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In this study, we synthesized two conjugated microporous polymers (CMPs), An-Ph-TPA and An-Ph-Py CMPs, using the Suzuki cross-coupling reaction. These CMPs are organic polymers with p-conjugated skeletons and persistent micro-porosity and contain anthracene (An) moieties linked to triphenylamine (TPA) and pyrene (Py) units. We characterized the chemical structures, porosities, thermal stabilities, and morphologies of the newly synthesized An-CMPs using spectroscopic, microscopic, and N 2 adsorption/desorption isotherm techniques. Our results from thermogravimetric analysis (TGA) showed that the An-Ph-TPA CMP displayed better thermal stability with T d10 = 467 °C and char yield of 57 wt% compared to the An-Ph-Py CMP with T d10 = 355 °C and char yield of 54 wt%. Furthermore, we evaluated the electrochemical performance of the An-linked CMPs and found that the An-Ph-TPA CMP had a higher capacitance of 116 F g -1 and better capacitance stability of 97% over 5000 cycles at 10 A g -1 . In addition, we assessed the biocompatibility and cytotoxicity of An-linked CMPs using the MTT assay and a live/dead cell viability assay and observed that they were non-toxic and biocompatible with high cell viability values after 24 or 48 h of incubation. These findings suggest that the An-based CMPs synthesized in this study have potential applications in electrochemical testing and the biological field.

Gene-based therapies have emerged as a new modality for combating a myriad of currently incurable diseases. However, the fragile nature of gene therapeutics has significantly hampered their biomedical applications. Correspondingly, the development of gene-delivery vectors is of critical importance for gene-based therapies. To date, a variety of gene-delivery vectors have been created and utilized for gene delivery. In general, they can be categorized into viral- and non-viral vectors. Due to safety issues associated with viral vectors, non-viral vectors have recently attracted much more research focus. Of these non-viral vectors, polymeric vectors, which have been preferred due to their low immunogenicity, ease of production, controlled chemical composition and high chemical versatility, have constituted an ideal alternative to viral vectors. In particular, biodegradable polymers, which possess advantageous biocompatibility and biosafety, have been considered to have great potential in clinical applications. In this context, the aim of this review is to introduce the recent development and progress of biodegradable polymers for gene delivery applications, especially for their chemical structure design, gene delivery capacity and additional biological functions. Accordingly, we first define and categorize biodegradable polymers, followed by describing their corresponding degradation mechanisms. Various types of biodegradable polymers resulting from natural and synthetic polymers will be introduced and their applications in gene delivery will be examined. Finally, a future perspective regarding the development of biodegradable polymer vectors will be given., Competing Interests: The authors report no conflicts of interest in this work., (© 2020 Chen et al.)

Poly[2-( tert-butylaminoethyl) methacrylate] (PTA), an important class of antimicrobial polymers, has demonstrated its great biocidal efficiency, favorable nontoxicity, and versatile applicability. To further enhance its antimicrobial efficiency, an optimization of the chemical structure of PTA polymers is performed via atom transfer radical polymerization (ATRP) in terms of the antimicrobial ability against Escherichia coli ( E. coli) and Staphylococcus aureus ( S. aureus). After the optimization, the resulting PTA is blended into a polylactide (PLA) matrix to form PTA/PLA composite thin films. It is first found, that the antimicrobial efficiency of PTA/PLA composites was significantly enhanced by controlling the PLA crystallinity and the PLA spherulite size. A possible mechanistic route regarding this new finding has been rationally discussed. Lastly, the cytotoxicity and mechanical properties of a PTA/PLA composite thin film exhibiting the best biocidal effect are evaluated for assessing its potential as a new material for creating antimicrobial biomedical devices.

Chitosan/poly(vinyl alcohol) (CS/PVA) hybrid nanofibers via electrospinning have been extensively used as wound dressing materials. However, there are still several drawbacks associated with their processing procedures and material properties, including the necessity of using acid solutions as spinning solvents, the need of employing highly toxic cross-linkers, and the lack of stimuli-responsive functions. In this context, water-soluble N-maleoyl functional chitosan (MCS) was successfully synthesized and well characterized. Using neutral deionized water as a spinning solvent, MCS/PVA nanofibers were prepared via electrospinning under the optimal operating conditions. Instead of using conventional cross-linking methodologies, the MCS/PVA nanofibers were further cross-linked by UV-irradiation with allyl disulfide as a cross-linker. The resulting disulfide cross-linked MCS/PVA (ss-MCS/PVA) nanofibers have demonstrated great water stability, high water regain ability, insignificant cytotoxicity, and reductant-responsive functions. With a successful loading of an antibiotic tetracycline hydrochloride (TCH) and those favorable material features, ss-MCS/PVA nanofibers are capable of being exploited as a potential wound dressing to promote the healing of various types of wounds.

Using the 3(rd) generation Grubbs' catalyst as the initiator, diblock brush polymer drug conjugates (BPDCs) were synthesized by sequential ring-opening metathesis polymerization (ROMP) of a hydrophilic poly(ethylene glycol) (PEG)-based norbornene (NB)-functionalized macromonomer and a hydrophobic paclitaxel (PTXL)-based NB-functionalized monomer. These amphiphilic diblock BPDCs had well-defined structures, with narrow molecular weight distributions (Mw/Mn = 1.10-1.16). They self-assembled into multi-molecular nanostructures in aqueous solutions. Although the PTXL moieties were connected to the backbone with cycloacetal-based conjugation linkages, the cleavage of these linkages from the assemblies of diblock BPDCs was relatively slow and exhibited limited acid-sensitivity, indicating a significant influence of the macromolecular structure and assembly of BPDCs on their drug release behaviour. The cytotoxicity study not only showed that the diblock BPDCs are therapeutically effective against cancer cells, but also revealed a correlation between cytotoxicity and grafting structures of BPDCs. In summary, the results obtained in this work provide new insight into the structure-dependent properties of brush polymer-based drug delivery systems.

To achieve a conjugated drug delivery system with high drug loading but minimal long-term side effects, a degradable brush polymer-drug conjugate (BPDC) was synthesized through azide-alkyne click reaction of acetylene-functionalized polylactide (PLA) with azide-functionalized paclitaxel (PTXL) and poly(ethylene glycol) (PEG). Well-controlled structures of the resulting BPDC and its precursors were verified by (1)H NMR and gel permeation chromatography (GPC) characterizations. With nearly quantitative click efficiency, drug loading amount of the BPDC reached 23.2 wt %. Both dynamic light scattering (DLS) analysis and transmission electron microscopy (TEM) imaging indicated that the BPDC had a nanoscopic size around 10-30 nm. The significant hydrolytic degradability of the PLA backbone of the BPDC was confirmed by GPC analysis of its incubated solution. Drug release study showed that PTXL moieties can be released through the cleavage of the hydrolyzable conjugation linkage in pH 7.4 at 37 °C, with 50% release in about 22 h. As illustrated by cytotoxicity study, while the polymeric scaffold of the BPDC is nontoxic, the BPDC exhibited higher therapeutic efficacy toward MCF-7 cancer cells than free PTXL at 0.1 and 1 μg/mL. Using Nile red as encapsulated fluorescence probe, cell uptake study showed effective internalization of the BPDC into the cells.