-Targeting Polymeric Nanocarriers and Their Biomedical Applications in Thrombolytic Therapy

Due to the high morbidity and mortality of cardiovascular diseases, there is an urgent need for research on antithrombotic strategies. In view of the short half-life, insufficient drug penetration, poor targeting capabilities, and hemorrhagic side-effects of traditional thrombus treatment methods, the combination of thrombolytic therapy and nanocarriers brought by the development of nanotechnology in recent years may provide effective solutions for these undesirable side-effects caused by insufficient targeting. Polymeric nanocarriers, based on macromolecules and various functional groups, can connect specific targeting molecules together through chemical modification to achieve the protection and targeted delivery of thrombolytic drugs. However, simple chemical molecular modifications may be easily affected by the physiological environment encountered in the circulatory system. Therefore, the modification of nanocarriers with cell membranes can provide camouflage to these platforms and help to extend their circulation time while also imparting them with the biological functions of cell membranes, thus providing them with precise targeting capabilities, among which the most important is the biological modification of platelet membranes. In addition, some nanoparticles with their own therapeutic functions have also been developed, such as polypyrrole, which can exhibit a photothermal effect to induce thrombolysis. Herein, combined with the mechanism of thrombosis and thrombolysis, we outline the recent advances achieved with thrombus-targeting nanocarriers with regard to thrombosis treatment. On this basis, the design considerations, advantages, and challenges of these thrombolytic therapies in clinical transformation are discussed.

Perylene diimide-based treatment and diagnosis of diseases

Integrated treatment using imaging technology to monitor biological processes for the precise treatment and diagnosis of diseases to improve treatment outcomes is becoming a hot topic. Accordingly, perylene diimide (PDI) has excellent photothermal conversion and photostability, which can be used as a good material for disease treatment and diagnosis. Herein, we review the latest research progress on the real-time diagnosis of related diseases based on perylene diimide probes in the aspects of bioimaging, detection of biomarkers and determination of the pH in living cells. Furthermore, perylene diimide-based multifunctional nano-delivery systems are particularly emphasized, showing great therapeutic potential in the field of image-guided combination therapy in tumor therapy. Finally, the great opportunities and challenges still faced by perylene diimide before entering the clinic are comprehensively analyzed.

Activated Platelet-Homing Nanoplatform for Targeting Magnetic Resonance Imaging of Aneurysm-Related Thrombus in Rabbits

Thrombosis is closely related to the instability of intracranial aneurysm (IA), whose rupture is associated with high morbidity and mortality. It is difficult to detect an IA-related thrombus because traditional magnetic resonance imaging (MRI) and even contrast-enhanced MRI cannot clearly distinguish a thrombus from the surrounding tissues. Herein, a nanoplatform [(MFe₂O₄-ZnDPA nanoparticles (NPs)], consisting of Zn_0.4Co_0.6Fe₂O₄@Zn_0.4Mn_0.6Fe₂O₄ NPs for imaging and Zn(II)-bis(dipicolylamine) (ZnDPA) for thrombus targeting, is constructed to target an experimental aneurysm-related thrombus in rabbits via MRI. In vitro experiments including platelet safety evaluation primarily prove that MFe₂O₄-ZnDPA NPs with a high MRI transverse relaxation time (T₂) have good biocompatibility. MFe₂O₄-ZnDPA NPs could target a thrombus via the special interaction between ZnDPA and phosphatidylserine of activated platelets in the thrombus through MRI and Fe quantification assays. Moreover, after MFe₂O₄-ZnDPA NPs are injected into the ear vein of common carotid artery aneurysm model rabbits, MRI shows that MFe₂O₄-ZnDPA NPs could accumulate in the aneurysm-related thrombus from 0 to 15 min after injection and decrease in the next 45 min. Meanwhile, MFe₂O₄-ZnDPA NPs could decrease the MRI T₂ signal of the aneurysm-related thrombus to enhance the outline of the aneurysm. This study demonstrates that a nanoplatform can enhance the detection of an aneurysm-related thrombus as well as aneurysm itself to assist further treatment of IA.

