Polymer Nanoparticles Encased in a Cyclodextrin Complex Shell for Potential Site‐ and Sequence‐Specific Drug Release

Time‐staggered combination chemotherapy strategies show immense potential in cell culture systems, but fail to successfully translate clinically due to different routes of administration and disparate formulation parameters that preclude a specific order of drug presentation. A novel platform consisting of drug‐containing PLGA polymer nanoparticles, stably fashioned with a shell composed of drug complexed with cationic cyclodextrin, capable of releasing drugs time‐ and sequence‐specifically within tumors is designed. Morphological examination of nanoparticles measuring 150 nm highlight stable and distinct compartmentalization of model drugs, rhodamine and bodipy, within the core and shell, respectively. Sequential release is observed in vitro, owing to cyclodextrin shell displacement and subsequent sustained release of core‐loaded drug, kinetics preserved in breast cancer cells following internalization. Importantly, time‐staggered release is corroborated in a murine breast cancer model following intravenous administration. Precise control of drug release order, site‐specifically, potentially opens novel avenues in polychemotherapy for synergy and chemosensitization strategies.     

Directing Osteogenesis of Stem Cells with Drug‐Laden,Polymer‐Microsphere‐Based Micropatterns Generated by Teflon Microfluidic Chips

Human bone tissue is built in a hierarchical way by assembling various cells of specific functions; the behaviors of these cells in vivo are sophisticatedly regulated. However, the cells in an injured bone caused by tumor or other bone‐related diseases cannot properly perform self‐regulation behaviors, such as specialized differentiation. To address this challenge, a simple one‐step strategy for patterning drug‐laden poly(lactic‐co‐glycolic acid) (PLGA) microspheres into grooves by Teflon chips is developed to direct cellular alignment and osteogenic commitment of adipose‐derived stem cells (ADSCs) for bone regeneration. A hydrophilic model protein and a hydrophobic model drug are encapsulated into microsphere‐based grooved micropatterns to investigate the release of the molecules from the PLGA matrix. Both types of molecules show a sustained release with a small initial burst during the first couple of days. Osteogenic differentiated factors are also encapsulated in the micropatterns and the effect of these factors on inducing the osteogenic differentiation of ADSCs is studied. The ADSCs on the drug‐laden micropatterns show stronger osteogenic commitment in culture than those on flat PLGA film or on drug‐free grooved micropatterns cultured under the same conditions. The results demonstrate that a combination of chemical and topographical cues is more effective to direct the osteogenic commitment of stem cells than either is alone. The microsphere‐based groove micropatterns show potential for stem cell research and bone regenerative therapies.     

Self‐Healing Properties of Protein Resin with Soy Protein Isolate‐Loaded Poly(d,l‐lactide‐co‐glycolide) Microcapsules

Self‐healing soy protein isolate (SPI)‐based “green” thermoset resin is developed using poly(d,l ‐lactide‐co‐glycolide)(PLGA) microcapsules containing SPI, as crack healant. The SPI–PLGA microcapsules with an average diameter of 778 nm that contain sub‐capsules are prepared using a water‐in‐oil‐in‐water double‐emulsion solvent evaporation technique. The encapsulation efficiency is found to be high, up to 89%. Thermoset green SPI resin containing the SPI–PLGA microcapsules successfully arrests and retards the microcracks. The healing efficiency is investigated using mode I fracture toughness test for resins containing different concentrations of microcapsules from 5 to 20 wt% and glutaraldehyde as a crosslinker at 9 or 12 wt%. The SPI resin containing 12 wt% glutaraldehyde and 15 wt% microcapsules shows self‐healing efficiency of up to 48%. It is observed that the SPI released from SPI–PLGA microcapsules can react with the excess glutaraldehyde present in the resin when the two come in contact within the microcracks and bridge the two fracture surfaces. The results of this study show for the first time that SPI–PLGA microcapsules can self‐heal protein‐based green resins. The same method can be extended to self‐heal other proteins as well as protein‐based green composites resulting in higher fracture toughness and longer useful life.     

