Amphiphilic Block Copolymers Containing Benzenesulfonyl Azide Groups as Visible Light-Responsive Drug Carriers for Image-Guided Delivery.

Nanoparticles (NPs) containing light-responsive polymers and imaging agents show great promise for controlled drug delivery. However, most light-responsive NPs rely on short-wavelength excitation, resulting in poor tissue penetration and potential cytotoxicity. Moreover, excessively sensitive NPs may prematurely release drugs during storage and circulation, diminishing their efficacy and causing off-target toxicity. Herein, we report visible-light-responsive NPs composed of an amphiphilic block copolymer containing responsive 4-acrylamide benzenesulfonyl azide (ABSA) and hydrophilic N,N'-dimethylacrylamide (DMA) units. The polymer pDMA-ABSA was loaded with the chemotherapy drug dasatinib and zinc tetraphenylporphyrin (ZnTPP). ZnTPP acted as an imaging reagent and a photosensitizer to reduce ABSA upon visible light irradiation, converting hydrophobic units to hydrophilic units and disrupting NPs to trigger drug release. These NPs enabled real-time fluorescence imaging in cells and exhibited synergistic chemophotodynamic therapy against multiple cancer cell lines. Our light-responsive NP platform holds great promise for controlled drug delivery and cancer theranostics, circumventing the limitations of traditional photosensitive nanosystems.

Light-mediated intracellular polymerization.

The synthesis of synthetic intracellular polymers offers groundbreaking possibilities in cellular biology and medical research, allowing for novel experiments in drug delivery, bioimaging and targeted cancer therapies. These macromolecules, composed of biocompatible monomers, are pivotal in manipulating cellular functions and pathways due to their bioavailability, cytocompatibility and distinct chemical properties. This protocol details two innovative methods for intracellular polymerization. The first one uses 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959) as a photoinitiator for free radical polymerization under UV light (365 nm, 5 mW/cm2). The second method employs photoinduced electron transfer-reversible addition-fragmentation chain-transfer polymerization with visible light (470 nm, 100 mW/cm2). We further elaborate on isolating these intracellular polymers by streptavidin/biotin interaction or immobilized metal ion affinity chromatography for polymers tagged with biotin or histidine. The entire process, from polymerization to isolation, takes ~48 h. Moreover, the intracellular polymers thus generated demonstrate significant potential in enhancing actin polymerization, in bioimaging applications and as a novel avenue in cancer treatment strategies. The protocol extends to animal models, providing a comprehensive approach from cellular to systemic applications. Users are advised to have a basic understanding of organic synthesis and cell biology techniques.

In situ densification and heparin immobilization of bacterial cellulose vascular patch for potential vascular applications.

Nowadays, developing vascular grafts (e.g., vascular patches and tubular grafts) is challenging. Bacterial cellulose (BC) with 3D fibrous network has been widely investigated for vascular applications. In this work, different from BC vascular patch cultured with the routine culture medium, dopamine (DA)-containing culture medium is employed to in situ synthesize dense BC fibrous structure with significantly increased fiber diameter and density. Simultaneously, BC fibers are modified by DA during in situ synthesis process. Then DA on BC fibers can self-polymerize into polydopamine (PDA) accompanied with the removal of bacteria in NaOH solution, obtaining PDA-modified dense BC (PDBC) vascular patch. Heparin (Hep) is subsequently covalently immobilized on PDBC fibers to form Hep-immobilized PDBC (Hep@PDBC) vascular patch. The obtained results indicate that Hep@PDBC vascular patch exhibits remarkable tensile and burst strength due to its dense fibrous structure. More importantly, compared with BC and PDBC vascular patches, Hep@PDBC vascular patch not only displays reduced platelet adhesion and improved anticoagulation activity, but also promotes the proliferation, adhesion, spreading, and protein expression of human umbilical vein endothelial cells, contributing to the endothelialization process. The combined strategy of in situ densification and Hep immobilization provides a feasible guidance for the construction of BC-based vascular patches.

Ultrasound-responsive glycopolymer micelles for targeted dual drug delivery in cancer therapy.

Controlled drug release of nanoparticles was achieved by irreversibly disrupting polymer micelles through high-intensity focused ultrasound (HIFU) induction. An ultrasound-responsive block copolymer was synthesized, comprising an end-functional Eosin Y fluorophore, 2-tetrahydropyranyl acrylate (THPA), and acrylate mannose (MAN). The block copolymer was then self-assembled to produce micelles. The chemotherapy drug dasatinib (DAS) and the sonodynamic therapy agent methylene blue (MB) were encapsulated by the self-assembly of the block copolymer. This targeted nanoparticle enables sonodynamic therapy through high-intensity focused ultrasound while triggering nanoparticle disassembly for controlled drug release. The ultrasound-mediated, non-invasive strategy provides external spatiotemporal control for targeted tumour treatment.

Multifunctional, histidine-tagged polymers: antibody conjugation and signal amplification.

A polymer scaffold, with multiple reactive centres, was synthesised by RAFT polymerisation and conjugated to the antibody herceptin. A hexahistidine RAFT agent enabled the rapid and simple purification of polymer-protein conjugates, while the tetrazine conjugation strategy allows myriad cargos to be attached and amplified.

Synthetic Polymers Provide a Robust Substrate for Functional Neuron Culture.

Substrates for neuron culture and implantation are required to be both biocompatible and display surface compositions that support cell attachment, growth, differentiation, and neural activity. Laminin, a naturally occurring extracellular matrix protein is the most widely used substrate for neuron culture and fulfills some of these requirements, however, it is expensive, unstable (compared to synthetic materials), and prone to batch-to-batch variation. This study uses a high-throughput polymer screening approach to identify synthetic polymers that supports the in vitro culture of primary mouse cerebellar neurons. This allows the identification of materials that enable primary cell attachment with high viability even under "serum-free" conditions, with materials that support both primary cells and neural progenitor cell attachment with high levels of neuronal biomarker expression, while promoting progenitor cell maturation to neurons.

Radical polymerization inside living cells.

Polymerization reactions conducted inside cells must be compatible with the complex intracellular environment, which contains numerous molecules and functional groups that could potentially prevent or quench polymerization reactions. Here we report a strategy for directly synthesizing unnatural polymers in cells through free radical photopolymerization using a number of biocompatible acrylic and methacrylic monomers. This offers a platform to manipulate, track and control cellular behaviour by the in cellulo generation of macromolecules that have the ability to alter cellular motility, label cells by the generation of fluorescent polymers for long-term tracking studies, as well as generate a variety of nanostructures within cells. It is remarkable that free radical polymerization chemistry can take place within such complex cellular environments. This demonstration opens up a multitude of new possibilities for how chemists can modulate cellular function and behaviour and for understanding cellular behaviour in response to the generation of free radicals.