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Nanomaterials at the neural interface can provide the bridge between bioelectronic devices and native neural tissues and achieve bidirectional transmission of signals with our brain. Photoactive nanomaterials, such as inorganic and polymeric nanoparticles, nanotubes, nanowires, nanorods, nanosheets or related, are being explored to mimic, modulate, control, or even substitute the functions of neural cells or tissues. They show great promise in next generation technologies for the neural interface with excellent spatial and temporal accuracy. In this review, we highlight the discovery and understanding of these nanomaterials in precise control of an individual neuron, biomimetic retinal prosthetics for vision restoration, repair or regeneration of central or peripheral neural tissues, and wireless deep brain stimulation for treatment of movement or mental disorders. The most intriguing feature is that the photoactive materials fit within a minimally invasive and wireless strategy to trigger the flux of neurologically active molecules and thus influences the cell membrane potential or key signaling molecule related to gene expression. In particular, we focus on worthy pathways of photosignal transduction at the nanomaterial-neural interface and the behavior of the biological system. Finally, we describe the challenges on how to design photoactive nanomaterials specific to neurological disorders. There are also some open issues such as long-term interface stability and signal transduction efficiency to further explore for clinical practice.

Diabetic retinopathy (DR) is a leading cause of irreversible vision loss in working-age populations. FTO is an N6-methyladenosine (m6A) demethylase that participates in various biological events, while its role in DR remains elusive. Herein, we detected elevated FTO expression in retinal proliferative membranes of DR patients. FTO promoted endothelial cell (EC) cell cycle progression and tip cell formation to facilitate angiogenesisin vitro, in mice and in zebrafish. FTO also regulated EC-pericyte crosstalk to trigger diabetic microvascular leakage, and mediated EC-microglia interactions to induce retinal inflammation and neurodegenerationin vivoandin vitro. Mechanistically, FTO affected EC features via modulatingCDK2mRNA stability in an m6A-YTHDF2-dependent manner. FTO up-regulation under diabetic conditions was driven by lactate mediated histone lactylation. FB23-2, an inhibitor to FTO’s m6A demethylase activity, suppressed angiogenic phenotypesin vivoandin vitro. Noteworthy, we developed a nanoplatform encapsulating FB23-2 for systemic administration, and confirmed its targeting and therapeutic efficiencies in mice. Collectively, our study demonstrated that FTO coordinates EC biology and retinal homeostasis in DR, providing a promising nanotherapeutic approach for DR.

Reducing the switching energy and improving the switching speed of ferroelectrics remain an important goal in the pursuit of electronic devices with ultralow energy consumption and ultrafast response. Molecular ferroelectrics with concise dipole switching mechanism and facile structural tunability are a good platform for manipulating the ferroelectric domains. A methodology is demonstrated to manipulation of ferroelectric domain switching by tailor-made lattice parameters of molecular ferroelectrics, by following which, we succeeded in lowering the threshold electric field and improving the dynamics of ferroelectric switching. Our findings advance the fundamental understanding of microscopic mechanism and provide important insights in controllable tuning of ferroelectric domain switching.

Multifunctional materials which generate response under different stimuli are important for sensor and actuator applications. In this work, to achieve multifunctional materials, the composites of P...

Endowing bulk electrocaloric polymers with excellent thermal conductivity is a superior solution to the high-efficient and precise management of tremendous heat from high-power-density electronic devices. Semi-crystalline polymer P(VDF-TrFE-CFE), i.e., poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene), has a predominant amorphous phase of randomly entangled chains and abundant interface, leading to localized behavior in phonon heat conduction and thereby low thermal conductivity. To enhance the thermal transport performance, electrocaloric polymer films were mechanically stretched or fabricated by electrospun to achieve highly aligned molecular chains. Chain orientation brought about a 2.4- and 1.6-times increase in the thermal diffusion coefficient of the stretched and electrospun films, respectively. Interestingly, after mechanical stretching, the thermal conductivity of the film was increased by a factor of two. In contrast, the electrospun film had a slightly lower thermal conductivity than that of the unoriented one. A remarkable discrepancy in the electrocaloric properties was observed, where the stretched polymer film reached a much higher adiabatic temperature change under an applied electric field than that of the electrospun film. Our strategy provides a perspective on designing a promising thermal management system through the integration of active refrigeration and passive heat dissipation in bulk electrocaloric polymers.