Tetrakis‐(4‐thiyphenyl)methane: Origin of a Reversible 3D‐Homopolymer

The efficient syntheses of tetrakis(thiophenol)methane and of a new poly(disulfide) hyper‐crosslinked polymer based on the former monomer are described. Controlled de‐polymerization as well as surface post‐functionalization are successfully conducted on this novel material. Direct prove of post‐functionalization is obtained through solid‐state fluorescence emission spectroscopy, and the number of unreacted thiol‐functions on the surface of the polymeric material is indirectly quantified by de‐polymerization of the post‐functionalized material.     

Direct Photomodification of Polymer Surfaces: Unleashing the Potential of Aryl‐Azide Copolymers

The possibility to impart surface properties to any polymeric substrate using a fast, reproducible, and industrially friendly procedure, without the need for surface pretreatment, is highly sought after. This is in particular true in the frame of antibacterial surfaces to hinder the threat of biofilm formation. In this study, the potential of aryl‐azide polymers for photofunctionalization and the importance of the polymer structure for an efficient grafting are demonstrated. The strategy is illustrated with a UV‐reactive hydrophilic poly(2‐oxazoline) based copolymer, which can be photografted onto any polymer substrate that contains carbon–hydrogen bonds to introduce antifouling properties. Through detailed characterization it is demonstrated that the controlled spatial distribution of the UV‐reactive aryl‐azide moieties within the poly(2‐oxazline) structure, in the form of pseudogradient copolymers, ensures higher grafting efficacy than other copolymer structures including block copolymers. Furthermore, it is found that the photografting results in a covalently bound layer, which is thermally stable and causes a significant antiadherence effect and biofilm reduction against Escherichia coli and Staphylococcus epidermidis strains while remaining noncytotoxic against mouse fibroblasts.     

Amphiphilic Poly(Amino Acid) Nanoparticles Induce Size‐Dependent Dendritic Cell Maturation

Size‐regulated amphiphilic poly(amino acid) nanoparticles (NPs) composed of poly(γ‐glutamic acid) (γ‐PGA) and the hydrophobic amino acid derivative, L ‐phenylalanine ethyl ester (Phe) are prepared to evaluate the effects of particle size on dendritic cell (DC) uptake of NPs and their immune stimulatory activities as delivery carriers and adjuvants. The size of the Phe‐conjugated γ‐PGA NPs (γ‐PGA–Phe NPs) is easily controlled by regulating the aggregated γ‐PGA–Phe numbers. Each of the differently sized γ‐PGA–Phe NPs could efficiently encapsulate ovalbumin (OVA), and the amount of encapsulated OVA per milligram of NPs is almost the same despite the differences in size. The DC uptake of small NPs is lower than for the larger NPs, but the effect of DC activation by NPs is high in the small sizes. The DC activation is significantly affected by the size of the NPs, which suggests that not only the uptake process of the NPs, but also the surface interactions between the NPs and DCs, is important for the induction of DC maturation. The precisely size‐controllable γ‐PGA–Phe NPs have significant potential as an antigen carrier and vaccine adjuvant. These results should provide guidelines for adjuvant design in the development of an effective vaccine.     

Efficient Polymer Solar Cells Based on Poly(3‐hexylthiophene):Indene‐C70 Bisadduct with a MoO3 Buffer Layer

Polymer solar cells (PSCs) with poly(3‐hexylthiophene) (P3HT) as a donor, an indene‐C₇₀ bisadduct (IC₇₀BA) as an acceptor, a layer of indium tin oxide modified by MoO₃ as a positive electrode, and Ca/Al as a negative electrode are presented. The photovoltaic performance of the PSCs was optimized by controlling spin‐coating time (solvent annealing time) and thermal annealing, and the effect of the spin‐coating times on absorption spectra, X‐ray diffraction patterns, and transmission electron microscopy images of P3HT/IC₇₀BA blend films were systematically investigated. Optimized PSCs were obtained from P3HT/IC₇₀BA (1:1, w/w), which exhibited a high power conversion efficiency of 6.68%. The excellent performance of the PSCs is attributed to the higher crystallinity of P3HT and better a donor–acceptor interpenetrating network of the active layer prepared under the optimized conditions. In addition, PSCs with a poly(3,4‐ethylenedioxy‐thiophene):poly(styrenesulfonate) (PEDOT:PSS) buffer layer under the same optimized conditions showed a PCE of 6.20%. The results indicate that the MoO₃ buffer layer in the PSCs based on P3HT/IC₇₀BA is superior to that of the PEDOT:PSS buffer layer, not only showing a higher device stability but also resulting in a better photovoltaic performance of the PSCs.     

