Microfluidic Controlled Self-Assembly of Polylactide (PLA)-Based Linear and Graft Copolymers into Nanoparticles with Diverse Morphologies

This study outlines the microfluidic (MF) controlled self-assembly of polylactide (PLA)-based linear and graft copolymers. The PLA-based copolymers (PLA-Cs) were synthesized through a convenient one-pot/one-step ROP/RAFT technique. Three distinct vinyl monomers-triethylene glycol methacrylate (TEGMA), 2-hydroxypropyl methacrylate (HPMA), and N-(2-hydroxypropyl) methacrylamide (HPMAA) were employed to prepare various copolymers: linear thermoresponsive polylactide-b-poly(triethylene glycol methacrylate) (PLA-b-PTEGMA), graft pseudothermoresponsive poly[N-(2-hydroxypropyl)] methacrylate-g-polylactide (PHPMA-g-PLA), and graft amphiphilic poly[N-(2-hydroxypropyl)] methacrylamide-g-polylactide (PHPMAA-g-PLA). The MF technology was utilized for the controlled self-assembly of these PLA-based BCs in a solution, resulting in a range of nanoparticle (NP) morphologies. The thermoresponsive PLA-b-PTEGMA diblock copolymer formed thermodynamically stable micelles (Ms) through kinetically controlled assemblies. Similarly, employing MF channels led to the self-assembly of PHPMA-g-PLA, yielding polymersomes (PSs) with adjustable sizes under the same solution conditions. Conversely, the PHPMAA-g-PLA copolymer generated worm-like particles (Ws). The analysis of resulting nano-objects involves techniques such as transmission electron microscopy, dynamic light scattering investigations (DLS), and small-angle X-ray scattering (SAXS). More specifically, the thermoresponsive behavior of PLA-b-PTEGMA and PHPMA-g-PLA nano-objects is validated through variable-temperature DLS, TEM, and SAXS methods. Furthermore, the study explored the specific interactions between the formed Ms, PSs, and/or Ws with proteins in human blood plasma, utilizing isothermal titration calorimetry.

Thermosensitive Polyhedral Oligomeric Silsesquioxane Hybrid Hydrogel Enhances the Antibacterial Efficiency of Erythromycin in Bacterial Keratitis

Bacterial keratitis is a serious ocular infection that can impair vision or even cause blindness. The clinical use of antibiotics is limited due to their low bioavailability and drug resistance. Hence, there is a need to develop a novel drug delivery system for this infectious disease. In this study, erythromycin (EM) was encapsulated into a bifunctional polyhedral oligomeric silsesquioxane (BPOSS) with the backbone of the poly-PEG/PPG urethane (BPEP) hydrogel with the aim of improving the drug efficiency in treating bacterial keratitis. A comprehensive characterization of the BPEP hydrogel was performed, and its biocompatibility was assessed. Furthermore, we carried out the evaluation of the antimicrobial effect of the BPEP-EM hydrogel in S. aureus keratitis using in vivo mouse model. The BPEP hydrogel exhibited self-assembling and thermogelling properties, which assisted the drug loading of drug EM and improved its water solubility. Furthermore, the BPEP hydrogel could effectively bind with mucin on the ocular surface, thereby markedly prolonging the ocular residence time of EM. In vivo testing confirmed that the BPEP-EM hydrogel exerted a potent therapeutic action in the mouse model of bacterial keratitis. In addition, the hydrogel also exhibited an excellent biocompatibility. Our findings demonstrate that the BPEP-EM hydrogel showed a superior therapeutic effect in bacterial keratitis and demonstrated its potential as an ophthalmic formulation.