2-hydroxynaphthylidene-1′-naphthylamine (HNAN) and −NO2 modified HNAN (HNAN-NO2) Schiff base compounds were synthesized and exhibited strong visible light absorption (

Modern development of flexible electronics has made use of bioelectronic materials as artificial tissue in vivo. As hydrogels are more similar to nerve tissue, functional hydrogels have become a promising candidate for bioelectronics. Meanwhile, interfacing functional hydrogels and living tissues is at the forefront of bioelectronics. The peripheral nerve injury often leads to paralysis, chronic pain, neurologic disorders, and even disability, because it has affected the bioelectrical signal transmission between the brain and the rest of body. Here, a kind of light-stimuli-responsive and stretchable conducting polymer hydrogel (CPH) is developed to explore artificial nerve. The conductivity of CPH can be enhanced when illuminated by near-infrared light, which can promote the conduction of the bioelectrical signal. When CPH is mechanically elongated, it still has high durability of conductivity and, thus, can accommodate unexpected strain of nerve tissues in motion. Thereby, CPH can better serve as an implant of the serious peripheral nerve injury in vivo, especially in the case that the length of the missing nerve exceeds 10 mm.

Interfacial architecture is key in tuning ferroelectric nanocomposites, however, the dynamic process of energy storage and release at the interface still remains mystery. Herein, we experimentally ...

The rapid growth of miniaturized electronic devices has raised the demand for compact, flexible, wearable, and non-volatile memory units. However, integration into nanoelectronic devices requires a scaled-down data-storage component, but this often results in the deterioration of the ferroelectric switching performance. Herein, we demonstrate a simple and scalable fabrication of poly (vinylidene fluoride trifluoroethylene) [P(VDF-TrFE)] film with graphene oxide (GO) nanosheets. Using piezoresponse force microscopy (PFM), the storage features of this multilayer film were investigated, including establishment of two stable memory states, ferroelectric switching dynamics in the point-polarization and linear-polarization modes, and time and thermal stability of information storage. Remarkably, the GO-P(VDF-TrFE) film favored formation of low-temperature (LT) ferroelectric phase with much more ordered sequences of trans conformations relative to pristine P(VDF-TrFE) due to the presence of electrostatic interaction between GO nanosheets and C F dipoles of P(VDF-TrFE), thus affording improved ferroelectric properties. The GO-P(VDF-TrFE) film showed several excellent storage features, such as ultra-high density of more than 300 Gbits in−2, good writing & erasing repeatability, long data retention time, and elevated device operation temperature. In-depth understanding and utilization of the excellent non-volatile memory performance of this new GO-ferroelectric system will open new avenues for the next generation of nanoelectronic devices.

Wireless micro- and nanorobots are biomedical devices with a potential use in high-precision minimally invasive therapies. Here, a highly integrated multifunctional soft microrobot is developed for targeted cell therapy applications, featuring targeted cell transportation and induced cell differentiation. The micromachines are made of composites consisting of a soft piezoelectric polymer matrix in which magnetic nanoparticles are dispersed. The magnetic nanoparticles serve as the component for the device's magnetic actuation, while the piezoelectric polymer acts as both a steerable scaffold and an acoustically responsive cell electrostimulation platform. With the application of a rotating magnetic field, the microrobots swim in a corkscrew motion in different liquid environments that mimic human body fluids. When the swimmers are subjected to acoustic waves, their piezoelectric body is electrically polarized which induces cell differentiation of neuron-like PC12 cells loaded on the swimmers surface. This combinatorial technique may open up new avenues for bioelectronic therapies., Materials Horizons, 6 (7)

Multi-functional electronic skin is of paramount significance for wearable electronics in health monitoring, medical analysis, and human-machine interfacing systems. In order to achieve the function of natural skin, mechanical sensing with high sensitivity is an important feature of electronic skin. Inspired by the spinosum structure under the skin, herein, we fabricate a new capacitive pressure sensor with two-dimensional transition-metal carbides and nitrides (MXene) and ferroelectric polymer (P(VDF-TrFE-CFE)) as an active layer and micropatterned Cr-Au deposited on polydimethylsiloxane as flexible electrodes. Such a method is facile, effective, easily operated, and low-cost. The device design provides great capacitive change as a consequence of large deformation under pressure. Benefiting from the randomly distributed microstructure and high dielectric constant of the active layer, the device demonstrates high sensitivity with great linearity (16.0 kPa−1 for less than 10 kPa), that is, a low detection limit of 8.9 Pa, and quick response. A series of dynamic physiological signals, including typing, knuckle motion, and voice recognition can be facilely detected, making it a competitive candidate in the field of wearable electronics.

