Jingqin Chen

Improvement of electrochemical properties of PTMA cathode by using carbon blacks with high specific surface area

A PTMA (poly(4-methacryloyloxy-2,2,6,6-tetramethyl-piperidine-N-oxyl)) electrode with high energy density is prepared with Black Pearl 2000 (BP-2000). For comparisons, vapor grown carbon fiber (VGCF) and acetylene black (AB) are also employed to fabricate the PTMA-electrodes. The electrochemical properties of the electrode are improved obviously by employing BP-2000. The specific capacity of the PTMA-BP electrode based on the mass of PTMA is 26.7% larger than that of the PTMA-VGCF and PTMA-AB electrodes at a 1 C rate. At higher discharge rates, the polarization degree of the Li/PTMA-BP cell is the minimum one. At a discharge rate of 50 C, the specific capacity of the PTMA-BP electrode is 104.9 mA h g−1, and is 27.6 and 16.7% larger than that of the PTMA-VGCF and PTMA-AB electrodes, respectively. Besides, the discharge plateau of the Li/PTMA-BP cell is 3.35 V, and is 0.03 and 0.13 V higher than that of the Li/PTMA-AB and Li/PTMA-VGCF cells, respectively. The larger specific capacity of BP-2000 and the improved electrochemical kinetics of PTMA at the surface of BP carbon, resulted from the larger surface area of BP-2000, are the main factors for improving the capacity and rate capability of the PTMA-electrode. The high specific surface area of BP-2000 is also beneficial to the thorough contact of PTMA with BP carbon, resulting in the improved conductivity of the PTMA-BP composites. The cycling performance of the PTMA-BP electrode is also satisfied.

Advances in Imaging Techniques and Genetically Encoded Probes for Photoacoustic Imaging.

Photoacoustic (PA) imaging is a rapidly emerging biomedical imaging modality that is capable of visualizing cellular and molecular functions with high detection sensitivity and spatial resolution in deep tissue. Great efforts and progress have been made on the development of various PA imaging technologies with improved resolution and sensitivity over the past two decades. Various PA probes with high contrast have also been extensively developed, with many important biomedical applications. In comparison with chemical dyes and nanoparticles, genetically encoded probes offer easier labeling of defined cells within tissues or proteins of interest within a cell, have higher stability in vivo, and eliminate the need for delivery of exogenous substances. Genetically encoded probes have thus attracted increasing attention from researchers in engineering and biomedicine. In this review, we aim to provide an overview of the existing PA imaging technologies and genetically encoded PA probes, and describe further improvements in PA imaging techniques and the near-infrared photochromic protein BphP1, the most sensitive genetically encoded probe thus far, as well as the potential biomedical applications of BphP1-based PA imaging in vivo.

Hybrid MoSe2–indocyanine green nanosheets as a highly efficient phototheranostic agent for photoacoustic imaging guided photothermal cancer therapy

Phototheranostic technology based on photoacoustic imaging (PAI) and photothermal therapy (PTT) is emerging as a powerful tool for tumor theranostic applications. For effective tumor eradication, a novel PAI/PTT theranostic nanoagent with an excellent optical absorption and photothermal capability is highly desired. Herein, we present a new PAI/PTT nanohybrid named sMoSe2-ICG NSs by covalently conjugating aminated indocyanine green (ICG) onto a single layer of molybdenum selenide nanosheets (sMoSe2 NSs). We first validate the sMoSe2-ICG NS agent for the PAI and PTT effect in vitro and then use it for highly-sensitive PAI guided highly efficient tumor PTT in vivo. The sMoSe2-ICG NS hybrid possesses several advantages for PAI/PTT applications: (1) the sMoSe2-ICG NSs have strong absorbance in the broad near-infrared (NIR) region, enabling a highly efficient PAI/PTT theranostic effect and the selection of the most widely used excitation wavelength of 808 nm for PTT; (2) the photothermal ability of ICG in sMoSe2-ICG NSs is augmented due to ICG aggregation induced fluorescence quenching and the re-absorbance of ICG fluorescence by sMoSe2 NSs, which further enhances the PAI/PTT theranostic effect. (3) The characteristic absorption peak of sMoSe2-ICG NSs is red-shifted compared to free ICG, resulting in a higher PAI signal-to-noise ratio (SNR) in vivo. Thus, combined with the good stability, high biocompatibility and minimal toxicity properties, the obtained sMoSe2-ICG NSs hybrid has bright prospects for use in future PAI/PTT clinical applications.

Focused Ultrasound-Augmented Delivery of Biodegradable Multifunctional Nanoplatforms for Imaging-Guided Brain Tumor Treatment

Abstract The blood brain barrier is the main obstacle to delivering diagnostic and therapeutic agents to the diseased sites of brain. It is still of great challenge for the combined use of focused ultrasound (FUS) and theranostic nanotechnology to achieve noninvasive and localized delivery of chemotherapeutic drugs into orthotopic brain tumor. In this work, a unique theranostic nanoplatform for highly efficient photoacoustic imaging‐guided chemotherapy of brain tumor both in vitro and in vivo, which is based on the utilization of hollow mesoporous organosilica nanoparticles (HMONs) to integrate ultrasmall Cu2− xSe particles on the surface and doxorubicin inside the hollow interior, is synthesized. The developed multifunctional theranostic nanosystems exhibit tumor‐triggered programmed destruction due to the reducing microenvironment‐responsive cleavage of disulfide bonds that are incorporated into the framework of HMONs and linked between HMONs and Cu2− xSe, resulting in tumor‐specific biodegradation and on‐demand drug‐releasing behavior. Such tumor microenvironment‐responsive biodegradable and biocompatible theranostic nanosystems in combination with FUS provide a promising delivery nanoplatform with high performance for orthotopic brain tumor imaging and therapy.

Ultrasmall hybrid protein-copper sulfide nanoparticles for targeted photoacoustic imaging of orthotopic hepatocellular carcinoma with a high signal-to-noise ratio.

Although photoacoustic imaging combined with second near infrared (NIR II) molecular probes for tumor diagnosis has drawn tremendous attention during the past few decades, the targeted photoacoustic imaging of orthotopic hepatocellular carcinoma (HCC) still remains a challenge due to high liver vascularization and non-specificity of probes in liver tumors. Herein, we report on cyclic arginine-glycine-aspartic acid (cRGD) peptide conjugated ultrasmall CuS nanoparticles (CuS@BSA-RGD NPs) which encapsulate bovine serum albumin (BSA) and possess high optical absorption at 1064 nm. The encapsulation of BSA results in great biocompatibility of CuS@BSA-RGD NPs along with excellent photostability and physiological stability. The cRGD conjugation enables the improvement of tumor uptake of CuS@BSA-RGD NPs by virtue of its positive tumor cell targeting capability. The efficient accumulation of CuS@BSA-RGD NPs in the tumor over time after intravenous administration to orthotopic HCC bearing mice was achieved, which resulted in highly sensitive photoacoustic visualization of the tumor region. Toxicity studies indicate that CuS@BSA-RGD NPs exhibited negligible systemic toxicity in vivo. The results demonstrate that the CuS@BSA-RGD NPs might hold great promise for future imaging and diagnosis of cancer.