ICAR ATRP Polymerization-Induced Self-Assembly Using a Mixture of Macroinitiator/Stabilizer with Different Molecular Weights.

The poly[oligo(ethylene oxide) methyl ether methacrylate]s, POEOMA24 and POEOMA78 with average degree of polymerization (DP) of 24 and 78, respectively, are separately achieved by initiators for continuous activator regeneration (ICAR) atom transfer radical polymerization (ATRP) of OEOMA300 monomer. The mixtures of [POEOMA24 ]0 /[POEOMA78 ]0 = 1/1, 2/1, or 4/1 are employed as macroinitiator/stabilizer to practice the ICAR ATRP polymerization-induced self-assembly (PISA) of benzyl methacrylate (BnMA) at 65 °C. When the obtained dispersions are sequentially cooled to room temperature, diluted into ethanol, and observed by transmission electron microscopy (TEM) measurement, the cases of [POEOMA24 ]0 /[POEOMA78 ]0 = 1/1 or 2/1 and target DPPB n MA = 100 or 200 lead to nanoparticles with irregular sizes, while the cases of [POEOMA24 ]0 /[POEOMA78 ]0 = 4/1 and target DPPB n MA = 300 give the regular ones. When the obtained dispersions at a high temperature (65 °C) are directly diluted into room temperature ethanol and observed by TEM, nanoparticles with light contrast but clear contour can be observed. The results show that the higher content of POEOMA78 tends to improve the solubility of diblock copolymer and thus leads to insufficient stabilization of the nanoparticles. The morphological difference from the room-temperature and 65 °C dispersions help elucidate the intrinsic character of the PISA system.

Polymeric Janus Nanoparticles: Recent Advances in Synthetic Strategies, Materials Properties, and Applications.

Polymeric Janus nanoparticles with two sides of incompatible chemistry have received increasing attention due to their tunable asymmetric structure and unique material characteristics. Recently, with the rapid progress in controlled polymerization combined with novel fabrication techniques, a large array of functional polymeric Janus particles are diversified with sophisticated architecture and applications. In this review, the most recently developed strategies for controlled synthesis of polymeric Janus nanoparticles with well-defined size and complex superstructures are summarized. In addition, the pros and cons of each approach in mediating the anisotropic shapes of polymeric Janus particles as well as their asymmetric spatial distribution of chemical compositions and functionalities are discussed and compared. Finally, these newly developed structural nanoparticles with specific shapes and surface functions orientated applications in different domains are also discussed, followed by the perspectives and challenges faced in the further advancement of polymeric Janus nanoparticles as high performance materials.

Overcome the Conflict between Strength and Toughness in Poly(lactide) Nanocomposites through Tailoring Matrix-Filler Interface.

Strength and toughness are the two most important prerequisites for structural applications. Unfortunately, these two properties are often in conflict in materials. Here, an effective and yet practical strategy is proposed to simultaneously strengthen and toughen poly(l-lactide) (PLLA) using a simple rigid-rubber "reinforcing element." This element consists of a rigid graphene oxide (GO) sheet covalently coupled with poly(caprolactone-co-lactide) (PCLLA) rubbery layers, which can be easily synthesized and incorporated into PLLA matrix to develop composites with well-tailored GO/PLLA interfaces. It is demonstrated that by adding the "reinforcing element," i.e., GO-graft-rubber-graft-polyd-lactide), PLLA exhibits higher strength and higher toughness, which could be attributed to the synergy of rigid GO and rubbery PCLLA working in tandem during deformation. It is further demonstrated that this strategy can also be applied to other filler systems, such as clay and particulate polyhedral oligomeric silsesquioxane, and other polymer systems, such as poly(methyl methacrylate). The strategy could be considered as a general design principle for reinforcing materials where both strength and toughness are the key concerns.

Precise Synthesis of PS-PLA Janus Star-Like Copolymer.