The degeneration of dopaminergic neurons is a major contributor to the pathogenesis of mid-brain disorders. Clinically, cell therapeutic solutions, by increasing the neurotransmitter dopamine levels in the patients, are hindered by low efficiency and/or side effects. Here, a strategy using electromagnetized nanoparticles to modulate neural plasticity and recover degenerative dopamine neurons in vivo is reported. Remarkably, electromagnetic fields generated by the nanoparticles under ultrasound stimulation modulate intracellular calcium signaling to influence synaptic plasticity and control neural behavior. Dopaminergic neuronal functions are reversed by upregulating the expression tyrosine hydroxylase, thus resulting in ameliorating the neural behavioral disorders in zebrafish. This wireless tool can serve as a viable and safe strategy for the regenerative therapy of the neurodegenerative disorders.

A high-optical-resolution artificial retina system that accurately communicates with the optic nerve is the main challenge in the modern biological science and bionic field. Here, we developed a bionic artificial retina possessing phototransduction "cells" with measurements even smaller than that of the neural cells. Using the technique of micrometer processing, we constructed a pyramid-shape periodic microarray of a photoreceptor. Each "sensing cell" took advantage of polythiophene derivative/fullerene derivative (PCBM) as a photoelectric converter. Because folic acid played an essential role in eye growth, we particularly modified the polythiophene derivatives with folic acid tags. Therefore, the artificial retina could enlarge the contact area and even recognize the nerve cells to improve the consequence of nerve stimulation. We implanted the artificial retina into blinded rats' eyes. Electrophysiological analysis revealed its recovery of photosensitive function 3 months after surgery. Our work provides an innovative idea for fabricating a high-resolution bionic artificial retina system. It shows great potential in artificial intelligence and biomedicine.

Ferroelectric nanostructures have received much attention because they can be used for the next generation of ferroelectric random-access memory (FeRAM) in flexible electronic devices. Manipulation of domain reversal in ferroelectric nanostructures is extremely important, but rarely studied. Herein, we present generic and reusable fabrication of 2D-confined P(VDF-TrFE) nanodots with an integration density of up to 4 Gbit per inch2, and then investigate the structural maps and the corresponding domain switching kinetics of P(VDF-TrFE) nanodots by atomic force microscope-based (AFM-based) technology. Meanwhile, their storage features, such as precise programmability and data stability, are well characterized by piezoresponse force microscopy (PFM). Remarkably, the ferroelectric crystals in single-confined P(VDF-TrFE) nanodots simultaneously aligned in a plane over the whole patterned region. 2D-confined P(VDF-TrFE) 50 : 50 nanodots has high-temperature ferroelectric (HT FE) phase with all-trans conformations, which endows them with excellent memory characteristics, such as a low operating voltage of 3 V, a short domain nucleation of 100 ms (by V = 10 V), a fast domain growth, an excellent writing–erasing repeatability, and a long retention time. Compared with normal ferroelectric materials, like P(VDF-TrFE) 70 : 30, approximately 150% ratio of energy loss and a 5-fold duration for domain nucleation can be saved. Especially, written domains were well confined in the P(VDF-TrFE) 50 : 50 nanodots, which attains precise programmability on a single nanodot. Our systematic study provides an alternative route for the fabrication of ferroelectric nanostructures that are worth considering for the next generation of flexible FeRAM in all-organic nanoelectronic devices.

Ferroelectric poly(vinylidene fluoride) (PVDF) based polymers are attracting tremendous interest because of their potential applications in flexible non-volatile memories. Current research suggests that the existence of a large hysteresis loop results in high-voltage operation and low writing/erasing speed, which is originated from uniform chain packing and coherent ferroelectric sequences in the crystalline regions. Here, we demonstrate the novel approach to understand the defect-mediated switching mechanisms in ferroelectric polymers by PFM-probe based technology. The single-point and linear polarization reversal is well controlled by defect-mediated ferroelectric phases that determine activation energy, switching rate, and the thermal stability. By the regulation of VDF/TrFE ratio and varying processing conditions, the coherent ferroelectric phase with all-trans sequence in the P(VDF-TrFE) has been disrupted by defects. Specially, the crystallites formed at high temperature in the copolymer P(VDF-TrFE) 50:50 mol% exhibit less ordered ferroelectric crystalline sequences, thus attaining the excellent features of the low operation voltage of about 4 V with a switching time of 100 ms, ultra-high memory density of 43.9 Gbit∙in−2 (by a 7 V, 1 ms pulse) and a high usage temperature of 60 °C. Compared with P(VDF-TrFE) 68:32 mol%, normal ferroelectric, it saves approximate 50% ratio of energy cost, and realizes four times higher resolution. Understanding and controlling defect functionality in ferroelectric materials is as critical for realizing their reliable applications in ferroelectric memories.

