The surface-enhanced Raman scattering detection of N-nitrosodimethylamine and N-nitrosodiethylamine via gold nanorod arrays with a chemical linkage of zwitterionic copolymer.

Due to the emerging issue of the contamination of sartan medicines and drinking water with N-nitrosodimethylamine (NDMA) and/or N-nitrosodiethylamine (NDEA), the detection of NDMA/NDEA has become an important theme. In this study, we utilized the focused ion beam (FIB) technique to fabricate gold nanorods (Au NRs) and Surface-enhanced Raman Scattering (SERS) substrates and modified them with 1,2-ethanedithiol to quench the high luminescence excitation background signals derived from the high density of localized surface plasmon resonance. To improve the surface hydrophilicity, zwitterionic copolymer PGMA-r-PSBMA was grafted onto the nanosurface of Au NRs, which was confirmed by contact angle analysis and AFM. Raman spectra of the copolymer were observed to confirm the successful grafting of Au NRs, which was also corroborated by TEM and SEM. The Au NRs could easily trap the small polar NDMA and NDEA molecules in aqueous solution due to strong zwitterionic hydrophilicity. Furthermore, the self-association of the anions and cations of the polymeric chain grafted in the hot spot zone assisted in trapping the NDMA/NDEA polar molecules. The Raman scattering cross-section of NDMA/NDEA molecules could be enhanced through the chemical linkage of 1,2-ethanedithiol and the self-association behavior of the zwitterionic copolymer. Accordingly, for the first time, we detected the characteristic peaks of NDMA/NDEA through SERS with detection limit of 10-8 M for both molecules.

Chitosan production from Paecilomyces saturatus using three monosaccharides via mixture design.

In this study, we demonstrate that chitosan is produced from Paecilomyces saturatus fungi using ternary monosaccharide carbon sources liquid cultivation via mixture design strategy. Sixteen experiments were carried out to obtain regression equations of fungal dry mycelial biomass (W), chitosan ratio (R), and deacetylation degree (DD) for plotting contour lines. Contour lines reveal that the maximum W, R, and DD can be simultaneously obtained in cultivated media containing 20% glucose, 60% fructose and 20% mannitol rather than pure monosaccharide cultivation. Three additional confirmation experiments based on the maximum FuCS deacetylation degree had been performed to confirm to be 92.3% via Fourier-transform infrared spectra. Accordingly, FuCS possessed much better anti-microbial activity on E. coli than commercial chitosan (CrCS). Meanwhile, X-ray diffraction results confirmed that FuCS possessed both α and γ crystalline peaks while CrCS possessed only α crystalline peak, being collaborated with thermogravimetric analysis results. The superior FuCS was obtained by using ternary monosaccharides system in fungal culture via mixture design for the first time. This study provides a new approach to produce chitosan from fungal cultivation by using the mixture design strategy.

Surfactant-Enriched ZnO Surface via Sol-Gel Process for the Efficient Inverted Polymer Solar Cell.

In this study, we demonstrate that the top surface is enriched by surfactants, tetraoctylammonium bromide, and cetylpyridinium bromide (CPB), in the sol-gel ZnO, being evidenced by the Br depth profile of electron spectroscopy for chemical analysis data. X-ray photoelectron spectroscopy results showed the formation of Zn-Br bonding due to the oxygen defects occupied by Br at the surfactant-enriched ZnO surface. The surfactant-enriched ZnO surface possessed a smoother surface and more hydrophobicity than the pristine ZnO from the experimental results of atomic force microscopy and contact angle, respectively. On the basis of ultraviolet photoelectron spectroscopy data, the work function slightly reduced due to the dipole built-up by the electrostatic force between Br- and N+ to enhance the electron extraction ability. The improved properties benefited the power conversion efficiency (PCE) of bulk-heterojunction polymer solar cells (PSCs) by spin-coating the active layer on the surfactant-enriched ZnO surface. The inverted PSCs with the surfactant-enriched ZnO surface showed the highest PCE of 9.55% for the CPB case, in comparison with the pristine ZnO surface (8.08% PCE). This study discloses that turning the ZnO surface is easily achieved by the addition of surfactants with different molecular structures in the sol-gel ZnO for high performance polymer solar cells.

Enhancement of Inverted Polymer Solar Cells Performances Using Cetyltrimethylammonium-Bromide Modified ZnO.

