Design of donor-acceptor conjugated polymers based on diketopyrrolopyrrole for NIR-II multifunctional imaging.

Diketopyrrolopyrrole (DPP) is an excellent photosensitizer and photothermal agent with the advantages of good planarity, strong electron affinity, high electron mobility, easy purification, easy structural modification and high molar absorption coefficient. It is regarded as one of the ideal choices for the design and synthesis of efficient organic photovoltaic materials. Therefore, two kinds of donor-acceptor (D-A) conjugated polymers were designed and synthesized with DPP as the acceptor, and their optical properties and applications in the near-infrared region were studied. The quantum yield (QY) of PBDT-DPP is 0.46%, and the highest temperature reached within 10 minutes after irradiation with a 660 nm laser is 60 °C. Another polymer, EDOT-DPP, has a QY of 0.48%, and its semiconductor polymer nanoparticle aqueous solution can reach 60 °C within 12 minutes under laser irradiation, achieving photothermal treatment of nude mice tumors. Both polymer NPs have good biocompatibility and promising applications in bioimaging and photothermal therapy.

D-A-D organic fluorescent probes for NIR-II fluorescence imaging and efficient photothermal therapy of breast cancer.

Near-infrared second region (NIR-II) fluorescent probes are used in the diagnosis of early cancer due to their high tissue penetration. However, there are still few reports on organic small molecule fluorescent probes with NIR-II fluorescence imaging (NIR-II FI) combined with efficient photothermal therapy (PTT). In this study, planar cyclopentadithiophene (CPDT) was incorporated into the twisted structural skeleton (D-A-D), and the strong acceptor TTQ molecule (A) and the donor triphenylamine (D) were introduced to synthesize an organic small molecule (TCT) with enhanced NIR-II fluorescence emission performance. To improve the hydrophilicity of TCT molecules, we used the nanoprecipitation method to coat DSPE-mPEG2000 on the TCT molecules and obtained nanoparticles (TCT-NPs) with a strong absorption band, good water dispersibility, and NIR-II FI ability, which realized NIR-II FI-guided PTT for breast cancer tumors. Due to their effective near-infrared absorption, TCT-NPs exhibit high photothermal conversion efficiency (η = 40.1%) under 660 nm laser irradiation, making them a photothermal therapeutic agent with good performance. Therefore, TCT-NPs have the potential to diagnose, eliminate, and monitor the diffusion of cancer.

Photothermal-responsive Prussian blue nanocages loaded with thrombin for tumor starvation therapy and photothermal therapy.

The goal of inhibiting tumor growth can be achieved by cutting off the supply of nutrients in the blood vessels of a tumor site, but finding ways to effectively, accurately and safely deliver drugs that can induce vascular embolism remains a challenge. Phase change materials (PCM) can undergo solid-liquid transformation at the phase change temperature. This study reports on a near-infrared ray (NIR)-responsive nano-drug delivery platform based on Prussian blue (PB) nanoparticles. The PCM (lauric acid) can encapsulate thrombin (Thr) in the Prussian blue nanocage (PB Cage), and effectively avoid the pre-leakage of Thr during blood circulation. When the (Thr/PCM)@PB Cage is accumulated at the tumor site and irradiated with NIR, the thermal effect induced by the PB Cage causes the PCM to undergo a solid-liquid state transition, rapidly releasing the encapsulated Thr and inducing coagulation in the tumor blood vessels. Based on the safe delivery and precisely controlled release of Thr, the proliferation of tumor cells can be inhibited without damaging other tissues and organs. In addition, PB Cage-induced photothermal therapy can also ablate tumor cells. Thr-induced "starvation therapy" based on PB Cage loading provides a good reference for precise controlled-release drug delivery systems.

Preparation of thrombin-loaded calcium alginate microspheres with dual-mode imaging and study on their embolic properties in vivo.

Transcatheter arterial embolization (TAE) has played a huge role in the interventional treatment of organ bleeding and accidental bleeding. Choosing bio-embolization materials with good biocompatibility is an important part of TAE. In this work, we prepared a calcium alginate embolic microsphere using high-voltage electrostatic droplet technology. The microsphere simultaneously encapsulated silver sulfide quantum dots (Ag2S QDs) and barium sulfate (BaSO4), and fixed thrombin on its surface. Thrombin can achieve an embolic effect while stopping bleeding. The embolic microsphere has good near-infrared two-zone (NIR-II) imaging and X-ray imaging effects, and the luminous effect of NIR-II is better than that of X-rays. This breaks the limitations of traditional embolic microspheres that only have X-ray imaging. And the microspheres have good biocompatibility and blood compatibility. Preliminary application results show that the microspheres can achieve a good embolization effect in the ear arteries of New Zealand white rabbits, and can be used as an effective material for arterial embolization and hemostasis. This work realizes the clinical embolization application of NIR-II combined with X-ray multimodal imaging technology in biomedical imaging, achieving complementary advantages and excellent results, more suitable for studying biological changes and clinical applications.