Aggregation-Induced Emission and Temperature-Dependent Luminescence of Potassium Perylenetetracarboxylate

Investigation of temperature-dependent photoluminescent properties of potassium perylene-3,4,9,10-tetracarboxylate (K₄PTC), a molecule with no internal rotational degrees of freedom, shows aggregation-induced enhanced emission at room temperature. The different excitonic emission processes are dependent of temperature, some of which quenches in an intermediate temperature range (from 50 to 150 K). The exciton excited states switching phenomenon from "dark" to "bright" states is observed and its explained using Herzberg-Teller selection rule. K₄PTC is a molecule comparable to the size of its precursor, perylene-3,4,9,10-tetracarboxylic anhydride (PTCDA) and is highly soluble in water, contrary to PTCDA, which is poorly soluble in most solvents. Powder x-ray diffraction measurements corroborate a lesser degree of ordering of bulk K₄PTC compared to bulk PTCDA. The green luminescent molecule could, in principle, be used as a biomarker, or in photodynamic therapy, if further studies show relatively low toxicity.

Targeted Thrombolytic Therapy with Metal-Organic-Framework-Derived Carbon Based Platforms with Multimodal Capabilities

A dual-response (near-infrared, alternating magnetic field) multifunctional nanoplatform was developed based on urokinase plasminogen activators (uPA)-loaded metal-organic-framework (MOF)-derived carbon nanomaterials (referred to uPA@CFs below) for thrombolytic therapy. uPA loaded in mesoporous CFs could be released under the action of near-infrared (NIR)-mediated photothermy to achieve superficial thrombolysis. More importantly, with the assistance of alternating magnetic field (AMF), this system could also precisely heat the thrombosis in the deep tissue area. Quantitative experiments proved that the thrombolytic efficiency of this dual-response system at deep venous thrombosis was nearly 6 times than that of NIR alone. This is the first application that MOF-derived carbon nanomaterials in the field of targeted thrombolysis. To our delight, the MOF-derived carbon nanomaterials (CFs) not only maintained the drug-carrying capacity, but also endowed CFs with reliable magnetic targeting ability. More encouragingly, the CFs also showed extraordinary angiogenic performance, thus opening up the prospect of its clinical application.

Regioisomer-manipulating thio-perylenediimide nanoagents for photothermal/photodynamic theranostics

Thionated perylenediimides (PDIs) can potentially generate thermal and reactive oxygen species and thus can be used as theranostic agents for photothermal/photodynamic therapy. Herein, thionated cis-/trans-isomer PDI-CS and PDI-TS were designed and prepared to investigate thionation engineering on therapeutic performance. The results revealed that the photodynamic performance is less associated with the positon of sulfur atoms. By contrast, trans-isomer PDI-TS showed a photothermal conversion efficiency of up to 58.4%, which was 40% higher than that of PDI-CS (∼41.6%). An in vitro half-maximal inhibitory concentration of ∼7.78 μg mL-1 was achieved for PDI-TS, which was 1.7-fold smaller than that of PDI-CS, strongly reasserting the regioisomer-modulated phototheranostic performance. Notably, the strong π-π and CS interactions in PDI-TS nanoagents are essential factors attributed to their excellent photothermal performance, indicating that the optimization of non-bonding interactions is an ingenious way to improve phototheranostic performance. This work provides a facile means of creating thio-perylenediimides that possess excellent antitumor properties and a novel proof of concept to improve therapeutic performance through the optimization of non-bonding interactions.

Targeted nanotherapeutics in the prophylaxis and treatment of thrombosis

Currently available anti-thrombotic therapy for the prophylaxis and treatment of arterial and venous thrombosis includes intravenous administration of anti-thrombotic drugs which lead to severe bleeding risks such as cerebral hemorrhage and stroke. Targeting approaches that utilize nanosystems to reach the thrombus sites are emerging to increase the local effect of anti-thrombotic drugs, as well as to decrease these severe bleeding complications by diminishing the systemic availability of these drugs. This review emphasizes the emerging targeted nanomedicines (liposomes, micelles, polymeric nanoparticles, material bases nanoparticles and other biological vectors) for the prophylaxis and treatment of thrombotic events as well as multifunctional nanomedicines for theranostic applications. Nanomedicine offers a promising platform for a smart, safe, and effective approach for the management of thrombosis.