Biodegradation of polylactic acid by a mesophilic bacteria Bacillus safensis

A mesophilic bacterial strain, Bacillus safensis PLA1006, was isolated from landfill soil and was tested for growth on polylactic acid (PLA) emulsion medium. The strain formed clear zones on the medium and produced protease and lipase. The macroscopic morphology of the PLA films was not changed significantly after treatment with Bacillus safensis PLA1006 but the films were whitened. Weight loss of PLA films was about 8% after 30 days of incubation with Bacillus safensis PLA1006 in mineral salt medium. Scanning electron microscopy revealed etching on the surface of PLA film treated by Bacillus safensis PLA1006. This also caused an increase in hydrophilicity of the PLA films surface. Attenuated total reflectance - Fourier transform infrared spectroscopy analysis of PLA films after treated by Bacillus safensis PLA1006 showed no new absorption peaks but a decrease in the intensity of all absorption peaks. The hydrolysis products of PLA by the strain contained monomers and oligomers of lactic acid. Zymogram detection showed that proteases may play a role in the degradation of PLA.

Evaluation of Ibuprofen Prolonged Release of Biomedical PLA-PEG-PLA Hydrogel via Degradation Mechanism

A micellar hydrogel has long been considered an intelligent hydrophobic drug delivery material. In this study, synthesized PLA₁₇₅₀-PEG₁₇₅₀-PLA₁₇₅₀ micellar hydrogel aims to encapsulate ibuprofen (IBU) in the core PLA hydrophobic of the micelle and prolong the drug release time by an injectable route. The structure and morphology of the PLA₁₇₅₀-PEG₁₇₅₀-PLA₁₇₅₀ copolymer hydrogel were demonstrated by ¹H NMR and TEM data. The hydrogel also achieved a gel state at a high concentration of 25 wt.% under the physiological conditions of the body (37°C, pH 7.4). Besides, the biocompatibility test displayed that the hydrogel slightly affected mice after injection one week and fully recovered after four weeks. Furthermore, the in vitro degradation of the hydrogel showed apparent gel erosion after the first three weeks, which is related to the IBU release rate: slow for the first three weeks and then fast. As a result, the total drug release after three and four weeks was 18 wt.% and 41 wt.%, respectively. However, in the first 24 hours, the amount of the drug released was 10 wt.%, suggesting that the IBU drug diffused from the surface hydrogel to the buffer solution. These show that PLA₁₇₅₀-PEG₁₇₅₀-PLA₁₇₅₀ hydrogel can be a potential IBU drug delivery candidate.

Injectable PTHF-based thermogelling polyurethane implants for long-term intraocular application

BACKGROUND

Hydrogels show great potential to be used for intraocular applications due to their high-water content and similarity to the native vitreous. Injectable thermosensitive hydrogels through a small-bore needle can be used as a delivery system for drugs or a tamponading substitute to treat posterior eye diseases with clear clinical potential. However, none of the currently available thermosensitive hydrogels can provide intraocular support for up to 3 months or more.

METHOD

In this study, an injectable polytetrahydrofuran (PTHF)-based thermosensitive hydrogel was synthesized by polyurethane reaction. We examined the injectability, rheological properties, microstructure, cytotoxicity, and in vivo compatibility and stability of the hydrogels in rabbit eyes.

RESULTS

We found that the PTHF block type and PTHF component ratio could modulate thermogelation properties of the polyurethane polymers. The PTHF-based hydrogel implants retained normal retinal structure and function. Incorporating bioinert PTHF generated highly biocompatible and more stable thermogels in the vitreous cavity, with gel networks and the presence of polymer still observed after 3 months when other thermogels would have been completely cleared. Moreover, despite lacking hydrolytically cleavable linkages, the polymers could be most naturally removed from the native vitreous by bio-erosion without additional surgical interventions.

CONCLUSION

Our findings suggest the potential of incorporating hydrophobic bioinert blocks to enhance the in vivo stability of supramolecularly associated hydrogels for long-term intraocular applications.

Development of Heavy Metal-Free Photocatalytic RhB Decomposition System Using a Biodegradable Plastic Substrate

The heavy-metal-free photocatalytic system, in which carbon nitride is coated on polylactic acid (PLA) as biodegradable plastic through a simple dip coating method, was used for dye decomposition under visible light irradiation. Solvent selection, solvent concentration, and the number of coatings for dip coating were investigated to optimize the conditions for loading carbon nitride on PLA. Carbon nitride cannot be coated on PLA in water, but it can be strongly coated by decomposing the surface of PLA with ethanol or chlorobenzene to promote physical adsorption and activate surface. The number of dip coatings also affected the photocatalytic decomposition ability. The photocatalytic system was able to decompose the dye continuously in the flow method, and dye (rhodamine B) was decomposed by about 50% at a residence time of 12 min (flow rate 0.350 mL/min) for 30 h.

