Different PEG-PLGA Matrices Influence In Vivo Optical/Photoacoustic Imaging Performance and Biodistribution of NIR-Emitting π-Conjugated Polymer Contrast Agents

Radioactive hybrid semiconducting polymer nanoparticles for imaging-guided tri-modal therapy of breast cancer

Due to the rapid progression and aggressive metastasis of breast cancer, its diagnosis and treatment remain a great challenge. The simultaneous inhibition of tumor growth and metastasis is necessary for breast cancer to obtain ideal therapeutic outcomes. We herein report the development of radioactive hybrid semiconducting polymer nanoparticles (SPNH) for imaging-guided tri-modal therapy of breast cancer. Two semiconducting polymers are used to form SPNH with a diameter of around 60 nm via nano-coprecipitation and they are also labeled with iodine-131 (131I) to enhance the imaging functions. The formed SPNH show good radiolabeling stability and excellent photodynamic and photothermal effects under 808 nm laser irradiation to produce singlet oxygen (1O2) and heat. Moreover, SPNH can generate 1O2 with ultrasound irradiation via their sonodynamic properties. After intravenous tail vein injection, SPNH can effectively accumulate in the subcutaneous 4T1 tumors of living mice as verified via fluorescence and single photon emission computed tomography (SPECT) imaging. With the irradiation of tumors using an 808 nm laser and US, SPNH mediate photodynamic therapy (PDT), photothermal therapy (PTT) and sonodynamic therapy (SDT) to kill tumor cells. Such a tri-modal therapy leads to an improved efficacy in inhibiting tumor growth and suppressing tumor metastasis compared to the sole SDT and combinational PDT-PTT. This study thus demonstrates the applications of SPNH to diagnose tumors and combine different therapies for effective breast cancer treatment.

Nanotechnology for brain tumor imaging and therapy based on π-conjugated materials: state-of-the-art advances and prospects

In contemporary biomedical research, the development of nanotechnology has brought forth numerous possibilities for brain tumor imaging and therapy. Among these, π-conjugated materials have garnered significant attention as a special class of nanomaterials in brain tumor-related studies. With their excellent optical and electronic properties, π-conjugated materials can be tailored in structure and nature to facilitate applications in multimodal imaging, nano-drug delivery, photothermal therapy, and other related fields. This review focuses on presenting the cutting-edge advances and application prospects of π-conjugated materials in brain tumor imaging and therapeutic nanotechnology.

RGD-directed 24 nm micellar docetaxel enables elevated tumor-liver ratio, deep tumor penetration and potent suppression of solid tumors

Nanomedicines while showing a great potential in improving the performance of chemotherapeutics like docetaxel (DTX) are distressed by a high liver deposition and poor tumor penetration, which might not only cause liver toxicity but also moderate therapeutic effect. Herein, we report that cRGD-directed 24 nm disulfide-crosslinked micellar docetaxel (cRGD-MDTX) presents low liver accumulation, high tumor uptake, and deep tumor penetration, leading to the potent suppression of different solid tumors. cRGD-MDTX was optimized with a cRGD density of 4% and DTX loading of 10 wt%. Interestingly, cRGD-MDTX enabled an extraordinary tumor-liver ratio of 2.8/1 with a DTX uptake of 8.3 %ID/g in αvβ3 over-expressing PC3 prostate tumor. The therapeutic studies demonstrated striking antitumor effects of cRGD-MDTX toward PC3 prostate tumor, prostate cancer patient-derived xenografts (PDX), orthotopic A549-Luc lung cancer and orthotopic SKOV3-Luc ovarian tumor models, in which tumor growth was effectually inhibited and 6-8 times better improvement of median survival time over free DTX was observed. This small disulfide-crosslinked micellar drug capable of relegating liver deposition opens a new avenue to nanomedicines for targeted therapy.

