A pH-Sensitive Phospholipid Polymeric Prodrug Based on Branched Polyethylenimine for Intracellular Drug Delivery

Metal-Coordinated Polymer-Inorganic Hybrids: Synthesis, Properties, and Application

This review examines the recent advancements and unique properties of polymer-inorganic hybrid materials formed through coordination bonding (Class II hybrids), which enable enhanced functionality and stability across various applications. Here, we categorize these materials based on properties gained through complexation, focusing on electrical conductivity, thermal stability, photophysical characteristics, catalytic activity, and nanoscale self-assembly. Two major synthetic approaches to making these hybrids include homogeneous and heterogeneous methods, each with distinct tradeoffs: Homogeneous synthesis is straightforward but requires favorable mixing between inorganic and polymer species, which are predominantly water-soluble complexes. In contrast, heterogeneous methods are post-processing techniques that provide high area selectivity for inorganic precursors, allowing precise integration within polymer matrices. Finally, we highlight the role of hybrid linkers, namely metallosupramolecular polymers, in creating structural diversity. These can be organized into three main groups: metal-organic frameworks (MOFs), coordination polymers (CPs), and supramolecular coordination complexes (SCCs). Each of these groups introduces unique structural and functional properties that expand the potential applications of hybrid materials.

Polyethyleneimine-Based Drug Delivery Systems for Cancer Theranostics

With the development of nanotechnology, various types of polymer-based drug delivery systems have been designed for biomedical applications. Polymer-based drug delivery systems with desirable biocompatibility can be efficiently delivered to tumor sites with passive or targeted effects and combined with other therapeutic and imaging agents for cancer theranostics. As an effective vehicle for drug and gene delivery, polyethyleneimine (PEI) has been extensively studied due to its rich surface amines and excellent water solubility. In this work, we summarize the surface modifications of PEI to enhance biocompatibility and functionalization. Additionally, the synthesis of PEI-based nanoparticles is discussed. We further review the applications of PEI-based drug delivery systems in cancer treatment, cancer imaging, and cancer theranostics. Finally, we thoroughly consider the outlook and challenges relating to PEI-based drug delivery systems.

Recent Advancements in Stimuli Responsive Drug Delivery Platforms for Active and Passive Cancer Targeting

The tumor-specific targeting of chemotherapeutic agents for specific necrosis of cancer cells without affecting the normal cells poses a great challenge for researchers and scientists. Though extensive research has been carried out to investigate chemotherapy-based targeted drug delivery, the identification of the most promising strategy capable of bypassing non-specific cytotoxicity is still a major concern. Recent advancements in the arena of onco-targeted therapies have enabled safe and effective tumor-specific localization through stimuli-responsive drug delivery systems. Owing to their promising characteristic features, stimuli-responsive drug delivery platforms have revolutionized the chemotherapy-based treatments with added benefits of enhanced bioavailability and selective cytotoxicity of cancer cells compared to the conventional modalities. The insensitivity of stimuli-responsive drug delivery platforms when exposed to normal cells prevents the release of cytotoxic drugs into the normal cells and therefore alleviates the off-target events associated with chemotherapy. Contrastingly, they showed amplified sensitivity and triggered release of chemotherapeutic payload when internalized into the tumor microenvironment causing maximum cytotoxic responses and the induction of cancer cell necrosis. This review focuses on the physical stimuli-responsive drug delivery systems and chemical stimuli-responsive drug delivery systems for triggered cancer chemotherapy through active and/or passive targeting. Moreover, the review also provided a brief insight into the molecular dynamic simulations associated with stimuli-based tumor targeting.

pH-responsive polydopamine nanoparticles for photothermally promoted gene delivery