High-capacity or high-power-density capacitors are being actively investigated for portable electronics, electric vehicles, and electric power systems. We describe the filler system in dielectric nanocomposites with a small loading of Au nanorods [NRs] to elucidate the mechanism of interfacial crystallization behavior including the crystallization kinetics, and crystalline morphology and structure, and to investigate the intrinsic causes for concurrent great improvements in the dielectric constant and energy density in the nanocomposite system. Remarkly, at high crystallization temperature, the addition of Au NRs, which are used as heterogeneous nucleators, can reduce the nucleation barrier, resulting in accelerating the crystallization rate. However, the crystallization rate slows down at low temperatures because the addition of Au NRs limited the mobility of poly(vinylidene fluoride-chlorotrifluoroethylene) [P(VDF-CTFE)] chains, and thus enhanced the diffusion barrier. Furthermore, the addition of NRs has a huge impact on the crystalline morphology and structure which changes from large paraelectric α-phase spherulites with TGTG' conformations into minor ferroelectric γ-phase spherulites with T3GT3G' conformations, and also produces more exogenous interfaces between the lamellar crystals and amorphous regions, resulting in a higher dielectric constant and higher electric energy density in P(VDF-CTFE)/Au NRs nanocomposites. Our approach provides a facile and straightforward way to design or understand PVDF-based polymers for their practical applications in high-energy-density capacitors.

For next generation of miniaturized personal electronics and pulsed power systems for smart power grids, electric vehicles, and electromagnetic launchers, flexible capacitors from dielectric polymers with high-capacity, high-efficiency, and fast response are highly desirable. Dielectric polymer composite of P(VDF-CTFE), that is poly(vinylidene fluoride-chlorotrifluoroethylene) and a small amount of aromatic polythiourea (PTU) has been described. It combines the merits of both polymers, that is high dipole density and easy processability of P(VDF-CTFE), as well as large dipole moment and high charge–discharge efficiency of PTU. Most impressively, PTU boosts the maximum breakdown strength of P(VDF-CTFE), and thus extracts its maximum energy reserve capacity. PTU also contributes to the promoted charge–discharge efficiency, accelerated discharge, and reduced dielectric loss in P(VDF-CTFE), which facilitate the composite for flexible capacitor applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 193–199

Poly(vinylidene fluoride) (PVDF) based polymers are attracting tremendous interest because of their potential applications in advanced energy storage devices. Fundamental understanding of their crystal structure evolution has been proved elusive due to the nature of rapid crystallization rate. Fortunately, flash differential scanning calorimeter (Flash DSC) with a precise control of cooling rate helps to investigate an understanding of structure–property relationships. For the first time, a bimodal distribution of the crystallization rate of P(VDF-chlorotrifluoroethylene) (CTFE) in the whole temperature range, and a 3D profile of melting point and enthalpy dependence of annealing temperature and time, which is the corresponding crystal structure evolution and the mechanism of crystal nucleation and growth, are revealed by flash DSC. Based on the above conclusions, fast cooling or annealing at low temperature regulates the crystallization behavior, favors a tiny ferroelectric β-phases, drastically reduces paraelectric spherulite sizes, and leads to greatly enhanced energy storage capacity, but reduction in discharged efficiency. For instance, compared with other processing methods, P(VDF-CTFE) quenched by liquid nitrogen achieves the highest discharged energy of 10.6 J cm−3 at the maximum electric field of 270 MV m−1. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 1245–1253

Conjugated polymer nanomaterials (CPNs), as optically and electronically active materials, hold promise for biomedical imaging and drug delivery applications. This review highlights the recent advances in the utilization of CPNs in theranostics. Specifically, CPN-based in vivo imaging techniques, including near-infrared (NIR) imaging, two-photon (TP) imaging, photoacoustic (PA) imaging, and multimodal (MM) imaging, are introduced. Then, CPN-based photodynamic therapy (PDT) and photothermal therapy (PTT) are surveyed. A variety of stimuli-responsive CPN systems for drug delivery are also summarized, and the promising trends and translational challenges are discussed.