Control of Current Hysteresis of Networked Single‐Walled Carbon Nanotube Transistors by a Ferroelectric Polymer Gate Insulator

Films made of 2D networks of single‐walled carbon nanotubes (SWNTs) are one of the most promising active‐channel materials for field‐effect transistors (FETs) and have a variety of flexible electronic applications, ranging from biological and chemical sensors to high‐speed switching devices. Challenges, however, still remain due to the current hysteresis of SWNT‐containing FETs, which has hindered further development. A new and robust method to control the current hysteresis of a SWNT‐network FET is presented, which involves the non‐volatile polarization of a ferroelectric poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)) gate insulator. A top‐gate FET with a solution‐processed SWNT‐network exhibits significant suppression of the hysteresis when the gate‐voltage sweep is greater than the coercive field of the ferroelectric polymer layer (≈50 MV m^?1). These near‐hysteresis‐free characteristics are believed to be due to the characteristic hysteresis of the P(VDF‐TrFE), resulting from its non‐volatile polarization, which makes effective compensation for the current hysteresis of the SWNT‐network FETs. The onset voltage for hysteresis‐minimized operation is able to be tuned simply by controlling the thickness of the ferroelectric film, which opens the possibility of operating hysteresis‐free devices with gate voltages down to a few volts.     

Copolymer Networks Based on Poly(ω‐pentadecalactone) and Poly(ϵ‐caprolactone)Segments as a Versatile Triple‐Shape Polymer System

Thermo‐sensitive triple‐shape polymers can perform two consecutive shape changes in response to heat. These shape changes correspond to the recovery of two different deformations in reverse order, which were programmed previously at elevated temperature levels (T_mid and T_high) by the application of external stress. Recently, an AB copolymer network was described, which surprisingly exhibited a triple‐shape effect despite being programmed with only one deformation at T_high. Here it is explored whether a copolymer network system can be designed that enables a one‐step deformation process at ambient temperature (cold drawing) as a novel, gentle, and easy‐to‐handle triple‐shape‐creation procedure, in addition to the procedures reported to date, which generally involve deformation(s) at elevated temperature(s). A copolymer‐network system with two crystallizable polyester segments is synthesized and characterized, fulfilling two crucial criteria. These materials can be deformed at ambient temperature by cold drawing and show, even at T_high, which is above the melting points of both switching domains, elongation at break of up to 250%. Copolymer networks with PCL contents of 75 and 50 wt% show a triple‐shape effect after cold drawing with shape‐fixity ratios between 65% and 80% and a total‐shape‐recovery ratio above 97%. Furthermore, in these copolymer networks, the triple‐shape effect can be obtained after a one‐step deformation at T_high. Independent of the temperature at which the deformation is applied (ambient temperature or T_high), copolymer networks that have the same compositions show similar switching temperatures and proportioning of the recovery in two steps. The two‐step programming procedure enables a triple‐shape effect in copolymer networks for an even broader range of compositions. This versatile triple‐shape‐material system based on tailored building blocks is an interesting candidate material for applications in fixation systems or disassembling systems.     

Triphenylphosphonium‐Conjugated Poly(ε‐caprolactone)‐Based Self‐Assembled Nanostructures as Nanosized Drugs and Drug Delivery Carriers for Mitochondria‐Targeting Synergistic Anticancer Drug Delivery

For mitochondria‐targeting delivery, a coupling reaction between poly(ε‐caprolactone) diol (PCL diol) and 4‐carboxybutyltriphenylphosphonium (4‐carboxybutyl TPP) results in the synthesis of amphiphilic TPP‐PCL‐TPP (TPCL) polymers with a bola‐like structure. In aqueous environments, the TPCL polymer self‐assembled via cosolvent dispersion and film hydration, resulting in the formation of cationic nanoparticles (NPs) less than 50 nm in size with zeta‐potentials of approximately 40 mV. Interestingly, different preparation methods for TPCL NPs result in various morphologies such as nanovesicles, nanofibers, and nanosheets. In vitro cytotoxicity results with TPCL NPs indicate IC₅₀ values of approximately 10–60 μg mL^?1, suggesting their potential as anticancer nanodrugs. TPCL NPs can be loaded both with hydrophobic doxorubicin (Dox) and its hydrophilic salt form (Dox·HCl), and their drug loading contents are approximately 2–10 wt% depending on the loading method and the hydrophilicity/hydrophobicity of the drugs. Although Dox·HCl exhibits more cellular and nuclear uptake, resulting in greater antitumor effects than Dox, most drug‐loaded TPCL NPs exhibit higher mitochondrial uptake and approximately 2–7‐fold higher mitochondria‐to‐nucleus preference than free drugs, resulting in superior (approximately 7.5–18‐fold) tumor‐killing activity for most drug‐loaded TPCL NPs compared with free drugs. In conclusion, TPCL‐based nanoparticles have potential both as antitumor nanodrugs themselves and as nanocarriers for chemical therapeutics.     