A Review: Research Progress in Modification of Poly (Lactic Acid) by Lignin and Cellulose

With the depletion of petroleum energy, the possibility of prices of petroleum-based materials increasing, and increased environmental awareness, biodegradable materials as a kind of green alternative have attracted more and more research attention. In this context, poly (lactic acid) has shown a unique combination of properties such as nontoxicity, biodegradability, biocompatibility, and good workability. However, examples of its known drawbacks include poor tensile strength, low elongation at break, poor thermal properties, and low crystallization rate. Lignocellulosic materials such as lignin and cellulose have excellent biodegradability and mechanical properties. Compounding such biomass components with poly (lactic acid) is expected to prepare green composite materials with improved properties of poly (lactic acid). This paper is aimed at summarizing the research progress of modification of poly (lactic acid) with lignin and cellulose made in in recent years, with emphasis on effects of lignin and cellulose on mechanical properties, thermal stability and crystallinity on poly (lactic acid) composite materials. Development of poly (lactic acid) composite materials in this respect is forecasted.

Supramolecular thermogels from branched PCL-containing polyurethanes

Thermogels are temperature-responsive hydrogels which are most commonly formed by supramolecular self-assembly of polymer amphiphiles comprising of both hydrophobic and hydrophilic segments. Although polyurethane thermogels have shown great promise as biomaterials, their synthesis by step-growth polymerisation of diols and diisocyanates can also result in formation of allophanate branches, which arise from the reaction between free isocyanate groups and urethane linkages along the polymer backbone. In this paper, we investigate the effects of different synthetic conditions on the degree of allophanate branching on polyurethane amphiphiles, and explore the influences of these branches on the polymers' critical micelle concentration (CMC), thermodynamics of micellization and subsequent thermogel properties. Our findings offer new insights into the relationship between polymer structure, micelle and gel properties. These results highlight the importance of taking polymer branching into account for understanding the hierarchical self-assembly of polymer amphiphiles and the resulting thermogel properties and behaviour.

Self-Assemblable Polymer Smart-Blocks for Temperature-Induced Injectable Hydrogel in Biomedical Applications

Self-assembled temperature-induced injectable hydrogels fabricated via self-assembly of polymer smart-blocks have been widely investigated as drug delivery systems and platforms for tissue regeneration. Polymer smart-blocks that can be self-assembly play an important role in fabrication of hydrogels because they can self-assemble to induce the gelation of their copolymer in aqueous solution. The self-assembly occurs in response to an external stimulus change, such as temperature, pH, glucose, ionic strength, light, magnetic field, electric field, or their combination, which results in property transformations like hydrophobicity, ionization, and conformational change. The self-assembly smart-block based copolymers exist as a solution in aqueous media at certain conditions that are suitable for mixing with bioactive molecules and/or cells. However, this solution turns into a hydrogel due to the self-assembly of the smart-blocks under exposure to an external stimulus change in vitro or injection into the living body for a controllable release of loaded bioactive molecules or serving as a biomaterial scaffold for tissue regeneration. This work reports current scenery in the development of these self-assembly smart-blocks for fabrication of temperature-induced injectable physically cross-linked hydrogels and their potential application as drug delivery systems and platforms for tissue engineering.