Anaerobic bacteria, such as Clostridium and Salmonella, can selectively invade and colonize in tumor hypoxic regions (THRs) and deliver therapeutic products to destroy cancer cells. Herein, we present an anaerobe nanovesicle mimic that can not only be activated in THRs but also induce hypoxia in tumors by themselves. Moreover, inspired by the oxygen metabolism of anaerobes, we construct a light-induced hypoxia-responsive modality to promote dissociation of vehicles and activation of bioreductive prodrugs simultaneously. In vitro and in vivo experiments indicate that this anaerobe-inspired nanovesicle can efficiently induce apoptotic cell death and significantly inhibit tumor growth. Our work provides a new strategy for engineering stimuli-responsive drug delivery systems in a bioinspired and synergistic fashion.

A glucose-responsive closed-loop insulin delivery system mimicking pancreas activity without long-term side effect has the potential to improve diabetic patients’ health and quality of life. Here, we developed a novel glucose-responsive insulin delivery device using a painless microneedle-array patch containing insulin-loaded vesicles. Formed by self-assembly of hypoxia and H2O2 dual-sensitive diblock copolymer, the glucose-responsive polymersome-based vesicles (d-GRPs) can disassociate and subsequently release insulin triggered by H2O2 and hypoxia generated during glucose oxidation catalyzed by glucose specific enzyme. Moreover, the d-GRPs were able to eliminate the excess H2O2, which may lead to free radical-induced damage to skin tissue during the long-term usage and reduce the activity of GOx. In vivo experiments indicated that this smart insulin patch could efficiently regulate the blood glucose in the chemically induced type 1 diabetic mice for 10 h.

Nanoscale design of nanofillers and interfacial architecture are vital to achieve high-capacity and high-energy-conversion efficiency poly(vinylidene fluoride) [(PVDF)-based] nanocomposite materials for vast potential applications in modern electronic devices and electric power systems. Using traditional methods, the addition of ceramic nanoparticles can only produce one type of interface between the nanoparticles and this matrix, achieving an enhanced dielectric constant and energy density at the expense of the charge–discharge efficiency. Herein, we demonstrate a novel class of cross-linking nanofiller system, poly(vinylidene fluoride-chlorotrifluoroethylene)/γ-methacryloylpropyl trimethoxysilane@BaTiO3 [P(VDF-CTFE)/MPS@BT]. This novel approach can not only provide the interfaces between the nanoparticle and the matrix, but also scale down the size of crystalline domains, which results in producing more additional interfaces between the crystalline and amorphous phases to achieve an improved discharged energy density. Remarkably, the smaller crystalline domains, which were characterized by XRD and FTIR spectroscopy, could be beneficial for improving the dipole switchability from the polar phases to non-polar phases during the charge–discharge cycles, leading to unprecedented charge–discharge efficiency. Furthermore, the addition of MPS@BT NPs can regulate two stages of the discharge rate. The early discharge process can be accelerated, while the following stage is obviously delayed. The simplicity of the hierarchical interfacial engineering method provides a promising path to design ferroelectric polymer nanocomposites for dielectric capacitor applications.

A bioinspired photodetector with signal transmissible to neuron cells is fabricated. Photoisomerization of the dye molecules embedded in the ferroelectric polymer membrane achieves electric polarization change under visible light. The photodetector realizes high sensitivity, color recognition, transient response, and 3D visual detection with resolution of 25 000 PPI, and, impressively, directly transduces the signal to neuron cells.

Ferroelectric polymers are of interest as most promising electroactive materials. Flexible transducers from ferroelectric polymer thin film with underneath semiconducting polymer active layer for high sensitive and versatile detection of physiological signals are described. When attached directly on the wrist, the flexible transducers can distinguish the transient pulse waves non-invasively and in situ, due to their fast response (milliseconds) and high sensitivity (down to several Pascal) to instantaneous change of blood pressure. High-resolution picture of one pulse wave is available to provide two most common parameters for arterial stiffness diagnosis. The transducers are also suitable for dynamic recognizing physiological signals under both physical exercise and medicine treatment, demonstrating their enormous potential for warning the risk of cardiovascular disease, and evaluating the efficacy of heart medicines. The transducers are easy to carry around with an operating voltage of 1 V and the power consumption less than 1 μW. Thus, they are valuable for applications like electronic skin and mobile health monitoring.