High‐Performance n‐Channel Thin‐Film Field‐Effect Transistors Based on a Nanowire‐Forming Polymer

A new electrontransport polymer, poly{[N,N′‐dioctylperylene‐3,4,9,10‐bis(dicarboximide)‐1,7(6)‐diyl]‐alt‐[(2,5‐bis(2‐ethyl‐hexyl)‐1,4‐phenylene)bis(ethyn‐2,1‐diyl]} (PDIC8‐EB), is synthesized. In chloroform, the polymer undergoes self‐assembly, forming a nanowire suspension. The nanowire's optical and electrochemical properties, morphological structure, and field‐effect transistor (FET) characteristics are investigated. Thin films fabricated from a PDIC8‐EB nanowire suspension are composed of ordered nanowires and ordered and amorphous non‐nanowire phases, whereas films prepared from a homogeneous PDIC8‐EB solution consist of only the ordered and amorphous non‐nanowire phases. X‐ray scattering experiments suggest that in both nanowires and ordered phases, the PDIC8 units are laterally stacked in an edge‐on manner with respect to the film plane, with full interdigitation of the octyl chains, and with the polymer backbones preferentially oriented within the film plane. The ordering and orientations are significantly enhanced through thermal annealing at 200 °C under inert conditions. The polymer film with high degree of structural ordering and strong orientation yields a high electron mobility (0.10 ± 0.05 cm² V^?1 s^?1), with a high on/off ratio (3.7 × 10⁶), a low threshold voltage (8 V), and negligible hysteresis (0.5 V). This study demonstrates that the polymer in the nanowire suspension provides a suitable material for fabricating the active layers of high‐performance n‐channel FET devices via a solution coating process.     

Ultralong Room‐Temperature Phosphorescence from Amorphous Polymer Poly(Styrene Sulfonic Acid) in Air in the Dry Solid State

Polymer‐based room‐temperature‐phosphorescent (RTP) materials are attractive alternatives to low‐molecular‐weight organic RTP compounds because they can form self‐standing transparent films with high thermal stability. However, their RTP lifetimes in air are usually short (<≈0.4 s). Here, the simple organic amorphous polymer, poly(styrene sulfonic acid) (PSS), exhibits an ultralong RTP lifetime in air when desiccated. The maximum lifetime is 1.22 s, which is three times that of previously reported RTP amorphous organic polymers. The lifetime can be controlled by the PSS molecular weight and by the ratio of sulfonic acid groups introduced into the polymer. The dry polymers should enable unprecedented molecular engineering in organic molecule‐based optoelectronic devices because of the self‐standing and thermal stability attributes.     

Emeraldine Base Polyaniline as an Alternative to Poly(3,4‐ethylenedioxythiophene) as a Hole‐Transporting Layer

The device physics of bilayer polymer light emitting diodes containing either poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene] or ladder‐type methyl‐poly(p‐phenylene) active layers have been determined. The active layer was consistent in thickness and general preparation whilst hole transporting layers spin cast from emeraldine base polyaniline protonated with camphorsulfonic acid, emeraldine base polyaniline protonated with 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid, and emeraldine base polyaniline protonated with polystyrene sulfonated acid, in various ratios of polyaniline to counter ion, were used in order to determine how various spin‐processible polyaniline layers performed relative to a commercially available polystyrene sulfonated acid doped poly(3,4‐ethylenedioxythiophene layer. For poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene] light‐emitting diodes we observe an improvement in performance when using emeraldine base polyaniline protonated with polystyrene sulfonated acid relative to poly(3,4‐ethylenedioxythiophene protonated with polystyrene sulfonated acid, with a maximum device external quantum efficiency of 0.6362 % at a current density of 20.18 mA/cm².     