Photoacoustic imaging as a highly efficient and precise imaging strategy for the evaluation of brain diseases

Photoacoustic imaging (PAI) is an emerging imaging strategy with a unique combination of rich optical contrasts, high ultrasound spatial resolution, and deep penetration depth without ionizing radiation. Taking advantage of the features mentioned above, PAI has been widely applied to preclinical studies in diverse fields, such as vascular biology, cardiology, neurology, ophthalmology, dermatology, gastroenterology, and oncology. Among various biomedical applications, photoacoustic brain imaging has great importance due to the brain's complex anatomy and the variability of brain disease. In this review, we aimed to introduce a novel and effective imaging modality for diagnosing brain diseases. Firstly, a brief overview of two major types of PAI system was provided. Then, PAI's major preclinical applications in brain diseases were introduced, including early diagnosis of brain tumors, subtle changes in the chemotherapy response, epileptic activity and brain injury, foreign body, and brain plaque. Finally, a perspective of the remaining challenges of PAI was given for future advancements.

In vivo Multi-scale Photoacoustic Imaging Guided Photothermal Therapy of Cervical Cancer based on Customized Laser System and Targeted Nanoparticles

BACKGROUND

Effective treatment strategy for cervical carcinoma is subject to the limitation of its anatomical location and histological characteristics. Comprehensive imaging before cervical carcinoma treatment is of great significance for the patients. Current imaging methods cannot meet the requirements of high resolution, deep imaging depth and non-invasive imaging at the same time. Fortunately, Photoacoustic imaging (PAI) is a novel imaging method that combines rich optical contrast, high ultrasonic spatial resolution, and deep penetration depth in a single modality. Moreover, PAI-guided photothermal therapy (PTT) by aid of targeting nanoparticles is an emerging and effective cancer treatment in recent years.

METHODS

Here, strong near-infrared region (NIR) absorption-conjugated polymer PIIGDTS (PD) nanoparticles with folic acid (FA) modification (namely, PD-FA) that targeted at Hela cell were specifically designed as cervical tumor imaging contrast agents and photothermal agents.

RESULTS

The obtained PD-FA nanoparticles exhibited admirable photoacoustic contrast-enhancing ability and desirable PTT behavior with the photothermal conversion efficiency as high as 62.6% in vitro. Furthermore, the PAI performance and PTT efficiency were tested in HeLa tumor-bearing nude mice after injection of PD-FA nanoparticles. In vivo multi-scale, PAI provided B-san and 3D dimension imaging for intuitive and comprehensive information of Hela tumor. Moreover, the Hela tumor can be completely eliminated within 18 days after PTT, with no toxicity and side effects.

CONCLUSION

In summary, PD-FA injection combined with PAI and PTT systems provides a novel powerful tool for early diagnosis and precise treatment of cervical cancer.

Molecular engineering of diketopyrrolopyrrole-conjugated polymer nanoparticles by chalcogenide variation for photoacoustic imaging guided photothermal therapy

Photothermal therapy is promising for augmenting cancer therapeutic outcomes in cancer treatment. Diketopyrrolopyrrole (DPP)-conjugated polymer nanoparticles are in focus due to their dual photoacoustic imaging and photothermal therapy functions. Herein, the design and synthesis of three near-infrared absorbing conjugated polymers, named DPP-SO, DPP-SS and DPP-SSe, with heteroatom substitution of the thiophene moiety were developed for a photoacoustic imaging guided photothermal therapy. It was demonstrated that systematically changing only the heteroatom from O to S or Se could apparently adjust the absorption spectrum and energy gap of DPP-conjugated polymers to obtain the most suitable photothermal transduction agents (PTAs) for use in biomedicine. The characterization of photophysical properties proved that the photothermal conversion efficiency and absorption coefficient of DPP-SO nanoparticles under 808 nm irradiation was up to 79.3% and 66.51 L g^-1 cm^-1, respectively, which were much higher than those of DPP-SS and DPP-SSe nanoparticles. Remarkably, the IC₅₀ value of DPP-SO for killing A549 cells was half that of DPP-SS and DPP-SSe nanoparticles. Further in vivo works demonstrated efficient photothermal therapeutic effects of DPP-SO nanoparticles with the guidance of photoacoustic imaging. Thus, this is an efficient method to regulate the photothermal performance of DPP-conjugated polymers by changing the heteroatom in the molecular skeleton.