Self-Healable, Fast Responsive Poly(ω-Pentadecalactone) Thermogelling System for Effective Liver Cancer Therapy

A polyurethane based thermogelling system comprising poly(ω-pentadecalactone) (PPDL), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG), termed as PDEP, was synthesized. The incorporation of PPDL lowers critical micelle concentration (CMC) as well as critical gelation concentration (CGC) of the novel copolymers compared to commercial Pluronic® F127. The thermogels showed excellent thermal stability at high temperature up to 80°C, fast response to temperature change in a time frame of less than second, as well as remarkable self-healing properties after being broken at high strain. In vitro drug release studies using docetaxel (DTX) and cell uptake studies using doxorubicin (DOX) show high potential of the hydrogel as drug reservoir for sustainable release profile of payloads, while the in vivo anti-tumor evaluation using mice model of hepatocellular carcinoma further demonstrated the significant inhibition on the growth of tumor. Together with its excellent biocompatibility in different organs, the novel PDPE thermogelling copolymers reported in this work could potentially be utilized as in situ-forming hydrogels for liver cancer therapy.

Polymeric nanoparticles as carrier for targeted and controlled delivery of anticancer agents

In recent decades, many novel methods by using nanoparticles (NPs) have been investigated for diagnosis, drug delivery and treatment of cancer. Accordingly, the potential of NPs as carriers is very significant for the delivery of anticancer drugs, because cancer treatment with NPs has led to the improvement of some of the drug delivery limitations such as low blood circulation time and bioavailability, lack of water solubility, drug adverse effect. In addition, the NPs protect drugs against enzymatic degradation and can lead to the targeted and/or controlled release of the drug. The present review focuses on the potential of NPs that can help the targeted and/or controlled delivery of anticancer agents for cancer therapy.

Sustained delivery of anti-VEGFs from thermogel depots inhibits angiogenesis without the need for multiple injections

Polyurethane thermogels show sustained delivery of bioactive anti-VEGFs therapeutics to the eye.

Chitosan-based liposomal thermogels for the controlled delivery of pingyangmycin: design, optimization and in vitro and in vivo studies

Pingyangmycin (PYM) has been applied clinically for many years to treat vascular malformations (VM) in China. The major limitation of PYM injections is quick diffusion from the injection site, which increases side effects, especially the possibility of pulmonary injury. In this paper, chitosan/glycerophosphate disodium (CS/GP) thermogels containing liposomes for sustained and localized PYM delivery were prepared and optimized by a three-level three-factorial Box–Behnken experimental design to evaluate the effects of different variables (the PYM concentration, CS amount and GP content), on the selected responses (cumulative percentage PYM released in 1 day, 9 days and the rate constant k). The results revealed that the optimized PYM liposomal thermogels had a controlled PYM release for 14 days in vitro, which confirmed the validity of optimization. In vitro morphological observation, cell cycle and apoptosis analysis showed an effective anti-proliferation action of PYM liposomal thermogels on human vascular endothelial cells (EA.hy926). In vivo pharmacokinetics research in rabbits displayed that compared with PYM liposomes and PYM thermogels, PYM liposomal thermogels had a better controlled delivery of PYM. Histological examination of rabbit ear veins showed that after local application with PYM lipsomal thermogels for 21 days, obvious vein thrombosis and inflammatory reaction could be observed. The above results indicated that PYM-loaded lipsomal CS/GP thermogels might have a good prospect for the treatment of VM.

A Recent Perspective on Noncovalently Formed Polymeric Hydrogels

Chemically crosslinked covalent hydrogels form a permanent and often strong network, and have been extensively used so far in drug delivery and tissue engineering. However, it is more difficult to induce dynamic and highly tunable changes in these hydrogels. Noncovalently formed hydrogels show promise as inherently reversible systems with an ability to change in response to dynamic environments, and have garnered strong interest recently. In this Personal Account, we elucidate a few key attractive properties of noncovalent hydrogels and describe recent developments in hydrogels crosslinked using various different noncovalent interactions. These hydrogels offer huge control for modulating material properties and could be more relevant mimics for biological systems.