Donor-acceptor-donor small molecules for fluorescence/photoacoustic imaging and integrated photothermal therapy.

Here, a D-A-D type fluorescent conjugated molecule with a high molar absorption coefficient and emission at 1120 nm in the near-infrared region was synthesized. Conjugated molecules and two polyethylene glycol polymers with different lipophilic ends are assembled into water-soluble nanoparticles to improve their biocompatibility. Then, their physical and chemical properties were studied and compared. Compared with phospholipid-based PEG, styrene-based PEG can reduce the π-π stacking between molecules and the quenching caused by molecular aggregation. It has more advantages in particle size and fluorescence performance and can be better used in biological imaging. In addition, the Nano-particles have good photo-thermal conversion efficiency; the temperature rises to 62.8°C after 980 nm irradiation for 6 min, which can be used as a potential near-infrared II photothermal therapeutic agent. In vivo imaging experiments confirmed that nanomaterials have fluorescence, photoacoustic dual-modal imaging and good biological safety. STATEMENT OF SIGNIFICANCE: In this work, we constructed D-A-D type dual donor fluorescent molecules using BBTD, CPDT and EDOT, and used amphiphilic polymers to improve their biocompatibility. Compared with DSPE NPs, PS-NPs can reduce intermolecular π-π stacking and increase quantum yield (QY = 0.98 %). Deep penetration and low biological toxicity make it have biomedical value and realize the integration of multi-functional collaborative imaging. This work can still be further improved and supplemented, and the molecular structure can be optimized to improve its application in biomedical imaging.

Dual receptor NIR-II organic nanoparticles for multimodal imaging guided tumor photothermal therapy.

The second near-infrared (NIR-II) fluorescence imaging has attracted continuous attention due to its excellent penetration depth and high spatial resolution. Compared with other fluorophores, NIR-II fluorophores, especially NIR-II organic small molecule fluorophores, are favored because of their controllable structure and good biocompatibility. In this study, we designed and synthesized an S-D-A-D-S type small molecule FEA. However, a new molecule was accidentally obtained in the process of synthesis, which was proved to be a double receptor (A-A) type small molecule, namely S-D-A-A-D-S type organic small molecule FEAA. Compared with FEA molecules, FEAA exhibits superior fluorescence performance and can effectively prevent fluorescence quenching. The fluorescence emission of its nanoparticles (NPs) reaches 1109 nm, extends to about 1400 nm, and has a Stokes shift of up to 472 nm. Subsequently, we realized fluorescence/photoacoustic dual-mode imaging (FI/PAI) of nude mouse liver, and finally effectively ablated 4T1 tumor by photothermal therapy (PTT). In general, FEAA NPs exhibit good fluorescence, photoacoustic, and photothermal effects, and are an excellent multifunctional NIR-II organic small molecule fluorophore. As far as we know, there are few reports on A-A type organic small molecules, most of which are cyanines or D-A-D type structures. Therefore, this study has good exploratory significance and reference value for the discovery of NIR-II fluorophores.

Semiconductor small molecule IHIC/ITIC applied to photothermal therapy and photoacoustic imaging of tumors.

Organic semiconductor small molecules IHIC and ITIC have been developed as solar cell materials, and because of their strong near-infrared absorption capabilities, they are promising for cancer phototherapy. This article reports the application of semiconductor small molecule IHIC/ITIC liposomes in photothermal therapy and photoacoustic imaging of tumors firstly. Experiments show that the liposome-loaded IHIC/ITIC material has good biocompatibility and can be effectively enriched in tumor sites. After being irradiated with laser, it can emit strong photoacoustic signals, and has achieved good results in the photothermal treatment of breast cancer mice. We believe that organic semiconductor small molecule IHIC/ITIC will become a promising photothermal agent with wonderful development possibilities.

An overview of chitosan and its application in infectious diseases.

Infectious diseases, such as the coronavirus disease-19, SARS virus, Ebola virus, and AIDS, threaten the health of human beings globally. New viruses, drug-resistant bacteria, and fungi continue to challenge the human efficacious drug bank. Researchers have developed a variety of new antiviral and antibacterial drugs in response to the infectious disease crisis. Meanwhile, the development of functional materials has also improved therapeutic outcomes. As a natural material, chitosan possesses good biocompatibility, bioactivity, and biosafety. It has been proven that the cooperation between chitosan and traditional medicine greatly improves the ability of anti-infection. This review summarized the application and design considerations of chitosan-composed systems for the treatment of infectious diseases, looking forward to providing the idea of infectious disease therapy.

Efficient photocatalytic degradation of toxic Alizarin yellow R dye from industrial wastewater using biosynthesized Fe nanoparticle and study of factors affecting the degradation rate.

