Near infrared dye-labelled polymeric micro- and nanomaterials: in vivo imaging and evaluation of their local persistence

Fluorescent labeling as a strategy to evaluate uptake and transport of polymeric nanoparticles in plants

The use of biodegradable nanopolymers in agriculture offers an excellent alternative for the efficient delivery of agrochemicals that promote plant protection and development. However, tracking of these systems inside plants requires complex probe tagging strategies. In addition to providing a basis for better understanding such nanostructures to optimize delivery system design, these probes allow monitoring the migration of nanoparticles through plant tissues, and determine accumulation sites. Thus, these probes are powerful tools that can be used to quantify and visualize nanoparticle accumulation in plant cells and tissues. This review is an overview of the methods involved in labeling nanocarriers, mainly based on polymeric matrices, for the delivery of nanoagrochemicals and the recent advances in this field.

Degradable polymeric nanomaterials with a high solid content and multiple morphologies by polymerization-induced self-assembly

The preparation of degradable polymeric nanomaterials with a high solid content and multiple morphologies is highly desirable but still challenging. Here, the RAFT dispersion polymerization of styrene and 5,6-benzo-2-methylene-1,3-dioxepane was demonstrated to achieve various morphologies, including spheres, vesicles, worms, and large compound vesicles, with a high solid content through polymerization-induced self-assembly, which opens up a new avenue for the preparation of degradable polymeric nanomaterials.

Carrier-free nanoparticles of camptothecin prodrug for chemo-photothermal therapy: the making, in vitro and in vivo testing

Background

Nanoscale drug delivery systems have emerged as broadly applicable approach for chemo-photothermal therapy. However, these nanoscale drug delivery systems suffer from carrier-induced toxicity, uncontrolled drug release and low drug carrying capacity issues. Thus, to develop carrier-free nanoparticles self-assembled from amphiphilic drug molecules, containing photothermal agent and anticancer drug, are very attractive.

Results

In this study, we conjugated camptothecin (CPT) with a photothermal agent new indocyanine green (IR820) via a redox-responsive disulfide linker. The resulting amphiphilic drug–drug conjugate (IR820-SS-CPT) can self-assemble into nanoparticles (IR820-SS-CPT NPs) in aqueous solution, thus remarkably improving the membrane permeability of IR820 and the aqueous solubility of CPT. The disulfide bond in the IR820-SS-CPT NPs could be cleaved in GSH rich tumor microenvironment, leading to the on demand release of the conjugated drug. Importantly, the IR820-SS-CPT NPs displayed an extremely high therapeutic agent loading efficiency (approaching 100%). Besides, in vitro experimental results indicated that IR820-SS-CPT NPs displayed remarkable tumor cell killing efficiency. Especially, the IR820-SS-CPT NPs exhibited excellent anti-tumor effects in vivo. Both in vitro and in vivo experiments were conducted, which have indicated that the design of IR820-SS-CPT NPs can provide an efficient nanotherapeutics for chemo-photothermal therapy.

Conclusion

A novel activatable amphiphilic small molecular prodrug IR820-SS-CPT has been developed in this study, which integrated multiple advantages of GSH-triggered drug release, high therapeutic agent content, and combined chemo-photothermal therapy into one drug delivery system.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01093-y.

Fluorescent labeling of biocompatible block copolymers: synthetic strategies and applications in bioimaging

Among biocompatible materials, block copolymers (BCPs) possess several advantages due to the control of their chemistry and the possibility of combining various blocks with defined properties. Consequently, BCPs drew considerable attention as biocompatible materials in the fields of drug delivery, medicine and bioimaging. Fluorescent labeling of BCPs quickly appeared to be a method of choice to image and track these materials in order to better understand the nature of their interactions with biological media. However, incorporating fluorescent markers (FM) into BCPs can appear tricky; we thus intend to help chemists in this endeavor by reviewing recent advances made in the last 10 years. With the choice of the FM being of prior importance, we first reviewed their photophysical properties and functionalities for optimal labeling and imaging. In the second part the different chemical approaches that have been used in the literature to fluorescently label BCPs have been reviewed. We also report and discuss relevant applications of fluorescent BCPs in bioimaging.

Noninvasive and real-time pharmacokinetics imaging of polymeric nanoagents in the thoracoepigastric vein networks of living mice

Noninvasive and real-time visualization of the thoracoepigastric veins (TVs) of living mice was demonstrated by using two-photon excitation (TPE) optical imaging with a Eu-luminescent polymeric nanoagent as the angiographic contrast. The spatiotemporal evolution of the polymeric nanoagent in TVs was monitored for up to 2 h by TPE time-resolved (TPE-TR) bioimaging, which is free from the interference of tissue autofluorescence. A wide field-of-view covering the thoracoabdominal region allowed the visualization of the entire TV network with an imaging depth of 1 to 2 mm and a lateral resolution of 80 μm at submillimeter. Detailed analysis of the uptake, transport, and clearance processes of the polymeric nanoagent revealed a clearance time constant of ∼30  min and an apparent clearance efficiency of 80% to 90% for the nanoagent in both axial and lateral TVs. TPE-TR imaging of the dissected internal organs proved that the liver is mainly responsible for the sequestration of the nanoagent, which is consistent with the apparent retention efficiency of liver, ∼32  %  , as determined by the real-time in vivo TV imaging. We demonstrate the potency of TPE-TR modality in the pharmacokinetics imaging of the peripheral vascular systems of animal models, which can be beneficial for related nanotheranostics study.

Hyperbranched poly(ether amine) nanomicelles as nanoreactors for the unexpected ultrafast photolysis of fluorescein dyes

hPEA nanomicelles can encapsulate fluorescein dyes as a nanoreactor, leading to the fast photobleaching of dyes.