Thermogelling 3D Systems towards Stem Cell-Based Tissue Regeneration Therapies

Stem cell culturing and differentiation is a very important research direction for tissue engineering. Thermogels are well suited for encapsulating cells because of their non-biotoxic nature and mild sol-gel transition as temperature increases. In particular, thermogels provide a 3D growth environment for stem cell growth, which is more similar to the extracellular matrix than flat substrates, so thermogels as a medium can overcome many of the cell abnormalities caused by 2D cell growth. In this review, we summarize the applications of thermogels in cell and stem cell culture in recent years. We also elaborate on the methods to induce stem cell differentiation by using thermogel-based 3D scaffolds. In particular, thermogels, encapsulating specific differentiation-inducing factor and having specific structures and moduli, can induce the differentiation into the desired tissue cells. Three dimensional thermogel scaffolds that control the growth and differentiation of cells will undoubtedly have a bright future in regenerative medicine.

Synergistic Lysosomal Activatable Polymeric Nanoprobe Encapsulating pH Sensitive Imidazole Derivative for Tumor Diagnosis

Developing optical tumor imaging probes with minimal background noise is very important for its early detection of small lesions and accurate diagnosis of cancer. To overcome the bottleneck of low signal to noise ratio and sensitivity, it needs further improvement in fluorescent probe design and understanding of tumor development process. Recent reports reveal that lysosome's acidity in cancer cells can be below 4.5 with high Na⁺ /H⁺ exchange activity, which makes it an ideal target intracellular organelle for cancer diagnosis based on the variation of pH. Herein, a boron 2-(2'-pyridyl) imidazole complex derivative (BOPIM-N) is developed, with the ability to show a pH-activatable "OFF-ON" fluorescent switch by inhibiting twisted intramolecular charge transfer upon protonation at pH 3.8-4.5, which is studied for its selective viable cancer cell imaging ability in both in vitro and in vivo experiments. Interestingly, BOPIM-N can specifically emit green fluorescence in lysosomes of cancer cells, indicating its promising cancer cell specific imaging ability. More importantly, nanoformulated BOPIM-N probes can be specifically light-ON in tumor bearing site of nude mice with resolution up to cellular level, indicating its potential application in tumor diagnosis and precision medicine.

Hierarchically Self-Assembled Supramolecular Host-Guest Delivery System for Drug Resistant Cancer Therapy

In this report, a new star-like copolymer β-CD- g-(PNIPAAm- b-POEGA) _x, consisting of a β-CD core, grafted with temperature-responsive poly( N-isopropylacrylamide) (PNIPAAm) and biocompatible poly(oligo(ethylene glycol) acrylate) (POEGA) in a block copolymer of the arms, was used to deliver chemotherapeutics to drug resistant cancer cells and tumors. The first step of the self-assembly process involves the encapsulation of chemotherapeutics through host-guest inclusion complexation between the β-cyclodextrin cavity and the anticancer drug. Next, the chain interaction of the PNIPAAm segment at elevated temperature drives the drug-loaded β-CD- g-(PNIPAAm- b-POEGA) _x/PTX inclusion complex to hierarchically self-assemble into nanosized supramolecular assemblies at 37 °C, whereas the presence of poly(ethylene glycol) (PEG) chains in the distal end of the star-like copolymer arms impart enhanced stability to the self-assembled structure. More interestingly, this supramolecular host-guest nanocomplex promoted the enhanced cellular uptake of chemotherapeutics in MDR-1 up-regulated drug resistant cancer cells and exhibited high therapeutic efficacy for suppressing drug resistant tumor growth in an in vivo mouse model, due to the increased stability, improvement in aqueous solubility, enhanced cellular uptake, and partial membrane pump impairment by taking the advantage of PEGylation and supramolecular complex between this star-like copolymer and chemotherapeutics. This work signifies that temperature-sensitive PEGylated supramolecular nanocarriers with good biocompatibility are effective in combating MDR-1 mediated drug resistance in both in vitro and in vivo models, which is of significant importance for the advanced drug delivery platform designed to combat drug resistant cancer.