Development of highly robust and solar-light-responsive photocatalysts for the disposal of organic dyes from wastewater is a matter of great significance in order to solve the problems of water pollution. Solar-driven photocatalytic degradation of dyes is considered as a quite efficient, sustainable and cost-effective approach as it involved the inexhaustible and renewable source of energy. In photocatalytic processes, the generation of electron-hole pairs at the surface of the photocatalyst is accomplished by harvesting solar energy. The electron-hole pairs are converted into •OH radicals that are responsible for the degradation of dyes. Herein, we reported the synthesis of nanosized iron (FeNPs) using the aqueous fruit extract of Actinidia chinensis as a reducing as well as the stabilizing agent. The structure and morphology of synthesized nanoparticles were characterized using various advanced techniques. The TEM micrographs showed that the synthesized FeNPs was predominantly cubic and rod-shaped having the size in the range of 91.78-107 nm. The as-prepared FeNPs were acted as effective photocatalysts and their photocatalytic activity evaluated against alizarin yellow R (AYR) dye. The effect of different reaction conditions such as temperature, pH, time and catalyst loading on photocatalytic degradation of AYR dye was investigated under sunlight irradiation. The FeNPs showed promising photocatalytic activity and up to 93.7% of the dye was degraded in 42 h. The kinetics parameter of the reaction was also evaluated which showed that the photocatalytic degradation of AYR dye followed the pseudo-first-order reaction. In terms of better degradation, the role of FeNPs might be extended for the treatment of different organic dyes from wastewater.

D-A polymers for fluorescence/photoacoustic imaging and characterization of their photothermal properties.

NIR-II fluorescence imaging has great potential in diagnosis, but the quantum efficiency of contrast agents is an urgent problem to be solved. We synthesized two new multifunctional polymers, P-TT and P-DPP, with a tetrahedral C (sp3) and branched alkyl chains in the main chain, which were beneficial to obtain high quantum efficiency. P-TT and P-DPP showed absorption peaks of 686 nm and 763 nm, respectively, and fluorescence emission peaks of 1071 nm and 1066 nm, respectively. The photothermal effect of P-DPP can reach 52 °C, and the quantum yield reaches 1.5%, which was three times higher than that of nanotube fluorophores (quantum yield 0.4%). P-DPP is used for stable fluorescence imaging of blood vessels and photoacoustic imaging of nude mice, and successfully applied to phototherapy of nude mouse tumours.

Conjugated-Polymer-Based Nanoparticles with Efficient NIR-II Fluorescent, Photoacoustic and Photothermal Performance.

Fluorescence imaging (FI) and photoacoustic imaging (PA) play important roles in the real-time assessment of cell-based therapies. However, the limitations of conventional organic fluorescence contrast agents and the narrow range of the emission wavelength in the first near-infrared (NIR-I) window (750-900 nm) hamper applications of fluorescence imaging in living subjects. Herein, we report the design and synthesis of a short-wave infrared FI contrast agent and PA contrast agent based on a conjugated polymer-poly{2,5-bis[(5-thiophen-2-yl)methylene]-3,6-bis(2-octyldodecyl)-2,5-dihydropyrazine}-and its use to construct multifunctional nanoparticles to simplify photothermal therapy.

Organic Semiconductors for Photothermal Therapy and Photoacoustic Imaging.

In recent years, semiconducting polymer nanoparticles (SPNs) have been attracting considerable attention because of their outstanding characteristics such as higher light and thermal stability. They are widely used in fields of biomedicine such as photoacoustic (PA) imaging (PAI), photodynamic therapy (PDT), and photothermal therapy (PTT). PAI, a new imaging modality based on PA effects, shows great promise in biomedical applications. SPNs that display strong optical absorbance in the visible and near-infrared (NIR) regions can be promising candidates for in vivo PTT and PAI. Here we introduce the preparation of organic conjugated polymer fluorescent nanoparticles in the aqueous phase. We then discuss the application of water-dispersible conjugated polymer nanoparticles in PA and PTT. Finally, we discuss the opportunities and challenges for the development of organic conjugated polymer nanoparticles.

Advanced Carbon-based Nanoplatforms Combining Drug Delivery and Thermal Therapy for Cancer Treatment.

Anticancer treatment has become a research highlight in recent years. Despite several techniques have been developed and applied in the clinic, this area still meets great challenges in the construction of smart anticancer devices with accurate targeting, controlled release and microenvironment response properties. Most of the carbon-based materials are biocompatible, possessing abundant and tunable pore structures and particularly large surface areas. These properties make them suitable materials as drug carriers. In addition, some carbon-based materials are capable of absorbing near-infrared radiation (NIR) and have highly efficient photothermal effects. The generated heat in situ can be used to kill cancer cells in short time on the position. This review describes the recent and significant application of four kinds of carbon materials including carbon nanotubes, graphene, carbon dots and mesoporous carbon for drug delivery and photothermal therapy. After a short introduction of the structures and properties of these materials, the construction and application of these nanoplatforms in drug delivery, photothermal therapy or their combination will be summarized and discussed in depth. In addition, other carbon allotropes as drug carriers will be introduced briefly. Finally, the risk assessments and the perspectives and challenges of these materials used in cancer therapies are enclosed.