In this work, an efficient strategy is designed for the precise synthesis of novel Janus star-like copolymer (polystyrene)8 -b-(poly(l-lactide))8 , (PLLA)8 -b-(PS)8 , consisting of two types of chemically distinct polymer arms, PS and PLLA, in an asymmetric structure. During the synthesis, PLLA hemisphere carrying protected hydroxyl groups at the focal point was first synthesized via a combined reactions of esterification, light-induced "Click" chemistry, and ring opening polymerization (ROP) using a specially designed dendron as initiator. After removing the protecting moiety, the terminal hydroxyl groups on the dendron segment is increased fourfold and further modified into bromopropionate-based macroinitiator through a two-step end group transformation reaction, followed by atom transfer radical polymerization (ATRP) of styrene to obtain the desired (PLLA)8 -b-(PS)8 Janus star-like copolymer. The versatility and efficiency of the designed synthetic strategy are demonstrated by the well-defined molecular characteristics and high yields of the targeted product. In addition to the controlled degradation behavior of the PLLA segments, the remaining bromide groups located at the distal end of PS arms could allow for further fabrication of diverse building blocks through consecutive ATRP of various monomers. This work signifies the first time for facile and precise synthesis of Janus star-like copolymer with unique biphasic structure and function control.

Cyclodextrin-Based Star-Like Amphiphilic Cationic Polymer as a Potential Pharmaceutical Carrier in Macrophages.

Effective delivery of therapeutic genes or small molecular drugs into macrophages is important for cell based immune therapy, but it remains a challenge due to the intracellular reactive oxygen species and endosomal degradation of therapeutics inside immune cells. In this report, the star-like amphiphilic biocompatible ß-cyclodextrin-graft-(poly(ε-caprolactone)-block-poly(2-(dimethylamino) ethyl methacrylate)x (ß-CD-g-(PCL-b-PDMAEMA)x ) copolymer, consisting of a biocompatible cyclodextrin core, hydrophobic poly(ε-caprolactone) PCL segments and hydrophilic PDMAEMA blocks with positive charge, is optimized to achieve high efficiency gene transfection with enhanced stability, due to the micelle formation by hydrophobic PCL segments. In comparison with lipofetamine, a currently popular nonviral gene carrier, ß-CD-g-(PCL-b-PDMAEMA)x copolymer, shows better transfection efficiency of plasmid desoxyribose nucleic acid in RAW264.7 macrophages. More interestingly, this delivery platform by ß-CD-g-(PCL-b-PDMAEMA)x not only shows low toxicity but also better dexamethasone delivery efficiency, which might indicate its great potential in immunotherapy.

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

In this report, a new star-like copolymer ß-CD- g-(PNIPAAm- b-POEGA) x, consisting of a ß-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 ß-cyclodextrin cavity and the anticancer drug. Next, the chain interaction of the PNIPAAm segment at elevated temperature drives the drug-loaded ß-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(ethylene glycol) conjugated poly(lactide)-based polyelectrolytes: synthesis and formation of stable self-assemblies induced by stereocomplexation.

A series of pH-responsive amphiphilic poly(N,N-dimethylaminoethyl methacrylate)-block-poly(D-lactic acid)-block-poly(N,N-dimethylaminoethyl methacrylate) conjugated with poly(ethylene glycol) (D-PDLA-D@PEG) and D-PLLA-D@PEG copolymers were synthesized using a combination of ring-opening polymerization and atom-transfer radical polymerization followed by sequential quaternization of PDMAEMA chains and azide-alkyne click reaction with alkyne-end PEG. Gel permeation chromatography, nuclear magnetic resonance, and Fourier transform infrared spectroscopy results demonstrate the successful synthesis of the copolymers, and the conjugated PEG percentages in the copolymers can be tuned by the feeding ratios in the quaternization reaction. Conjugating PEG onto the PDMAEMA segments also successfully facilitated the D-PDLA-D@PEG, D-PLLA-D@PEG, and its corresponding 1:1 D/L mixtures to be dissolved directly in aqueous solution at the desired concentration range without using any organic solvents unlike the copolymers without PEG conjugation (D-PDLA-D and D-PLLA-D). We demonstrate control over micellar size, charge, and stability via three different preparation pathways, i.e., solution pH, percentages of PEG conjugation in the copolymers, and formation of PLA stereocomplex in micellar core. Static and dynamic light scattering studies demonstrate that the size of the core-shell micelles increases when the solution pH is reduced due to the protonation of the PDMAEMA segments that caused the osmotic pressure within the micelle to increase until the micelles reached a maximum size. It is interesting to note that the micelles formed by 1:1 D/L mixtures have larger swelling ratios as well as aggregation number and hydrodynamic radius that do not change significantly with pH and dilution, respectively, as compared to micelles formed from individual D or L forms of the copolymers. The enhanced stability of the pH-responsive micelles prepared by direct dissolution of the 1:1 D/L mixtures of the PEG conjugated PLA-based polyelectrolytes in aqueous medium is attributed to the stereocomplex formation between PLLA and PDLA in the micellar core as confirmed by wide-angle X-ray scattering measurements.