Poly(carbonate urethane)-Based Thermogels with Enhanced Drug Release Efficacy for Chemotherapeutic Applications

In this study, we report the synthesis and characterisation of a thermogelling poly(carbonate urethane) system comprising poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG) and poly(polytetrahydrofuran carbonate) (PTHF carbonate). The incorporation of PTHF carbonate allowed for the control of the lower critical solution temperature (LCST) and decreased critical gelation concentration (CGC) of the thermogels significantly. In addition, the as-prepared thermogels displayed low toxicity against HepG2, L02 and HEK293T cells. Drug release studies were carried out using doxorubicin (Dox). Studies conducted using nude mice models with hepatocellular carcinoma revealed that the Dox-loaded poly(PEG/PPG/PTHF carbonate urethane) thermogels showed excellent in vivo anti-tumour performance and effectively inhibited tumour growth in the tested model.

Biocompatible and mechanically robust nanocomposite hydrogels for potential applications in tissue engineering

The synergistic contributions of nanofillers and polymer matrix induce remarkable properties in nanocomposite hydrogels. Present article reports the facile synthesis of biocompatible nanocomposite hydrogels using microporous multi wall carbon nanotubes (MWCNTs) dispersed chitosan (CH)-Acrylonitrile (AN), N,N'-methylenebisacrylamide (MBAAm) and linseed polyol through solution blending method. Polyol and N,N'-methylenebisacrylamide (MBAAm) was used as the crosslinking agent. The structural characterization and formation of highly crosslinked network with dendrimer morphology was confirmed by FT-IR and scanning electron microscope (SEM) analysis. In addition, transmission electron microscope (TEM) was employed to visualize the size and proper dispersion of MWCNT in the polymer matrices. The strong mechanical strength exhibited by these hydrogel films was confirmed by the tensile strength analysis. The dispersion of the conductive nanofillers, like MWCNTs has significantly enhanced the strength, which revealed unique characteristics of these hydrogel films. The high swelling capacity and sustained expansion of hydrogel films were confirmed in the buffer solutions of pH4 and 7.4. The biodegradability of these films was estimated by hydrolytic and soil burial tests. The biocompatibility test was conducted on Human Embryonic Kidney (HEK-293) cell line, which confirmed the non-toxic and biocompatible nature of these films. Incorporation of carbon nanotubes (MWCNTs) in the polymer matrix enhanced the film forming properties, high modulus and tensile strength, swelling ability, biodegradable and biocompatibility. These properties can be finely tuned through the variation of MWCNT concentrations, as a result these nanostructure hydrogel films have potential scope for their diverse applications in the field of tissue engineering.

Multi-responsive hydrogels with UCST- and LCST-induced shrinking and controlled release behaviors of rhodamine B

By using a disulfide-functionalized crosslinker, a pH- and thermo-responsive 2-(dimethylamino) ethyl methacrylate (DMAEMA) monomer and a zwitterionic sulfobetaine methacrylate (SBMA) monomer were conjugated to fabricate a multi-responsive P(DMAEMA-SS-SBMA) copolymeric hydrogel. Apparent UCST and LCST volume transitions were observed in the P(DMAEMA-SS-SBMA) hydrogels with equivalent weight fractions of monomers. Different pore size and response sensitivity of shrunken structures below UCST and above LCST were visualized by SEM images. The hydrogel exhibited a highly swollen state with a swelling ratio of 17.8 and a pore size of 106μm at 45°C, they deswelled unequally at 5°C with a compact surface with pore size of 30μm and a loose bulk with pore size of 83μm, while they deswelled uniformly at 65°C with dense shrunken structure with small pore size of 12μm. The dual-thermoresponsive hydrogel was promising in controlled drug release. The initial drug release was predominantly controlled by diffusion, and the long-term release was influenced by the swelling ratio. Below UCST, the relatively hydrophilic shrunken structure and slow diffusion had a synergistic effect on the sustained release. Above LCST, the fast diffusion and the rapid "off" effect of hydrophobic skin layer resulted in a burst release. Additionally, pH-tunable swelling and redox-sensitive degradation were also observed.