Recent Developments on Semiconducting Polymer Nanoparticles as Smart Photo-Therapeutic Agents for Cancer Treatments-A Review

Semiconducting polymer nanoparticles (SPN) have been emerging as novel functional nano materials for phototherapy which includes PTT (photo-thermal therapy), PDT (photodynamic therapy), and their combination. Therefore, it is important to look into their recent developments and further explorations specifically in cancer treatment. Therefore, the present review describes novel semiconducting polymers at the nanoscale, along with their applications and limitations with a specific emphasis on future perspectives. Special focus is given on emerging and trending semiconducting polymeric nanoparticles in this review based on the research findings that have been published mostly within the last five years.

Synergistic non-bonding interactions based on diketopyrrolo-pyrrole for elevated photoacoustic imaging-guided photothermal therapy

Synergistic non-bonding interactions in fluorine and chalcogen-substituted diketopyrrolopyrrole nanoagents for elevated photoacoustic imaging-guided photothermal therapy.

Biomimetic fibrin-targeted and H2O2-responsive nanocarriers for thrombus therapy

Thrombosis is a principle cause of various life-threatening cardiovascular diseases. However, current antithrombotic treatments using drugs only offer limited efficacy due to short half-life, low targeting ability to the thrombus site, and unexpected bleeding complications. Taking into account of the biological characteristics of thrombus including upregulation of hydrogen peroxide (H₂O₂) and abundance of fibrin, we engineered a H₂O₂-responsive nanocarrier for thrombus-targeting delivery of an antithrombotic agent (i.e., tirofiban). The nanocarrier was composed of a drug-conjugated dextran nanocore and a red blood cell (RBC) membrane shell, and its surface was functionalized with a fibrin-targeting peptide, CREKA. Tirofiban was conjugated to dextran through a H₂O₂-cleavable phenylboronic ester linkage. The fibrin-targeting RBC membrane-cloaked dextran-tirofiban conjugate nanoparticles (i.e., T-RBC-DTC NPs) can scavenge H₂O₂ and provide controlled release of tirofiban to achieve site-specific antithrombotic effects. In RAW 264.7 cells and HUVECs, the T-RBC-DTC NPs effectively scavenged H₂O₂ and protected cells from H₂O₂-induced cytotoxicity. In the ferric chloride-induced carotid thrombosis mouse model, the T-RBC-DTC NPs efficiently accumulated at the injured carotid artery and exhibited significantly enhanced antithrombotic activity compared to free drug. The T-RBC-DTC NPs also exhibited good biocompatibility according to histology analysis. Overall, our results indicated that this bioengineered nanocarrier offers a promising therapeutic strategy for thrombotic disorders.

Human hair derived uPA loaded capsules with dual near-infrared (I and II biowindows) laser responsive capabilities for multi-effective thrombolysis therapy

Problems such as massive hemorrhage caused by uncontrolled drug dosage are the main significant obstacles in clinical thrombolytic therapy, which are prominently due to the lack of targeting and controlled release ability of efficient thrombolytic drug systems. In recent years, our team demonstrated that the photothermal effect can facilitate the thrombolytic effect of urokinase plasminogen activator (uPA). However, conventional photothermal agents are relatively expensive or contain heavy metals. If drug delivery systems with low toxicity, minimized heavy metal elements and easy accessibility (preferably provided by human self) can be developed, they will be of value in the future related applications. Herein, uPA-loaded human black hair derived nanoparticles with gelatin capsules (uPA@HBHNP@GNCs) were applied for the first time as a thrombolytic system. Upon irradiation by near-infrared I window (NIR-I) laser or II window (NIR-II) laser, the photothermal effect of HBHNP was triggered to promote the melting of the gelatin encapsulated around the outer layer, thereby realizing the targeted release of uPA. The in vitro and in vivo experiments demonstrated that the deep response to NIR (especially II window) of this system exhibited a satisfactory thrombolytic effect with ideal biosafety. Briefly, the proposed hair derived drug delivery system has the characteristics of human source, low cost, minimum heavy metal components, deep response to NIR (II window) laser, and good biocompatibility, which is expected to be expanded to the treatment for some diseases, even in deep tissue areas.