Amphiphilic conetworks and gels physically cross-linked via stereocomplexation of polylactide.

Amphiphilic conetworks (APCNs), consisting of hydrophilic poly[poly(ethylene glycol) methyl ester acrylate] (PPEGMEA) and hydrophobic stereocomplex of poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA), were prepared by free radical copolymerization of PEGMEA with acrylate macromonomer of the PLA stereocomplex. The effects of stereocomplexation and the amount of PLA stereocomplex on the rheology properties of APCNs were investigated. The results indicated that the APCNs was stronger in the presence of stereocomplexation compared with the that of nonstereocomplex system, and the strength of the APCNs increased with the increasing of the amount of PLA stereocomplex. The storage modulus of the APCNs could be easily tuned from 1200 to 4300 Pa by incorporating 2-10% of stereocomplex PLA. On the other hand, the swelling behavior of APCNs decreased with the increasing content of hydrophobic PLA cross-linker.

Polymer nanocomposite hydrogels exhibiting both dynamic restructuring and unusual adhesive properties.

Polymer nanocomposite (NC) hydrogels exhibiting both dynamic restructuring and unusual adhesive properties in wet and dry states have been prepared in an efficient and straightforward way via free radical polymerization of poly(ethylene glycol) methyl ether acrylate (PEG) in the presence of silane-modified sodium montmorillonite (NaMMT). The dynamic restructuring of the NC gel has been demonstrated by almost instant recovery of mechanical properties, such as storage modulus, loss modulus, and damping tan δ (at 0.025 strain) by 60-110% after being stressed to the point of gel failure. Furthermore, the dry NC gel showed exceptional thermal and mechanical stability during a heating and cooling cycle between 25 and 110 °C, with only slightly decreases followed by at least 30% increases in both moduli, while tan δ remained nearly unchanged. The NC gel in dry state could repeatedly adhere to various surfaces such as steel, glass, plastic, etc., and detach from the surface without being broken and leaving little contamination behind. This unique adhesive characteristic was characterized by high storage modulus, loss modulus (kPa), and tan δ (>0.6) corresponding to high cohesive, adhesive, and tacking properties of pressure-sensitive adhesives (PSAs). Finally, a reversible network structure formed by PEO interpenetrating within 3-dimentional (3-D) silica network was proposed to be responsible for the dynamic restructuring and the unique adhesive behaviors observed in the NC gel, and the 3-D network structure was investigated by XRD, FTIR, and DSC measurements. For this 3-D network structure, we suggest that the flexibility of PEO could allow PEO side chains to contact with various surfaces by either PEO segments or methoxy end groups via weak physical interactions, such as van der Waals interactions or hydrogen bonding, whereas the reversible network structure contributes to the recovery of strength and shape after the gel failure.

Stretchable, Environment-Stable, and Knittable Ionic Conducting Fibers Based on Metallogels for Wearable Wide-Range and Durable Strain Sensors.

The construction of fibrous ionic conductors and sensors with large stretchability, low-temperature tolerance, and environmental stability is highly desired for practical wearable devices yet is challenging. Herein, metallogels (MOGs) with a rapidly reversible force-stimulated sol-gel transition were employed and encapsulated into a hollow thermoplastic elastomer (TPE) microfiber through a simple coaxial spinning. The resultant MOG@TPE coaxial fiber exhibited a high stretchability (>100%) in a broad temperature range (-50 to 50 °C). The MOG@TPE fibrous strain sensor demonstrated a high-yet-linear working curve, fast response time (<100 ms), highly stable conductivity under large deformation, and excellent cycling stability (>3000 cycles). The MOG@TPE fibrous sensors were demonstrated to be directly attached to the human skin to monitor the real-time movements of large/facet joints of the elbow, wrist, finger, and knee. It is believed that the present work for preparing the stretchable ionic conductive fibers holds great promise for applications in fibrous wearable sensors with broad temperature range, large stretchability, stable conductivity, and high wearing comfort.

