Nanocomposites of Molybdenum Disulfide/Methoxy Polyethylene Glycol-co-Polypyrrole for Amplified Photoacoustic Signal

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.

One-step synthesis of well-dispersed polypyrrole copolymers under gamma-ray irradiation

Herein, we report for the first time the synthesis of polypyrrole copolymers with good solvent-dispersibility under gamma-ray irradiation at room temperature in air.

Molybdenum-based hetero-nanocomposites for cancer therapy, diagnosis and biosensing application: Current advancement and future breakthroughs

In recent years, there have been significant advancements in the nanotechnology for cancer therapy. Even though molybdenum disulphide (MoS2)-based nanocomposites demonstrated extensive applications in biosensing, bioimaging, phototherapy, the review article focusing on MoS2 nanocomposite platform has not been accounted for yet. The review summarizes recent strategies on design and fabrication of MoS2-based nanocomposites and their modulated properties in cancer treatment. The review also discussed several therapeutic strategies (photothermal, photodynamic, immunotherapy, gene therapy and chemotherapy) and their combinations for efficient cancer therapy along with certain case studies. The review also inculcates various diagnostic techniques viz. magnetic resonance imaging, computed tomography, photoacoustic imaging and fluorescence imaging for diagnosis of cancer.

Photothermal inactivation of methicillin-resistant Staphylococcus aureus: anti-biofilm mediated by a polypyrrole-carbon nanocomposite

Widespread resistance to antibiotics amongst pathogens has become a tremendous challenge of high morbidity and mortality rates which increases the needs to exploring novel methods of treatment. An efficient antimicrobial procedure to root out pathogenic bacteria is photothermal therapy. In this study, antimicrobial effects of a polypyrrole-carbon nanocomposite (PPy-C) upon laser irradiation in order to destroy the pathogenic gram-positive bacterium, methicillin-resistant Staphylococcus aureus (MRSA) were assessed. The bacterial cells were incubated with 500, 750 and 1000 μg ml-1 concentrations of PPy-C and irradiated with an 808-nm laser at a power density of 1.0 W cm-2. To indicate the biocompatibility and toxic effect of the nanocomposite without and with laser irradiation, the authors counted the number of CFUs and compared it to an untreated sample. Antibacterial mechanisms of PPy-C were assessed through temperature increment, reactive oxygen species production, and protein and DNA leakages. Photothermal heating assay showed that 26°C temperature increases in the presence of 1000 µg ml-1 PPy-C led to >98% killing of MRSA. Furthermore, 20 min radiation of near-infrared light to PPy-C in different concentrations indicated destruction and reduction in the MRSA biofilm formation. Therefore, PPy-C was introduced as a photothermal absorber with a bactericidal effect in MRSA.

Nanocomposite Synthesis of Nanodiamond and Molybdenum Disulfide

A chemically conjugated nanodiamond (ND)/MoS2 nanocomposite was synthesized with amine-functionalized MoS2 and acyl chloride-coordinated ND. The chemical structure and morphology of the nanocomposite were characterized to examine the dispersion of MoS2 on the ND platform. The results revealed that the degree of dispersion was enhanced with increasing ratio of MoS2 nanosheets to ND. Moreover, the nanosheets consisted of several molecular interlayers that were well-dispersed on the ND platform, thereby forming a nanophase. The efficient electrocapacity of the ND/MoS2 nanocomposite was considerably greater than that of the MoS2 electrode alone. Furthermore, the nanophase distribution of MoS2 on ND with a graphitic shell provided a large surface area and reduced the diffusion distance of ions and electrons. Therefore, the nanophase electrode showed higher electrochemical capacitance than that of the MoS2 electrode alone.

Drug Delivery System Based on Near-Infrared Light-Responsive Molybdenum Disulfide Nanosheets Controls the High-Efficiency Release of Dexamethasone To Inhibit Inflammation and Treat Osteoarthritis

Intra-articular injection has unique advantages in the treatment of osteoarthritis (OA), although it risks rapid clearance of the therapeutic drugs in the joint cavity. Combining therapeutic agents with functionalized nanocarriers may provide an effective solution. Controlling the therapeutic concentration of the drug in the joint cavity through the drug-loading nanosystem can synergistically treat OA. Here, we proposed an intra-articular drug delivery nanosystem MoS₂@CS@Dex (MCD), using the chitosan (CS)-modified molybdenum disulfide (MoS₂) nanosheets as near-infrared (NIR) photo-responsive carriers, loaded with the anti-inflammatory drug dexamethasone (Dex). MCD responded to NIR light both in vitro and in vivo and triggered Dex release through photothermal conversion. This enabled the remote-controlled Dex release in the joint cavity by adjusting the radiation behavior of the NIR light. MCD prolonged the residence time of Dex in the joint cavity. The intra-articular injection of MCD in combination with NIR radiation ensured a significant increase in the therapeutic effect of Dex at low systemic doses, which attenuated the cartilage erosion in the OA caused by the secretion of inflammatory factors including TNF-α and IL-1β. The toxicity and side effects on other internal organs during metabolism were reduced in the body. In addition, the photoacoustic imaging capability of MoS₂ nanosheets was used to detect the metabolism of MCD in the joint cavity. Our research indicated that MCD has great potential to treat OA.