In this study, the performance and stability of inverted bulk heterojunction (BHJ) polymer solar cells (PSCs) is enhanced by doping zinc oxide (ZnO) with 0-6 wt % cetyltrimethylammonium bromide (CTAB) in the sol-gel ZnO precursor solution. The power conversion efficiency (PCE) of the optimized 3 wt % CTAB-doped ZnO PSCs was increased by 9.07%, compared to a PCE of 7.31% for the pristine ZnO device. The 0-6 wt % CTAB-doped ZnO surface roughness was reduced from 2.6 to 1 nm and the number of surface defects decreased. The X-ray photoelectron spectroscopy binding energies of Zn 2p3/2 (1021.92 eV) and 2p1/2 (1044.99 eV) shifted to 1022.83 and 1045.88 eV, respectively, which is related to strong chemical bonding via bromide ions (Br-) that occupy oxygen vacancies in the ZnO lattice, improving the PCE of PSCs. The concentration of CTAB in ZnO significantly affected the work function of PSC devices; however, excessive CTAB increased the work function of the ZnO layer, resulting from the aggregation of CTAB molecules. In addition, after a 120-hour stability test in the atmosphere with 40% relative humidity, the inverted device based on CTAB-doped ZnO retained 92% of its original PCE and that based on pristine ZnO retained 68% of its original PCE. The obtained results demonstrate that the addition of CTAB into ZnO can dramatically influence the optical, electrical, and morphological properties of ZnO, enhancing the performance and stability of BHJ PSCs.

An anti-fouling nanoplasmonic SERS substrate for trapping and releasing a cationic fluorescent tag from human blood solution.

In bioenvironmental detection, surface-enhanced Raman scattering (SERS) signals are greatly affected by anti-specific biomolecule adsorption, which generates strong background noise, reducing detection sensitivity and selectivity. It is thus necessary to modify the SERS substrate surface to make it anti-fouling to maintain excellent SERS signals. Herein, we propose a zwitterionic copolymer, namely poly(glycidyl methacrylate-co-sulfobetaine methacrylate) (poly(GMA-co-SBMA)), for the surface modification of SERS substrates, which were fabricated and characterized spectroscopically. The copolymer was grafted onto Ag nanocubes (NCs) on an Ag surface with massive nanogaps via 1,2-ethanedithiol, which acted as a metal-insulator-metal (MIM) substrate. The high density of poly(GMA-co-SBMA) grafted near NCs favored the formation of connections between adjacent NCs, causing strong surface plasmon resonance at these junctions. With the zwitterionic-copolymer-modified surface, the adhesion of large biomolecules in platelet-rich plasma (PRP) solution can be effectively resisted, as determined from immunoassay and fibrinogen adsorption results. The SERS signals for malachite green (MG) in PRP solution (10-6 M) were effectively distinguished using the copolymer-grafted MIM substrate. MG was deposited on adjacent copolymer-grafted NCs, which amplified the SERS signals. Moreover, the copolymer connected adjacent NCs, inducing the electromagnetic effect at copolymer-grafted surfaces, which improved the SERS mechanism. The hydration process restructured the MG-trapped copolymer-grafted surface, decreasing the number of MG characteristic peak regions and increasing that of the copolymer regions. These results reveal that grafting a copolymer onto an MIM substrate allows MG to be easily trapped and released in complex biomatrices and increases surface reproducibility due to anti-fouling, leading to high SERS enhancement.

NiOx Electrode Interlayer and CH3 NH2 /CH3 NH3 PbBr3 Interface Treatment to Markedly Advance Hybrid Perovskite-Based Light-Emitting Diodes.

The performance of hybrid perovskite-based light-emitting diodes (LEDs) is markedly enhanced by the application of a NiOx electrode interlayer and moderate methylamine treatment. A hybrid perovskite-based LED exhibits a peak luminous efficiency of 15.9 cd A-1 biased at 8.5 V, 407.65 mA cm-2 , and 65 300 cd m-2 , showing a distinctive impact for future applications.

Zwitterionic surface grafting of epoxylated sulfobetaine copolymers for the development of stealth biomaterial interfaces.

UNLABELLED: Most biomaterials have a lack of a simple, efficient and robust antifouling modification approach that limits their potential for biomedical applications. The challenge is to develop a universal surface grafting solution to meet the antifouling requirement. In this work, a new formulation of zwitterionic sulfobetaine-based copolymer, ploy(glycidyl methacrylate-co-sulfobetaine methacrylate) (poly(GMA-co-SBMA)), is designed as a chemical for grafting onto material and is introduced for the surface zwitterionization of versatile biomaterials, including ceramic, metal, and plastics. The grafting principle used to stabilize the poly(GMA-co-SBMA) on the target surfaces is based the base-induced ring opening reaction between epoxied and hydroxyl groups. A universal surface modification procedure was developed and performed from an optimized sequence of ultra-violet ozone pretreatment and trimethylamine-catalyzed zwitterionization on a selective case of versatile surfaces including silicon wafer, ceramic glass, titanium, steel, and polystyrene. The prepared poly(GMA-co-SBMA) with an optimum PGMA/PSBMA ratio of 0.23 and a molecular weight of 25kDa exhibited the best resistance to fibrinogen adsorption with over 90% reduction as well as blood cell activation, tissue cell adhesion and bacterial attachment on the zwitterionic copolymer grafted surfaces. The developed antifouling grafting introduces a universal modification method to generate zwitterionic interfaces on versatile biomaterial substrates, providing great potential for application in medical device coating. STATEMENT OF SIGNIFICANCE: A simple, efficient and robust antifouling modification approach is critical for many scientific interests and industrial applications. In current stage, the existing available zwitterionic modifications suffer from the lack of universal surface grafting solution to achieve the antifouling requirement on versatile biomaterial substrates. In this study, we synthesized and characterized a new zwitterionic sulfobetaine-based copolymer, ploy(glycidyl methacrylate-co-sulfobetaine methacrylate) (poly(GMA-co-SBMA)), which is designed as chemical grafting onto material and introduced for the surface zwitterionization of versatile biomaterials, including ceramic, metal, and plastics. This research have a promising opportunity for the application of stealth biomaterial interfaces on the next generation of medical devices.