Dual Tumor Microenvironment Remodeling by Glucose-Contained Radical Copolymer for MRI-Guided Photoimmunotherapy.

Aberrant glucose metabolism and immune evasion are recognized as two hallmarks of cancer, which contribute to poor treatment efficiency and tumor progression. Herein, a novel material system consisting of a glucose and TEMPO (2,2,6,6-tetramethylpiperidin-1-yl)oxyl) at the distal ends of PEO-b-PLLA block copolymer (glucose-PEO-b-PLLA-TEMPO), is designed to encapsulate clinical therapeutics CUDC101 and photosensitizer IR780. The specific core-shell rod structure formed by the designed copolymer renders TEMPO radicals excellent stability against reduction-induced magnetic resonance imaging (MRI) silence. Tumor-targeting moiety endowed by glucose provides the radical copolymer outstanding multimodal imaging capabilities, including MRI, photoacoustic imaging, and fluorescence imaging. Efficient delivery of CUDC101 and IR780 is achieved to synergize the antitumor immune activation through IR780-mediated photodynamic therapy (PDT) and CUDC101-triggered CD47 inhibition, showing M1 phenotype polarization of tumor-associated macrophages (TAMs). More intriguingly, this study demonstrates PDT-stimulated p53 can also re-educate TAMs, providing a combined strategy of using dual tumor microenvironment remodeling to achieve the synergistic effect in the transition from cold immunosuppressive to hot immunoresponsive tumor microenvironment.

Synthesis of eight-shaped poly(ethylene oxide) by the combination of Glaser coupling with ring-opening polymerization.

The eight-shaped poly(ethylene oxide) (PEO) is synthesized by a combination of Glaser coupling with ring-opening polymerization (ROP). Firstly, the star-shaped (PEO-OH)(4) is synthesized by ROP of ethylene oxide (EO) using pentaerythritol as an initiator and diphenylmethyl potassium (DPMK) as a deprotonated agent, and then the alkyne group is introduced onto the PEO arm-end to give (PEO-Alkyne)(4) in a NaH/tetrahydrofuran (THF) system. The intramolecular cyclization is carried out by a Glaser coupling reaction in a pyridine/CuBr/N,N,N',N",N"-pentamethyldiethylenetriamine (PMDETA) system at room temperature in an air atmosphere, and eight-shaped PEO was formed with high efficiency (almost 100%). The target polymers and intermediates were well characterized by SEC, MALDI-TOF MS, (1)H NMR and FT-IR in detail.

AuNPs Decorated PLA Stereocomplex Micelles for Synergetic Photothermal and Chemotherapy.

A unique platform for combined photothermal and chemotherapy using PLA stereocomplex (PLA SC) micelles-induced hybrid gold nanocarriers is designed. The PLA SC micelles, made from the self-assembly of poly(ethylene glycol)-block-poly(l-lactide) (PEG-PLLA) and poly(2-(dimethylamino) ethyl methacrylate)-block-poly(d-lactide) (PDMAEMA-PDLA), for the first time are used as a template to fabricate the hybrid PLA SC@Au core-shell nanocarriers, in which the anticancer drugs are encapsulated within the core, while the Au nanoparticles are tethered in the shell via the in situ reduction of AuCl4- by PDMAEMA. The obtained PLA SC@Au hybrid nanocarriers exhibit low toxicity and remarkable photothermal effect. Upon near-infrared laser irradiation, the on-site photothermal therapy can further induce an accelerated drug release from the hybrid nanocarrier reservoir via hyperthermia heating of the nanocarriers, thus leading to a synergistic photothermal and chemotherapy toward a significantly improved efficacy in tumor shrinkage. The as-designed PLA SC@Au hybrid nanocarriers, with their biocompatible compositions, dual-drug delivery characteristics, and combined photothermal/chemotherapy, show high potential as a novel platform for cancer treatment.

Preparation of mixed micelles carrying folates and stable radicals through PLA stereocomplexation for drug delivery.