High-capacity or high-power-density capacitors are being actively investigated for portable electronics, electric vehicles, and electric power systems. The dielectric nanocomposite with a small loading of carboxylic polystyrene (PS-COOH) nanoparticles in poly(vinylidene fluoride-chlorotrifluoroethylene) [P(VDF-CTFE)] matrix, followed by chemical crosslinking has been described. Combination of these two methods significantly improved the capacity of electric energy storage at low electric field. Specially, the nanocomposite with 2 wt % nanoparticles and 15 wt % crosslinking agent achieved a dielectric constant of 17.2 and a discharged energy density of 17.5 J/cm3 (4.9 Wh/L) at an electric field as high as 324 MV/m, while corresponding values for pristine P(VDF-CTFE) are 9.6 and 13.3 J/cm3 (3.7 Wh/L), respectively. Fundamental physics underlying the enhancement in the performance of the nanocomposites with respect to P(VDF-CTFE) is illustrated by solid-state 19F nuclear magnetic resonance of direct excitation or 19F{1H} cross polarization. It revealed different dynamics behavior between crystalline/amorphous regions, and PS-COOH nanoparticles favored the formation of polar γ-form crystals. Small-angle X-ray scattering studies revealed the contribution of the interface to the extraordinary storage of electric energies in the nanocomposites. This approach provided a facile and straightforward way to design or understand PVDF-based polymers for their practical applications in high-energy-density capacitors. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1160–1169

We employed commercially available chip-calorimeter Flash DSC1 to investigate the low-temperature crystallization behaviors of random copolymer P(VDF-TrFE-CFE) (poly(vinylidenefluoride-trifluoroethylene-chlorofluoroethylene)), and compared them to the parallel results of P(VDF-TrFE). The resulted ferroelectric crystalline phases were identified by WAXD and FTIR. We found that, although our P(VDF-TrFE-CFE) contains higher content of VDF sequences than our P(VDF-TrFE), it performs crystallization of the ferroelectric phase at low temperatures much slower, and even exhibits cold crystallization upon heating back from fast cooling. We attributed the slowness to the effect of chemical confinement of large CFE comonomers. Our results facilitate better understanding of structural optimization for the electroactive applications of PVDF-based random copolymers.

Stimuli-responsive and imaging-guided drug delivery systems hold vast promise for enhancement of therapeutic efficacy. Here we report an adenosine-5'-triphosphate (ATP)-responsive and near-infrared (NIR)-emissive conjugated polymer-based nanocarrier for the controlled release of anticancer drugs and real-time imaging. We demonstrate that the conjugated polymeric nanocarriers functionalized with phenylboronic acid tags on surface as binding sites for ATP could be converted to the water-soluble conjugated polyelectrolytes in an ATP-rich environment, which promotes the disassembly of the drug carrier and subsequent release of the cargo. In vivo studies validate that this formulation exhibits promising capability for inhibition of tumor growth. We also evaluate the metabolism process by monitoring the fluorescence signal of the conjugated polymer through the in vivo NIR imaging.

Amide comonomers are common in proteins, which bring chemical confinement to their beta-folding. Furthermore, co-polymerization is a common industrial way to enhance polymer properties. By means of fast-scanning chip-calorimetry (Flash DSC) measurement, we investigated how various amide comonomers (amide 6,6 and amide 12) influence the isothermal crystallization kinetics of polyamide 6. The results show that both amide-6-based random copolymers containing separately 18 mol% of amide 6,6 and 20 mol% of amide 12 crystallize slower than polyamide 6 due to the structural mismatching of amide comonomers in hydrogen-bonding interactions, reflecting the general chemical confinement of co-monomers in copolymer crystallization. However, in the low temperature region, the copolymer holding amide 12 crystallizes even slower than the copolymer holding amide 6,6, opposite to what we usually expected for a higher mobile comonomer of amide 12. We found that the anomalous behavior could be attributed to the temperature region where polyamide 12 crystallizes still slower than polyamide 6,6. Our wide-angle X-ray diffraction results revealed that those amide comonomers retain the habits of their corresponding homopolymers in copolymer crystallization due to their inclusion in the crystalline phase of polyamide 6.

Artificial intelligence refers to the ability of a machine to study and think like a human. In the human brain, these functions rely on changes and transmission of electrical polarization among neurons. Ferroelectric polymer membranes exhibit electrical polarization that is tunable under the action of external stimuli, such as mechanical stresses and electric fields, and they, thus, exhibit signal transmission characteristics similar to those of neurons. In this paper, we describe the fabrication of a flexible computing device based on ferroelectric polymers that are capable of performing Boolean logic operations and have data retention capabilities and high state discrimination down to the nanoscale, thereby enabling dense packaging and low-power logic state switching. It is also able to adhere to human skin. This demonstration of a logical computing system based on polarization will help in the further exploration and development of artificial intelligence.