Functional gadolinium-based nanoscale systems for cancer theranostics

Cancer theranostics is a new strategy for combating cancer that integrates cancer imaging and treatment through theranostic agents to provide an efficient and safe way to improve cancer prognosis. Design and synthesis of these cancer theranostic agents are crucial since these agents are required to be biocompatible, tumor-specific, imaging distinguishable and therapeutically efficacious. In this regard, several types of gadolinium (Gd)-based nanomaterials have been introduced to combine different therapeutic agents with Gd to enhance the efficacy of therapeutic agents. At the same time, the entire treatment procedure could be monitored via imaging tools due to incorporation of Gd ions, Gd chelates and Gd/other imaging probes in the theranostic agents. This review aims to overview recent advances in the Gd-based nanomaterials for cancer theranostics and perspectives for Gd nanomaterial-based cancer theranostics are provided.

Thrombin-responsive engineered nanoexcavator with full-thickness infiltration capability for pharmaceutical-free deep venous thrombosis theranostics

Although nanotechnology has shown great promise for treating multiple vascular diseases in recent years, simultaneous noninvasive detection and efficient dissolution of deep venous thrombosis (DVT) still remains challenging. In particular, long blockage areas and large thrombus thicknesses in DVT cause enormous difficulties for site-specific deep-seated thrombus theranostics. Therefore, based on the unique components of DVT, the novel concept of a thrombin-responsive full-thickness infiltration nonpharmaceutical nanoplatform for DVT theranostics is proposed here. The penetration depth is innovatively enhanced with efficient targeting and accumulation in the whole thrombi. Herein, we report a thrombin-responsive phase-transition liposome incorporating a liquid perfluoropentane (PFP) core and modified with two binding peptides, activatable cell-penetrating peptide (ACPP) and fibrin-binding ligand (FTP), which contribute to efficient liposome targeting and accumulation within the thrombi. This targeted nanoplatform is constructed to dig out the thrombus with the assistance of low-intensity focused ultrasound (LIFU), performing the destructive function of an excavator via an acoustic droplet vaporization effect (acting as a "nanoexcavator" system), which can activate and vaporize into microbubbles to enhance LIFU efficacy. The resulting microbubbles enable real-time monitoring of the therapeutic process with ultrasound imaging and high performance photoacoustic imaging after loading DIR. This non-invasive nonpharmaceutical thrombolytic strategy is an improvement over existing clinical methods without systemic side effects.

An RGD modified water-soluble fluorophore probe for in vivo NIR-II imaging of thrombosis

Venous thrombosis leads to severe symptoms and death through pulmonary embolism. There is a great need for high sensitivity imaging methods to identify acute patients who would benefit from thrombolysis. We designed a novel, organic near-infrared second-window (NIR-II) probe, which targets the glycoprotein IIb/IIIa receptor (GPIIb/IIIa) on activated platelets. The probe's structure was characterized by MALDI-TOF-MS, TEM, UV-visible absorption and NIR-II fluorescent spectroscopy. The probe's specificity for activated platelets was investigated in vitro and in vivo. Thrombosis in mice was induced by administration of FeCl₃ in the external jugular vein and imaged by using a NIR-II imager. The donor-acceptor-donor fluorescent core TTQ was prepared from donor and acceptor units. TTQ-PEG-NH₂ was synthesized by sequential modification of PEGylated TTQ, followed by c(RGD) condensation. Signal strength was continuously monitored for 24 h following TTQ-PEG-c(RGD) or non-specific fluorescent dye injection. The contralateral external jugular vein, sham surgery and a competitive inhibition experiment served as controls. TTQ-PEG-c(RGD) presented high NIR-II intensity, good stability and excellent affinity for activated platelets. The NIR-II fluorescence signal of TTQ-PEG-c(RGD) injected mice significantly increased at the thrombus site and peaked at 4 h, whereas there was no significant change in the control mice, and the competitive inhibition of the RGD antagonist suppressed the enhancement of the NIR-II fluorescence signal. Comparison between fresh and old thrombi confirmed that TTQ-PEG-c(RGD) could be used to distinguish a fresh thrombus from an old thrombus. TTQ-PEG-c(RGD) can specifically target thrombosis in vitro and in vivo, providing a potential tool for noninvasive diagnosis of early thrombi.