Recently, stimuli-responsive gene carriers have been widely studied to overcome the extra- and intracellular barriers in cancer treatment. In this study, we modified polydopamine nanoparticles with low-molecular weight polyethylenimine (PEI_1.8k) and polyethylene glycol-phenylboronic acid (PEG-PBA) to prepare pH-responsive gene carrier PDANP-PEI-rPEG. PBA and polydopamine could form pH-responsive boronate ester bonds. Non-responsive PDANP-PEI-nPEG and non-PEGylated PDANP-PEI were also studied as control. Both PDANP-PEI-rPEG/DNA and PDANP-PEI-nPEG/DNA complexes remained stable in the pH environment of blood circulation or extracellular delivery (pH 7.4) owing to the PEG modification. And after being internalized into endosomes, the boronate ester bonds could be cleaved. The pH responsive ability of PDANP-PEI-rPEG might facilitate complexes dissociation and gene release inside cells. The transfection level of PDANP-PEI-rPEG/DNA complexes was about 100 times higher than that of PDANP-PEI-nPEG/DNA complexes with the same mass ratios. Moreover, after NIR light irradiation at the power density of 2.6 W/cm² for 20 min, the good photothermal conversion ability of PDANP resulted in quick endosomal escape. The transfection level of PDANP-PEI-rPEG/DNA complexes doubled, even higher than that of lipofectamine 2000/DNA complexes. This was also confirmed by Bafilomycin A1 inhibition test and CLSM observation. In response to the acidic pH within cancer cells and the NIR light irradiation, the PDANP-PEI-rPEG carrier could overcome multiple obstacles in gene delivery, which was promising for further application in gene therapy.

Nucleolin-Targeting AS1411-Aptamer-Modified Graft Polymeric Micelle with Dual pH/Redox Sensitivity Designed To Enhance Tumor Therapy through the Codelivery of Doxorubicin/TLR4 siRNA and Suppression of Invasion

In this article, a novel graft polymeric micelle with targeting function ground on aptamer AS1411 was synthesized. The micelle was based on chitosan-ss-polyethylenimine-urocanic acid (CPU) with dual pH/redox sensitivity and targeting effects. This micelle was produced for codelivering Toll-like receptor 4 siRNA (TLR4-siRNA) and doxorubicin (Dox). In vitro investigation revealed the sustained gene and drug release from Dox-siRNA-loaded micelles under physiological conditions, and this codelivery nanosystem exhibited high dual pH/redox sensitivity, rapid intracellular drug release, and improved cytotoxicity against A549 cells in vitro. Furthermore, the micelles loaded with TLR4-siRNA inhibited the migration and invasion of A549. Excellent tumor penetrating efficacy was also noted in the A549 tumor spheroids and solid tumor slices. In vivo, multiple results demonstrated the excellent tumor-targeting ability of AS1411-chitosan-ss-polyethylenimine-urocanic acid (ACPU) micelle in tumor tissues. The micelles exhibited excellent antitumor efficacy and low toxicity in the systemic circulation in lung-tumor-bearing BALB/c mice. These results conclusively demonstrated the great potential of the new graft copolymer micelle with targeting function for the targeted and efficient codelivery of chemotherapeutic drugs and genes in cancer treatment.

A biomimetic fluorescent chemosensor for highly sensitive zinc(ii) detection and its application for cell imaging

To fabricate a novel biomimetic fluorescent chemosensor, PSaAEMA-co-PMPC was synthesized via atom transfer radical polymerization, and this copolymer could be used for the detection of zinc(ii) and cell imaging. A series tests with various metal ions verified the specific fluorescence response behavior. This novel biomimetic fluorescent chemosensor exhibits excellent selectivity for Zn²⁺ ions over a wide range of tested metal ions in an aqueous solution. Moreover, cytotoxicity and bio-imaging tests were conducted to study the potential bio-application of the chemosensor. Owing to the biomimetic portion (phosphorylcholine), this copolymer possesses outstanding biocompatibility and could clearly image cells. The results indicated that PSaAEMA-co-PMPC has great potential for application in zinc(ii) detection and cell imaging.

To fabricate a novel biomimetic fluorescent chemosensor, PSaAEMA-co-PMPC was synthesized via atom transfer radical polymerization, and this copolymer could be used for the detection of zinc(ii) and cell imaging.