Advanced Functional Materials, 30 (17), ISSN:1616-3028, ISSN:1616-301X

Brain imaging techniques enable visualizing the activity of central nervous system without invasive neurosurgery. Dopamine is an important neurotransmitter. Its fluctuation in brain leads to a wide range of diseases and disorders, like drug addiction, depression, and Parkinson's disease. We designed near-infrared fluorescence dopamine-responsive nanoprobes (DRNs) for brain activity imaging during drug abuse and addiction process. On the basis of light-induced electron transfer between DRNs and dopamine and molecular wire effect of the DRNs, we can track the dynamical change of the neurotransmitter level in the physiological environment and the releasing of the neurotransmitter in living dopaminergic neurons in response to nicotine stimulation. The functional near-infrared fluorescence imaging can dynamically track the dopamine level in the mice midbrain under normal or drug-activated condition and evaluate the long-term effect of addictive substances to the brain. This strategy has the potential for studying neural activity under physiological condition.

Fluorine-containing polymers or fluorinated polymers with polar covalent bonds between carbon and fluorine atoms are one of the impact dielectric materials in our daily lives. The first synthetic fluoropolymer poly(chlorotrifluoroethylene) was reported by Schloffer and Scherer. As highly nonreactive thermoplastic polymer, poly(vinylidene fluoride) (PVDF) was commercialized by Pennsalt Co. Homopolymerization and copolymerization of fluorinated vinyl monomers have predominantly focused on radical addition reactions in aqueous or nonaqueous media. The controlled radical polymerizations afford a variety of well-defined homopolymers or block copolymers. The fluorinated polymers can also be prepared by chemical modification or reduction of the precursor polymers. The fluorinated polymers could be crystalline, semicrystalline, and amorphous in nature. PVDF and its copolymers represent a class of semicrystalline polymers widely used in electric energy storage and conversion. Their crystalline structures are complicated and determined by the nucleation and crystallization processes. For such semicrystalline materials, numerous crystalline regions, known as polar domains, contribute to prominent dielectric performance. The orientation of carbon-fluoride dipoles in crystalline unit cells leads to a dielectric response in the external electric field, whereas intermolecular interaction plays an important role in energy storage and consumption. Scanning probe microscopy provides polarization information at a nanometer scale. These polymers have been used in organic electronic devices for information storage and electric energy utility, mainly due to their outstanding piezoelectricity, pyroelectricity, and ferroelectricity.

Nanoscale materials are now attracting a great deal of attention for biomedical applications. Conjugated polymer nanoparticles have remarkable photophysical properties that make them highly advantageous for biological fluorescence imaging. We report on conjugated polymer nanoparticles with phenylboronic acid tags on the surface for fluorescence detection of neurotransmitter dopamine in both living PC12 cells and brain of zebrafish larvae. The selective enrichment of dopamine and fluorescence signal amplification characteristics of the nanoparticles show rapid and high-sensitive probing such neurotransmitter with the detection limit of 38.8 nM, and minimum interference from other endogenous molecules. It demonstrates the potential of nanomaterials as a multifunctional nanoplatform for targeting, diagnosis, and therapy of dopamine-relative disease.

A series of ferroelectric polymer ultrathin films on different substrates were fabricated by spin coating. Thickness of the ultrathin films was easy to manipulate through tuning the polymer concentration or spin-coating speed. Crystallisation behaviours of these ferroelectric films on different substrates such as bare silicon, silicon coated with Cr or Au, were investigated by atomic force microscopy. The substrates had remarkable effect on the morphologies of the ferroelectric ultrathin films after annealing. Ferroelectric polymer ultrathin film on bare silicon grew to lamellar crystals, while the ultrathin film on silicon coated with Au came into being ‘ball-like’ crystals which were aggregated by smaller ones. The crystallisation behaviour of ferroelectric ultrathin film on silicon coated with Cr was closely related with its heat history. The film annealed immediately after fabrication generated rodlike crystals, which connected with each other. However, the one annealed after storage for a week in des...

Ferroelectric polymers are among the most promising materials for flexible electronic devices. Highly ordered arrays of the defect-modified ferroelectric polymer P(VDF-TrFE-CFE) (poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene)) are fabricated by nanoimprint lithography for nonvolatile memory application. The defective CFE units reduce the coercive field to one-fifth of that of the un-modified P(VDF-TrFE), which can help minimize the energy consumption and extend the lifespan of the device. The nanoimprint process leads to preferable orientation of polymer chains and delicately controlled distribution of the defects, and thus a bi-stable polarization that makes the memory nonvolatile, as revealed by the pulsed polarization experiment.