Multifunctional mixed micelles possessing targeting folates on the periphery and stable radicals in the core were prepared from the mixture of folate-poly(ethylene glycol)-block-poly(d-lactide) (FA-PEG-b-PDLA) and poly(ethylene glycol) methyl ether-block-poly(l-lactide)- 2,2,6,6-tetramethylpiperidine-1-oxyl (mPEG-b-PLLA-TEMPO). FA-PEG-b-PDLA and mPEG-b-PLLA-TEMPO were prepared by combining ring-opening polymerization (ROP) of lactide with a series of conversion of the end functional groups. The synthesized block copolymers and their intermediates were well characterized by gel permeation chromatography (GPC) and 1H nuclear magnetic resonance (1H NMR) spectroscopy. The mixture of FA-PEG-b-PDLA and mPEG-b-PLLA-TEMPO self-assembled into spherical micelles with the average diameter about 200 nm through PLA stereocomplexation, which were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The formed micelles were confirmed to emit electron paramagnetic resonance (EPR) signals by EPR spectroscopy. Additionally, the formed micelles exhibited high loading capacity of hydrophobic anticancer drug, controlled in vitro drug release, satisfied biocompatibility and a significantly higher cellular uptake, indicating promising applications in smart drug delivery.

Reduction-responsive shell cross-linked micelles derived from amphiphilic triblock copolymer as anticancer drug delivery carrier.

Stimuli-responsive crosslinked micelles are attractive carriers for in vivo delivery of water-insoluble therapeutic drugs due to their excellent stability during the blood circulation and high therapeutic effect resulting from the intelligent break-up of the crosslinked structure triggered by intracellular conditions as well as the subsequent fast drug release. Herein, novel amphiphilic triblock copolymer poly(l-lactide)-b-poly(allyl glycidyl ether/propanedithiol)-b-poly(ethylene glycol) (PLLA-b-P(AGE-SH)-b-PEG) was designed and synthesized by combining two successive ring-opening polymerizations and subsequent "thio-ene" reaction. Due to their unique amphiphilic architecture, copolymer PLLA-b-P(AGE-SH)-b-PEG could self-assemble into core-shell micelles, and the stimuli-responsive crosslinked micelles (SCMs) were obtained by crosslinking the P(AGE-SH) segments in the micellar shell under redox condition. The SCMs exhibited good stability against extensive dilution and slow sustained drug release in a simulated normal physiologycal environment, but fast release in the presence of GSH. As revealed by the cytotoxicity assay, the micelles from the copolymer PLLA-b-P(AGE-SH)-b-PEG showed excellent biocompatibility against HEK293T cells. Due to these combined good properties, the stimuli-responsive crosslinked micelles from PLLA-b-P(AGE-SH)-b-PEG are proposed to be an ideal carrier for the in vivo delivery of water-insoluble therapeutics.

Stereocomplexed micelle formation through enantiomeric PLA-based Y-shaped copolymer for targeted drug delivery.

In this study, a novel stereocomplexed micelle system was prepared from the self-assembly of enantiomeric PLA-based Y-shaped copolymers, i.e. folic acid-adamantane/ß-cyclodextrin-b-[poly(D-lactide)]2 (FA-AD/CD-b-(PDLA)2) and poly(2-dimethylaminoethyl methacrylate)-b-[poly(L-lactide)]2 (PDMAEMA-b-(PLLA)2) in aqueous solution. The newly designed Y-shaped copolymer FA-AD/CD-b-(PDLA)2 was prepared by a combination of "click" reaction and host guest interaction between FA-AD and CD-b-(PDLA)2. In addition, enantiomeric Y-shaped PDMAEMA-b-(PLLA)2 copolymer was synthesized through ring-opening polymerization (ROP) of L-lactide using three-head initiator with bromo and -OH at distal ends, followed by atom transfer radical polymerization (ATRP) of DMAEMA to obtain the desired macromolecular architecture. The resultant copolymers and their intermediates were characterized by 1H nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC) techniques. Due to the strong stereocomplexation interaction, FA-AD/CD-b-(PDLA)2 and PDMAEMA-b-(PLLA)2 mixture could self-assemble into stable mixed micelles in aqueous solution. Further, the stereocomplexed micelles exhibited excellent biocompatibility as revealed in the cytotoxicity assay. Together with the intrinsic biodegradability of PLA, it is envisioned that the stereocomplexed micelles developed in this study can be used as a promising nanocarrier for targeting drug delivery.