Overcoming STC2 mediated drug resistance through drug and gene co-delivery by PHB-PDMAEMA cationic polyester in liver cancer cells

Stanniocalcin 2 (STC2) overexpression in hepatocellular carcinoma (HCC) could lead to poor prognosis, which might be due to its induced P-glycoprotein and Bcl-2 protein expression level increase. P-glycoprotein or membrane pump induced drug efflux and altered prosurvival Bcl-2 expression are key mechanisms for drug resistance leading to failure of chemotherapy in HCC. However, current strategy to overcome both P-glycoprotein and Bcl-2 protein induced drug resistance was rarely reported. In this work, we utilized an amphiphilic poly[(R)-3-hydroxybutyrate] (PHB)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) cationic polyester to encapsulate chemotherapeutic paclitaxel (PTX) in hydrophobic PHB domain and Bcl-2 convertor Nur77/ΔDBD gene (Nur77 without DNA binding domain for mitochondria localization) by formation of polyplex due to cationic PDMAEMA segment, to effectively inhibit the drug resistant HepG2/STC2 and SMCC7721/STC2 liver cancer cell growth. Thanks to the cationic nanoparticle complex formation ability and high transfection efficiency to express Bcl-2 conversion proteins, PHB-PDMAEMA/PTX@polyplex could partially impair P-glycoprotein induced PTX efflux and activate the apoptotic function of previous prosurvival Bcl-2 protein. This is the pioneer report of cationic amphiphilic polyester PHB-PDMAEMA to codeliver anticancer drug and therapeutic plasmid to overcome both pump and non-pump mediated chemotherapeutic resistance in liver cancer cells, which might be inspiring for the application of polyester in personalized cancer therapy.

Injectable Supramolecular Hydrogels as Delivery Agents of Bcl-2 Conversion Gene for the Effective Shrinkage of Therapeutic Resistance Tumors

Injectable hydrogels to deliver therapeutic genes in a minimally invasive manner and to achieve long term sustained release at tumor sites to minimize side effects are attractive for cancer therapy and precision medicine, but its rational design remains a challenge. In this report, an injectable supramolecular hydrogel system is designed based on the polypesudorotaxane formation between α-cyclodextrin (α-CD) and cationic methoxy-poly(ethylene glycol)-b-poly(ε-caprolactone)-b-poly(ethylene imine) (MPEG-PCL-PEI) copolymer, with the ability to form polyplexes with anionic plasmid DNA for effective sustained gene delivery. To be mentioned, the MPEG-PCL-PEI copolymers show similar pDNA binding ability, better gene transfection efficiency, lower cytotoxicity than nonviral gene transfection gold standard PEI (25 kDa), due to the formation of micelles and more stable polyplexes. More importantly, this MPEG-PCL-PEI/α-CD/pDNA supramolecular hydrogel shows a sustained release of pDNA in form of polyplex for up to 7 d. By taking these advantages, this supramolecular hydrogel system is applied as an injectable carrier for sustained Bcl-2 conversion gene release, in an in vivo rodent model of therapeutic resistant hepatocarcinoma with high expression of antiapoptotic Bcl-2 protein. This work represents the first time that injectable MPEG-PCL-PEI/α-CD supramolecular hydrogels possess good controllable release effect of Bcl-2 conversion genes in the form of polyplex to effectively inhibit in vivo tumor growth and this "enemy to friend" strategy will benefit various applications, including on-demand gene delivery and personalized medicine.

Review of Adaptive Programmable Materials and Their Bioapplications

Adaptive programmable materials have attracted increasing attention due to their high functionality, autonomous behavior, encapsulation, and site-specific confinement capabilities in various applications. Compared to conventional materials, adaptive programmable materials possess unique single-material architecture that can maintain, respond, and change their shapes and dimensions when they are subjected to surrounding environment changes, such as alternation in temperature, pH, and ionic strength. In this review, the most-recent advances in the design strategies of adaptive programmable materials are presented with respect to different types of architectural polymers, including stimuli-responsive polymers and shape-memory polymers. The diverse functions of these sophisticated materials and their significance in therapeutic agent delivery systems are also summarized in this review. Finally, the challenges for facile fabrication of these materials and future prospective are also discussed.