Increasing needs for whole-body and in vivo cellular imaging brings about high requirements for diversity and stability of fluorescence probes. We prepared red, yellow, and blue emissive conjugated polymers with good optical properties, excellent photostability, and low cytotoxicity that allowed the colour-coding of liver cancer cells (Bel-7402).

The present study describes a flexible nanoplatform based on electrostatic assembly of conjugated polyelectrolytes (CPEs) and carboxylated multi-walled carbon nanotubes (cMWNTs). It is demonstrated that the obtained nanocomposites inherit intrinsic optical properties of CPEs and characteristic Raman vibration modes of MWNTs, providing a fluorescence-Raman dual-imaging method for intracellular tracking and locating of MWNTs. We suggest that the cellular internalization of the CPE-cMWNT nanocomposites is a surface charge-dependent process. The strengths of this nanoplatform include satisfying biocompatibility, enhanced protein-repellent property, and ease of implementation, making it available for both in vitro and in vivo applications.

A multimodal cancer therapeutic nanoplatform is reported. It demonstrates a promising approach to synergistically regulating the tumor microenvironment. The combination of intracellular reactive oxygen species (ROS) generated by irradiation of photosensitizer and endoplasmic reticulum (ER) stress induced by 2-deoxy-glucose (2-DG) has a profound effect on necrotic or apoptotic cell death. Especially, targeting metabolic pathway by 2-DG is a promising strategy to promote the effect of photodynamic therapy and chemotherapy. The nanoplatform can readily release its cargoes inside cancer cells and combines the advantages of ROS-sensitive releasing chemotherapeutic drugs, upregulating apoptosis pathways under ER stress, light-induced generation of cytotoxic ROS, achieving tumor accumulation, and in vivo fluorescence imaging capability. This work highlights the importance of considering multiple intracellular stresses as design parameters for nanoscale functional materials in cell biology, immune response, as well as medical treatments of cancer, Alzheimer's disease, etc.

The electroactive properties of PVDF-based ferroelectric polymers can be tailored by blending. In order to investigate the tunability of electrocaloric effect (ECE) and ferroelectric responses, blends of ferroelectric relaxor poly(vinylidene difluoride–trifluoroethylene–chlorofluoroethylene) (P(VDF-TrFE-CFE)) terpolymer and normal ferroelectrics poly(vinylidene difluoride–co–trifluoroethylene) (P(VDF–TrFE)) copolymer are studied. At low copolymer content (

Photoinitiated cross-linking of poly(vinylidene fluoride-co-chlorotrifluoroethylene) can offer a significant increase in electric energy storage capacity. This improvement is related to the structural changes in the copolymer crystals brought by cross-linking. Cross-linking favors formation of polar crystalline phase, drastic reduction of spherulite sizes, and increase in copolymer inner interface area. This copolymer case demonstrates the greatly enhanced energy storage behavior, including increased discharge energy density at reduced field strength, and improved capacitor efficiency at relatively high degree of cross-linking, which may facilitate a better design for polymer dielectric materials in their application of high energy density capacitors.

Ferroelectric vinylidene fluoride-trifluoroethylene copolymer [P(VDF-TrFE)] free-standing ultrahigh density (≈75 Gb inch−2) nanodot arrays are successfully fabricated through a facile, high-throughput, and cost-effective nano-imprinting method using disposable anodic aluminum oxide with orderly arranged nanometer-scale pores as molds. The nanodots show a large-area smooth surface morphology, and the piezoresponse in each nanodot is strong and uniform. The preferred orientation of the copolymer chains in the nanodot arrays is favorable for polarization switching of single nanodots. The ferroelectric polymer memory prototype can be operated by a few volts with high writing/erasing speed, which comply with the requirements of integrated circuit. This approach provides a way of directly writing nanometer electronic features in two dimensions by piezoresponse force microscopy probe based technology, which is attractive for high density data storage.

The poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) based ferroelectric and relaxor materials have been proved to be good electrocaloric (EC) materials. To further enhance the EC effect in ferroelectric relaxor terpolymer poly(vinylidene fluoride–trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)), composites such as polymer-polymer blends and nanocomposites filled with inorganic nanoparticles are fabricated and investigated. It is found that the addition of small amount of filler (such as P(VDF-TrFE) or nano-ZrO2) can increase terpolymer’s crystallinity and enhance its relaxor behavior through interface couplings. The increased crystallinity and enhanced relaxor behavior together result in enhanced electrocaloric effect. The results demonstrate the promise of composite approaches in tailoring and enhancing ECE in the relaxor terpolymers.