The Role of Morphology in Optically Switchable Transistors Based on a Photochromic Molecule/p‐Type Polymer Semiconductor Blend

The correlation between morphology and optoelectronic performance in organic thin‐film transistors based on blends of photochromic diarylethenes (DAE) and poly(3‐hexylthiophene) (P3HT) is investigated by varying molecular weight (M_w = 20–100 kDa) and regioregularity of the conjugated polymer as well as the temperature of thermal annealing (rt‐160 °C) in thin films. Semicrystalline architectures of P3HT/DAE blends comprise crystalline domains, ensuring efficient charge transport, and less aggregated regions, where DAEs are located as a result of their spontaneous expulsion from the crystalline domains during the self‐assembly. The best compromise between field‐effect mobility (μ) and switching capabilities is observed in blends containing P3HT with M_w = 50 kDa, exhibiting μ as high as 1 × 10^?3 cm² V^?1 s^?1 combined with a >50% photoswitching ratio. Higher or lower M_w than 50 kDa are found to be detrimental for field‐effect mobility and to lead to reduced device current switchability. The microstructure of the regioregular P3HT blend is found to be sensitive to the thermal annealing temperature, with an increase in μ and a decrease in current modulation being observed as a response to the light‐stimulus likely due to an increased P3HT‐DAE segregation, partially hindering DAE photoisomerization. The findings demonstrate the paramount importance of fine tuning the structure and morphology of bicomponent films for leveraging the multifunctional nature of optoelectronic devices.     

Porous Ti4O7 Particles with Interconnected‐Pore Structure as a High‐Efficiency Polysulfide Mediator for Lithium–Sulfur Batteries

Multifunctional Ti₄O₇ particles with interconnected‐pore structure are designed and synthesized using porous poly(styrene‐b ‐2‐vinylpyridine) particles as a template. The particles can work efficiently as a sulfur‐host material for lithium–sulfur batteries. Specifically, the well‐defined porous Ti₄O₇ particles exhibit interconnected pores in the interior and have a high‐surface area of 592 m² g^?1; this shows the advantage of mesopores for encapsulating of sulfur and provides a polar surface for chemical binding with polysulfides to suppress their dissolution. Moreover, in order to improve the conductivity of the electrode, a thin layer of carbon is coated on the Ti₄O₇ surface without destroying its porous structure. The porous Ti₄O₇ and carbon‐coated Ti₄O₇ particles show significantly improved electrochemical performances as cathode materials for Li–S batteries as compared with those of TiO₂ particles.     

Achieving a High Fill Factor and Stability in Perylene Diimide–Based Polymer Solar Cells Using the Molecular Lock Effect between 4,4′‐Bipyridine and a Tri(8‐hydroxyquinoline)aluminum(III) Core

Two novel perylene diimide (PDI)–based derivatives, Alq₃‐PDI and Alq₃‐PDI 2, are synthesized by flanking a 3D tri(8‐hydroxyquinoline)aluminum(III) (Alq₃) core with PDI and a helical PDI dimer (PDI2) to construct high‐performance small molecular nonfullerene acceptors (SMAs). The 3D Alq₃ core significantly suppresses the molecular aggregation of the resulting SMAs, leading to a well‐mixed blend with a PTTEA donor polymer and weak phase separation. Compared with Alq₃‐PDI , the extended π‐conjugation of Alq₃‐PDI2 results in higher‐order molecular packing, which improves the absorption and phase separation behavior. Thus, the Alq₃‐PDI2 devices have higher J_sc and FF values and better device performance, which are further enhanced by a small amount of 4,4′‐bipyridine (Bipy) as an additive. The coordination between Bipy and the Alq₃ core promotes molecular packing and phase separation, which lower charge recombination and enhanced charge collection in the resulting devices. Therefore, a largely improved J_sc of 15.74 mA cm^?2 and very high FF of 71.27% are obtained in the Alq₃‐PDI2 devices, resulting in a power conversion efficiency of 9.54%, which is the best value reported for PDI‐based polymer solar cells. The coordination can also serve as a “molecular lock,” which prevents molecular motion and thus improves device stability.