Polymer Nanoparticles for Preferential Delivery of Drugs Only by Exploiting the Slightly Elevated Temperature of Cancer Cells and Real-Time Monitoring of Drug Release

Rapid proliferation and a faster rate of glycolysis in cancer cells often result in an elevated local temperature (40-43 °C) at the tumor site. Nanoparticles prepared from polymers with two lower critical solution temperatures (LCSTs) can be utilized to take advantage of this subtle temperature elevation to deliver anticancer drugs preferably to the cancer cells, thereby enhancing the overall therapeutic efficacy and reducing side effects. In this direction, we synthesized N-vinyl-2-pyrrolidone (NVP) and substituted NVP (sub-NVP: C2-NVP, C4-NVP)-based polymers with precisely controlled LCSTs by varying the ratio of NVP and sub-NVP. The first LCST (LCST1) was kept below 37 °C to promote self-assembly, drug loading, and structural stability in physiological conditions and the second LCST (LCST2) was in the range of 40-43 °C to ensure mild hyperthermia-induced drug release. Additionally, covalent attachment of tetraphenylethylene (TPE, AIEgen) resulted in aggregation-induced emission in thermoresponsive micellar nanoparticles in which TPE acted as a Förster Resonance Energy Transfer (FRET) pair with the loaded anticancer drug doxorubicin (DOX). Tracking of FRET-induced fluorescence recovery of TPE molecules was utilized to confirm the real-time thermoresponsive release of DOX from nanoparticles and eventual localization of TPE in the cytoplasm and DOX in the nucleus. In vitro cellular studies such as cytotoxicity, cellular uptake, and thermoresponsive drug release showed that the DOX-loaded polymeric nanoparticles were nontoxic to normal cells (HEK-293) but significantly more effective in cancer cells (MCF-7) at 40 °C. To our knowledge, this is the first report of preferential delivery of anticancer drugs only by exploiting the slightly elevated temperature of cancer cells.

Pyrene-Based AIE Active Materials for Bioimaging and Theranostics Applications

Aggregation-induced emission (AIE) is a unique research topic and property that can lead to a wide range of applications, including cellular imaging, theranostics, analyte quantitation and the specific detection of biologically important species. Towards the development of the AIE-active materials, many aromatic moieties composed of tetraphenylethylene, anthracene, pyrene, etc., have been developed. Among these aromatic moieties, pyrene is an aromatic hydrocarbon with a polycyclic flat structure containing four fused benzene rings to provide an unusual electron delocalization feature that is important in the AIE property. Numerous pyrene-based AIE-active materials have been reported with the AIE property towards sensing, imaging and theranostics applications. Most importantly, these AIE-active pyrene moieties exist as small molecules, Schiff bases, polymers, supramolecules, metal-organic frameworks, etc. This comprehensive review outlines utilizations of AIE-active pyrene-based materials on the imaging and theranostics studies. Moreover, the design and synthesis of these pyrene-based molecules are delivered with discussions on their future scopes.

Construction of heteroaryl-bridged NIR AIEgens for specific imaging of lipid droplets and its application in photodynamic therapy

As a kind of subcellular organelle, lipid droplets (LDs) play a critical role in the body's normal metabolism. LDs have gained increasing attention as a fluorescent photodynamic target site. Near-infrared (NIR) organic light-emitting luminescent materials, with aggregation-induced emission (AIE)-active feature, preeminent LD-imaging ability, and effective reactive oxygen species (ROS) production property, have been widely used for photodynamic therapy (PDT) in diagnostic therapeutics, but its application remains challenging. In the present work, three novel NIR organic compounds with AIE-active feature, namely, TPET-Is, TPET-Fu, and TPEF-Is, were developed and synthesized. These heteroaryl-bridged molecules possess a donor-donor-π-acceptor structure and strong intramolecular charge transfer character. These AIEgens are capable of high-fidelity LD imaging in living cells (Pearson's coefficient values: 0.94, 0.96, 0.97) due to their biocompatibility, good photostability, and strong lipophilicity (LogP values: 9.39, 7.89, 8.03), respectively. Moreover, they can be also applied in bright imaging the LDs of oil-rich plant tissues, such as those of sunflower seeds. The respective AIEgens TPET-Fu of these compounds can also produce ROS in the condition of white light to effectively kill live Hela cells. The present study thus provides a potential strategy through heteroaryl-bridged molecular engineering for LD-targeted imaging and PDT application.

Vaginal drug delivery approaches for localized management of cervical cancer

Cervical cancer or cervical intraepithelial neoplasia (CIN) remain a major public health problem among women globally. Traditional methods such as surgery are often associated with possible complications which may impact future pregnancies and childbirth especially for young female patients. Vagina with a high contact surface is a suitable route for the local and systemic delivery of drugs but its abundant mucus in continuous exchange presents a barrier for the popularization of conventional vaginal formulations including suppositories, gel, patch, creams and so on. So the development of new pharmaceutical forms based on nanotechnology became appealing owing to its several advantages such as mucosa penetration, bioadhesion, controlled drug release, and decreased adverse effects. This review provided an overview of the development of topical treatment of cervical cancer or CIN through vaginal drug delivery ranging from conventional vaginal formulations to new nanocarriers to the newly developed phototherapy and gene therapy, analyzing the problems faced by current methods used, and advising the developing trend in future. The methods of establishing preclinical animal model are also discussed.