The Role of Stabilizing Copolymer in Determining the Physicochemical Properties of Conjugated Polymer Nanoparticles and Their Nanomedical Applications

Conjugated polymer nanoparticles (CPNs) are a promising class of nanomaterials for biomedical applications, such as bioimaging, gene and drug delivery/release, photodynamic therapy (PDT), photothermal therapy (PTT), and environmental sensing. Over the past decade, many reports have been published detailing their synthesis and their various potential applications, including some very comprehensive reviews of these topics. In contrast, there is a distinct lack of overview of the role the stabilizing copolymer shells have on the properties of CPNs. This review attempts to correct this oversight by scrutinizing reports detailing the synthesis and application of CPNs stabilized with some commonly-used copolymers, namely F127 (Pluronic poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) diacrylate), PSMA (poly(styrene-co-maleic anhydride)), PLGA (poly(D, L-lactide-co-glycolide)) and PEG (polyethylene glycol) derivatives. The analysis of the reported physicochemical properties and biological applications of these CPNs provides insights into the advantages of each group of copolymers for specific applications and offers a set of guidance criteria for the selection of an appropriate copolymer when designing CPNs-based probes. Finally, the challenges and outlooks in the field are highlighted.

Photoacoustic Imaging Probes for Theranostic Applications

Photoacoustic imaging (PAI), an emerging biomedical imaging technology, capitalizes on a wide range of endogenous chromophores and exogenous contrast agents to offer detailed information related to the functional and molecular content of diseased biological tissues. Compared with traditional imaging technologies, PAI offers outstanding advantages, such as a higher spatial resolution, deeper penetrability in biological tissues, and improved imaging contrast. Based on nanomaterials and small molecular organic dyes, a huge number of contrast agents have recently been developed as PAI probes for disease diagnosis and treatment. Herein, we report the recent advances in the development of nanomaterials and organic dye-based PAI probes. The current challenges in the field and future research directions for the designing and fabrication of PAI probes are proposed.

Chemical Design of Activatable Photoacoustic Probes for Precise Biomedical Applications

Photoacoustic (PA) imaging technology, a three-dimensional hybrid imaging modality that integrates the advantage of optical and acoustic imaging, has great application prospects in molecular imaging due to its high imaging depth and resolution. To endow PA imaging with the ability for real-time molecular visualization and precise biomedical diagnosis, numerous activatable molecular PA probes which can specifically alter their PA intensities upon reacting with the targets or biological events of interest have been developed. This review highlights the recent developments of activatable PA probes for precise biomedical applications including molecular detection of the biotargets and imaging of the biological events. First, the generation mechanism of PA signals will be given, followed by a brief introduction to contrast agents used for PA probe design. Then we will particularly summarize the general design principles for the alteration of PA signals and activatable strategies for developing precise PA probes. Furthermore, we will give a detailed discussion of activatable PA probes in molecular detection and biomedical imaging applications in living systems. At last, the current challenges and outlooks of future PA probes will be discussed. We hope that this review will stimulate new ideas to explore the potentials of activatable PA probes for precise biomedical applications in the future.

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.

Polypyrrole-based nanotheranostic agent for MRI guided photothermal-chemodynamic synergistic cancer therapy

Polypyrrole (PPy) nanoparticles have been widely studied in tumor photothermal therapy (PTT) for their significant photostability, good biocompatibility, and excellent photothermal performance. Herein, we report bovine serum albumin (BSA) stabilized PPy that were mineralized by MnO₂ nanozyme on the surface (PPy@BSA-MnO₂) to achieve synergistic photothermal and chemodynamic therapy (CDT) for breast cancer. In this multifunctional nanoplatform, the surface-loaded MnO₂ undergoes a redox reaction with glutathione (GSH) to generate glutathione disulfide (GSSG) and Mn²⁺. Then, Mn²⁺ can convert H₂O₂ into a highly cytotoxic ˙OH to achieve chemodynamic therapy (CDT) and possess good magnetic resonance (MR) T₁-weighted imaging capabilities to realize contrast imaging of the 4T1 tumor-bearing mouse models. In addition, PPy nanoparticles can efficiently convert near-infrared light energy into heat and achieve PTT. Most importantly, PPy@BSA-MnO₂ nanoprobes have excellent in vitro 4T1 cell-killing effect and in vivo tumor-suppressive properties. The acute toxicity assessment results indicate that PPy@BSA-MnO₂ nanoprobes have good biological safety. Therefore, the as-prepared multifunctional PPy@BSA-MnO₂ nanoprobes possess excellent performance to promote MRI-guided PTT/CDT synergistic therapy for breast cancer treatment and have extensive clinical transformation and application prospects.