Supramolecular cyclodextrin nanocarriers for chemo- and gene therapy towards the effective treatment of drug resistant cancers

A tumor active targeting β-cyclodextrin based nanocarrier β-NC-OEI-SS-FA was designed by the modification of star shaped cationic derivatives β-NC-OEI with folic acid through a disulfide bond, to co-deliver chemotherapeutic paclitaxel and the Nur77 gene for overcoming Bcl-2 mediated non-pump resistance by an "enemy to friend" strategy for potential drug resistant cancer therapy.

PHB-Based Gels as Delivery Agents of Chemotherapeutics for the Effective Shrinkage of Tumors

Injectable thermogel to deliver chemotherapeutics in a minimally invasive manner and to achieve their long term sustained release at tumor sites to minimize side effects is attractive for chemotherapy and precision medicine, but its rational design remains a challenge. In this work, a copolymer with natural biodegradable poly[(R)-3-hydroxybutyrate] (PHB), hydrophilic poly(ethylene glycol), and temperature sensitive poly(propylene glycol) blocks linked by urethane linkages is designed to show thermogelling characteristics which are beneficial for minimally invasive injection and safe degradation. This thermogelling polymer possesses in vitro biocompatibility with very low cyto-toxicity in HEK293 cells. Furthermore, it is able to form the gel to achieve the controllable release of paclitaxel (PTX) and doxorubicin (DOX) by adjusting polymer concentrations. A rodent model of hepatocarcinoma has been performed to demonstrate the in vivo applications of this PHB-based thermogel. The drug-loaded thermogel has been intratumorally injected and both PTX-loaded and DOX-loaded thermogel have significantly slowed down tumor growth. This work represents the first time that injectable PHB thermogels have possessed good controllable release effect of chemotherapeutics against the in vivo model of tumors and will benefit various applications, including on-demand drug delivery and personalized medicine.

Modification of Thermal and Mechanical Properties of PEG-PPG-PEG Copolymer (F127) with MA-POSS

Pluronic F127 exhibits thermogelling behaviour at 20⁻30 °C via a micelle packing mechanism. Disruption of the micelle packing increases the sol-gel temperature, but results in the decrease of modulus. Herein, we reported a method to modify F127 with polyhedral oligosilsesquioxane (POSS) to impart a higher gelling temperature without yielding the property and strength of the thermogel. The thermal degradation temperature was enhanced to 15 °C after POSS incorporation and the gelling temperature shifted 10 °C higher, without sacrificing the modulus of the gel. Rheological studies supported the claim that the gel property was reinforced after POSS incorporation. F127-POSS copolymer matrix stored more energy from POSS reinforcement, which saw larger Lissajous curve areas before the collapse of the microstructure for the same amount of stress applied. These results indicated that modification with POSS would raise the sol-gel transition temperature without sacrificing the modulus of the gel.

A Smart pH-Responsive Three Components Luminescent Hydrogel

In this study, we report a novel three-component luminescent hydrogel, which is composed of amino acid derivatives (N,N'-di valine-3,4,9,10-perylenetetracarboxylic acid, NVPD), riboflavin (RF), and melamine (MM). The three-component hydrogel is attributed to multiple hydrogen bonds and the strong π-π stacking interaction between these molecules. Based on the strong hydrogen bonding of the gelator, when the reversible process between the gel and the solution take places it changes the pH of the system from 6.1 to 10.6. In addition, green fluorescence could be the emissive of the hydrogel under 498 nm and the conversion process of the aggregation state repeated reversibly by altering the value of ambient pH. This pH-responsive luminescent gel may display potential for use in nano pH sensors.

Nanomaterial mediated optogenetics: opportunities and challenges

This review elaborates on the possible applications of nanomaterials in optogenetics and analyses the benefits of nanomaterial-mediated optogenetics.

Small molecule therapeutic-loaded liposomes as therapeutic carriers: from development to clinical applications

In this review, various methods and mechanisms for encapsulation of small therapeutic molecules in liposomes for targeted delivery and triggered release, as well as their potential in the clinical uses, are discussed.

Functional biomedical hydrogels for in vivo imaging

In vivo imaging of biomedical hydrogels enables real-time and non-invasive visualization of the status of structure and function of hydrogels.