Thermoresponsive Supramolecular Chemotherapy by "V"-Shaped Armed ß-Cyclodextrin Star Polymer to Overcome Drug Resistance.

Pump mediated drug efflux is the key reason to result in the failure of chemotherapy. Herein, a novel star polymer ß-CD-v-(PEG-ß-PNIPAAm)7 consisting of a ß-CD core, grafted with thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm) and biocompatible poly(ethylene glycol) (PEG) in the multiple "V"-shaped arms is designed and further fabricated into supramolecular nanocarriers for drug resistant cancer therapy. The star polymer could encapsulate chemotherapeutics between ß-cyclodextrin and anti-cancer drug via inclusion complex (IC). Furthermore, the temperature induced chain association of PNIPAAm segments facilitated the IC to form supramolecular nanoparticles at 37 °C, whereas the presence of PEG impart great stability to the self-assemblies. When incubated with MDR-1 membrane pump regulated drug resistant tumor cells, much higher and faster cellular uptake of the supramolecular nanoparticles were detected, and the enhanced intracellular retention of drugs could lead to significant inhibition of cell growth. Further in vivo evaluation showed high therapeutic efficacy in suppressing drug resistant tumor growth without a significant impact on the normal functions of main organs. This work signifies thermo-responsive supramolecular chemotherapy is promising in combating pump mediated drug resistance in both in vitro and in vivo models, which may be encouraging for the advanced drug delivery platform design to overcome drug resistant cancer.

Synthesis of star-like hybrid POSS-(PDMAEMA-b-PDLA)8 copolymer and its stereocomplex properties with PLLA.

Although poly(lactide) (PLA), when used as biomaterials, possesses many good properties, its high hydrophobicity and slow degradation may hinder its applications. In this work, a novel star-like oligomeric silsesquioxane-(poly(2-dimethylaminoethyl methacrylate)-b-poly(d-lactide))8 (POSS-(PDMAEMA-b-PDLA)8) was first synthesized through a three-step procedure that involves Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization of DMAEMA initiated by the macroinitiator POSS-8-CTA, and then conversion of the trithiocarbonated end groups on PDMAEMA arms into hydroxyl groups by a combination of aminolysis and Michael addition followed by controlled ring-opening polymerization of D-LA. In the next step, the synthesized hybrid copolymer POSS-(PDMAEMA-b-PDLA)8 was blended with PLLA in solution to form nanocomposites to further modify the thermo-mechanical and degradation properties of PLLA. It was noted that the outer PDLA shell could facilitate POSS-(PDMAEMA-b-PDLA)8 to be well-dispersed in PLLA matrix through stereocomplex (SC) interaction, and the inner PDMAEMA shell endowed PLLA with good hydrophilicity. The SC formation between POSS-(PDMAEMA-b-PDLA)8 and PLLA was confirmed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses. The surface wettability of the PLLA was enhanced due to the presence of hydrophilic PDMAEMA segments and the contact angle values decreased with increasing amount of PDMAEMA in the nanocomposites. Meanwhile, controlled degradation of PLLA in a faster pace was achieved when the nanocomposites were incubated in different pH solutions, indicating its potential in specific biomedical applications.

Conjugation of poly(ethylene glycol) to poly(lactide)-based polyelectrolytes: An effective method to modulate cytotoxicity in gene delivery.

Positively charged amphiphilic polymers comprising of poly(N,N-dimethylaminoethyl methacrylate) segments on both sides of a poly(l-lactic acid) segment was conjugated with poly(ethylene glycol) (DMA-PLLA-DMA@PEG). Efficient condensation of plasmid DNA by these polymers was shown. Cell toxicity studies demonstrated that the positively charged polymers with attached PEG exhibited much less cytotoxicity than polymers with no PEG in both HEK293 and Hela cell lines. PEGylation also resulted in polymers with enhanced haemo-compatibility. The positively charged polymers displayed very good DNA plasmid delivery efficiencies in both HEK293 and Hela cells.

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.