Croconaine-Based Polymer Particles as Contrast Agents for Photoacoustic Imaging

A croconic acid-derived narrow band gap conjugated microporous polymer

Croconic acid, a novel highly electron-deficient building block, was introduced into a conjugated microporous polymer (CTPA). The CMP possesses strong donor-acceptor interactions, which resulted in near-IR absorption (red edge ∼1350 nm), a narrow bandgap (<1 eV) and high electrical conductivity upon doping (0.1 S m^-1). Compared to the squaric acid congener (STPA), CTPA showed superior optical, electronic and electrical properties.

Fe(III)-Doped Polyaminopyrrole Nanoparticle for Imaging-Guided Photothermal Therapy of Bladder Cancer

Clinically, the surgical treatment of bladder cancer often faces the problem of tumor recurrence, and the surgical treatment combined with postoperative chemotherapy to inhibit tumor recurrence also faces high toxicity and side effects. Therefore, the need for innovative bladder cancer treatments is urgent. For the past few years, with the development of nano science and technology, imaging-guided therapy using nanomaterials with both imaging and therapy functions has shown great advantages and can not only identify the locations of the tumors but also exhibit biodistributions of nanomaterials in the tumors, significantly improving the accuracy and efficacy of treatment. In this work, we synthesized Fe(III)-doped polyaminopyrrole nanoparticles (FePPy-NH₂ NPs). With low cytotoxicity and a blood circulation half-life of 7.59 h, high levels of FePPy-NH₂ NPs accumulated in bladder tumors, with an accumulation rate of up to 5.07%ID/g. The coordination of Fe(III) and the amino group in the structure can be used for magnetic resonance imaging (MRI), whereas absorption in the near-infrared region can be applied to photoacoustic imaging (PAI) and photothermal therapy (PTT). MRI and PAI accurately identified the location of the tumor, and based on the imaging data, laser irradiation was employed accurately. With a high photothermal conversion efficiency of 44.3%, the bladder tumor was completely resected without recurrence. Hematological analysis and histopathological analysis jointly confirmed the high level of safety of the experiment.

Acoustic Standing Wave Aided Multiparametric Photoacoustic Imaging Flow Cytometry

Photoacoustic imaging reveals great potential for the study of individual cells due to the rich imaging contrast for both label-free and labeled cells. However, previously reported photoacoustic imaging flow cytometry configuration suffers from inadequate imaging quality and challenge to distinguish multiple cells. In order to solve such issues, we propose a novel acoustic standing wave aided multiparametric photoacoustic imaging flow cytometry (MPAFC) system. The acoustic standing wave is introduced to improve the imaging quality and speed. Multispectral illumination along with cell geometry, photoacoustic amplitude, and acoustic frequency spectrum enables the proposed system to precisely identify multiple types of cells with one scanning. On the basis of the identification, elimination of melanoma cells, and targeted labeled glioma cells have been performed with an elimination efficiency of >95%. Additionally, the MPAFC system is able to image and capture melanoma cells at a lowest concentration of 100 cells mL^-1 in pure blood. Current results suggest that the proposed MPAFC may provide a precise and efficient tool for cell detection, manipulation, and elimination in both fundamental and clinical studies.