Gold-implanted plasmonic quartz plate as a launch pad for laser-driven photoacoustic microfluidic pumps

A revolutionary microfluidic pump is demonstrated; it has no moving parts and no electrical contacts. It consists of a quartz plate implanted by Au particles where every point on the plate can function as a micropump. The pump is driven by a laser beam and is based on the discovered principle of photoacoustic laser streaming. When a pulsed laser hits the plate, it is absorbed by Au nanoparticles that generate an ultrasound wave, which then drives the fluid via acoustic streaming. Because laser beams can be arbitrarily patterned and timed, the fluid can be controlled by laser in a fashion similar to musical water fountains. Such a laser-driven photoacoustic micropump will find wide applications in microfluidics and optofluidics.

Enabled initially by the development of microelectromechanical systems, current microfluidic pumps still require advanced microfabrication techniques to create a variety of fluid-driving mechanisms. Here we report a generation of micropumps that involve no moving parts and microstructures. This micropump is based on a principle of photoacoustic laser streaming and is simply made of an Au-implanted plasmonic quartz plate. Under a pulsed laser excitation, any point on the plate can generate a directional long-lasting ultrasound wave which drives the fluid via acoustic streaming. Manipulating and programming laser beams can easily create a single pump, a moving pump, and multiple pumps. The underlying pumping mechanism of photoacoustic streaming is verified by high-speed imaging of the fluid motion after a single laser pulse. As many light-absorbing materials have been identified for efficient photoacoustic generation, photoacoustic micropumps can have diversity in their implementation. These laser-driven fabrication-free micropumps open up a generation of pumping technology and opportunities for easy integration and versatile microfluidic applications.

2D transition metal dichalcogenide nanosheets for photo/thermo-based tumor imaging and therapy

Two-dimensional (2D) graphene-like nanomaterials show wide applications in the fields of nanodevices, sensors, energy materials, catalysis, drug delivery, bioimaging, and tissue engineering. Recently, many studies have been focused on the synthesis and application of 2D transition metal dichalcogenide (TMD) nanosheets for various biomedical applications. In particular, 2D TMD nanosheets exhibit great advantages for tumor imaging and therapy compared to some traditional nanomaterials due to their high specific surface area, good biocompatibility, easy modification, and ultrahigh light and heat conversion efficiency. In this review, we summarize the recent advances in the synthesis, modification, and photo/thermo-based tumor imaging and therapy of 2D TMD nanosheets. The important studies on tumor bioimaging with TMD nanosheets, such as X-ray computed tomography, magnetic resonance imaging, and photoacoustic imaging, are demonstrated and discussed. In another section, the physical photothermal and photodynamic therapies as well as the pharmacological therapy of tumors with TMD nanosheet-based nanohybrids are introduced. It is expected that this work will be valuable for readers to understand the synthesis and modification of TMD nanosheets to design novel 2D functional nanomaterials for photo/thermo-based tumor imaging and therapy in one aspect, and in another aspect will extend the applications of TMD-based nanomaterials in materials science, analytical science, electrocatalysis, tissue engineering, and others.

Synthesis and Optimization of MoS2@Fe3O4-ICG/Pt(IV) Nanoflowers for MR/IR/PA Bioimaging and Combined PTT/PDT/Chemotherapy Triggered by 808 nm Laser

Elaborately designed biocompatible nanoplatforms simultaneously achieving multimodal bioimaging and therapeutic functions are highly desirable for modern biomedical applications. Herein, uniform MoS2 nanoflowers with a broad size range of 80-180 nm have been synthesized through a facile, controllable, and scalable hydrothermal method. The strong absorbance of MoS2 nanoflowers at 808 nm imparts them with high efficiency and stability of photothermal conversion. Then a novel multifunctional composite of MoS2@Fe3O4-ICG/Pt(IV) (labeled as Mo@Fe-ICG/Pt) is designed by covalently grafting Fe3O4 nanoparticles with polyethylenimine (PEI) functionalized MoS2, and then loading indocyanine green molecules (ICG, photosensitizers) and platinum (IV) prodrugs (labeled as Pt(IV) prodrugs) on the surface of MoS2@Fe3O4. The resulting Mo@Fe-ICG/Pt nanocomposites can achieve excellent magnetic resonance/infrared thermal/photoacoustic trimodal biomaging as well as remarkably enhanced antitumor efficacy of combined photothermal therapy, photodynamic therapy, and chemotherapy triggered by a single 808 nm NIR laser, thus leading to an ideal nanoplatform for cancer diagnosis and treatment in future.