Emerging nanotherapeutics for antithrombotic treatment

Thrombus causes insufficient blood flow and ischemia damages to brain and heart, leading to life-threatening cardio-cerebrovascular diseases. Development of efficient antithrombotic strategies has long been a high priority, owing to the high morbidity and mortality of thrombotic diseases. With the rapid development of biomedical nanotechnology in diagnosis and treatment of thrombotic disorder, remarkable progresses have been made in antithrombotic nanomedicines in recent years. Herein, we outline the recent advances in this field at the intersection of thrombus theranostics and biomedical nanotechnology. First, thrombus diagnosis techniques based on biomedical nanotechnology are presented. Then, emerging antithrombotic nanotherapeutics are overviewed, including thrombus-targeting strategies, thrombus stimuli-responsive nanosystems and phase transition-driven nanotherapeutics. Furthermore, multifunctional nanosystems for combination theranostics of thrombotic diseases are discussed. Finally, the design considerations, advantages and challenges of these biomedical nanotechnology-driven therapeutics in clinical translation are highlighted.

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.

Nano-Medicine for Thrombosis: A Precise Diagnosis and Treatment Strategy

Thrombosis is a global health issue and one of the leading factors of death. However, its diagnosis has been limited to the late stages, and its therapeutic window is too narrow to provide reasonable and effective treatment. In addition, clinical thrombolytics suffer from a short half-life, allergic reactions, inactivation, and unwanted tissue hemorrhage. Nano-medicines have gained extensive attention in diagnosis, drug delivery, and photo/sound/magnetic-theranostics due to their convertible properties. Furthermore, diagnosis and treatment of thrombosis using nano-medicines have also been widely studied. This review summarizes the recent advances in this area, which revealed six types of nanoparticle approaches: (1) in vitro diagnostic kits using "synthetic biomarkers"; (2) in vivo imaging using nano-contrast agents; (3) targeted drug delivery systems using artificial nanoparticles; (4) microenvironment responsive drug delivery systems; (5) drug delivery systems using biological nanostructures; and (6) treatments with external irradiation. The investigations of nano-medicines are believed to be of great significance, and some of the advanced drug delivery systems show potential applications in clinical theranotics.

EWVDV-Mediated Platelet-Targeting Nanoparticles for the Multimodal Imaging of Thrombi at Different Blood Flow Velocities

Background

There have been many recent reports of molecular probes for thrombi but with unsatisfactory in vivo targeting effects, which could be related to the blood flow velocity in vivo. Therefore, it is worth explaining the relationship between the targeting effect and the blood flow velocity.

Methods and Materials

In this study, we constructed a platelet-targeting nanoparticle (NP) based on EWVDV for targeting P-selectin combined with the phase transition material perfluorohexane and India ink to achieve the multimodal imaging of thrombi. We studied the targeting effect of the NPs for rabbit blood thrombi under different flow velocities simulating blood flow velocities in vivo.

Results

The results show the successful fabrication of NPs with the ability to undergo a phase transition via low-intensity focused ultrasound irradiation to achieve ultrasound imaging and with a high binding affinity for activated platelets. In vitro, low flow velocities (20 cm/s) hardly affected the targeting effect of the NPs, while moderate flow velocities (40 cm/s) reduced the number of NPs that target thrombi by 52.6% comparing to static fluid (0 cm/s). High flow velocities (60 cm/s) greatly reduced the targeting effect of the NPs by 83.5%.

Conclusion

These results can serve as a reference for the design of NPs targeting thrombi at different sites and in different blood vessel types according to the blood flow velocity, thereby establishing a foundation for in vivo experiments.