Ultra-low fouling and high antibody loading zwitterionic hydrogel coatings for sensing and detection in complex media.

UNLABELLED: For surface-based diagnostic devices to achieve reliable biomarker detection in complex media such as blood, preventing nonspecific protein adsorption and incorporating high loading of biorecognition elements are paramount. In this work, a novel method to produce nonfouling zwitterionic hydrogel coatings was developed to achieve these goals. Poly(carboxybetaine acrylamide) (pCBAA) hydrogel thin films (CBHTFs) prepared with a carboxybetaine diacrylamide crosslinker (CBAAX) were coated on gold and silicon dioxide surfaces via a simple spin coating process. The thickness of CBHTFs could be precisely controlled between 15 and 150nm by varying the crosslinker concentration, and the films demonstrated excellent long-term stability. Protein adsorption from undiluted human blood serum onto the CBHTFs was measured with surface plasmon resonance (SPR). Hydrogel thin films greater than 20nm exhibited ultra-low fouling (<5ng/cm(2)). In addition, the CBHTFs were capable of high antibody functionalization for specific biomarker detection without compromising their nonfouling performance. This strategy provides a facile method to modify SPR biosensor chips with an advanced nonfouling material, and can be potentially expanded to a variety of implantable medical devices and diagnostic biosensors. STATEMENT OF SIGNIFICANCE: In this work, we developed an approach to realize ultra-low fouling and high ligand loading with a highly-crosslinked, purely zwitterionic, carboxybetaine thin film hydrogel (CBHTF) coating platform. The CBHTF on a hydrophilic surface demonstrated long-term stability. By varying the crosslinker content in the spin-coated hydrogel solution, the thickness of CBHTFs could be precisely controlled. Optimized CBHTFs exhibited ultra-low nonspecific protein adsorption below 5ng/cm(2) measured by a surface plasmon resonance (SPR) sensor, and their 3D architecture allowed antibody loading to reach 693ng/cm(2). This strategy provides a facile method to modify SPR biosensor chips with an advanced nonfouling material, and can be potentially expanded to a variety of implantable medical devices and diagnostic biosensors.

Functional p-Type, Polymerized Organic Electrode Interlayer in CH3NH3PbI3 Perovskite/Fullerene Planar Heterojunction Hybrid Solar Cells.

Thermal curing of the styrene-functionalized 9,9-diarylfluorene-based triaryldiamine monomer (VB-DAAF) forms an ideal p-type organic electrode interlayer capable of resisting solvation of the polar precursor solution in fabricating methylammonium lead iodide (CH3NH3PbI3) perovskite/fullerene (C60) planar heterojunction hybrid solar cells. The polymerized VB-DAAF film exhibits a good energy level alignment with the valence-band-edge level of the CH3NH3PbI3 perovskite to facilitate the transport of holes. The large energy barrier to the conduction-band-edge level of the CH3NH3PbI3 perovskite effectively blocks electrons from reaching the positive electrode and reduces the photon energy loss due to recombination. The best-performing cell with the configuration of glass/indium-tin oxide/polymerized VB-DAAF/CH3NH3PbI3 perovskite/C60/bathocuproine/aluminum is free of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PEDOT: PSS) layer to achieve an open-circuit voltage (VOC) = 1.02 V, a short-circuit current (JSC) = 18.92 mA/cm(2), and a fill factor (FF) = 0.78, corresponding to a power conversion efficiency (PCE) of 15.17% under standard 1 sun AM 1.5G simulated solar irradiation. The performance is much superior to the device applying the PEDOT: PSS interlayer with photovoltaic parameters of VOC = 0.85 V, JSC = 16.37 mA/cm(2), and FF = 0.74, corresponding to a PCE of 10.27%. Additionally, we had applied a UV-assisted process to polymerize the VB-DAAF film at relatively lower temperature and fabricate decent perovskite-based solar cells on the flexible substrate for real applications.

Applying thermosettable zwitterionic copolymers as general fouling-resistant and thermal-tolerant biomaterial interfaces.

We introduced a thermosettable zwitterionic copolymer to design a high temperature tolerance biomaterial as a general antifouling polymer interface. The original synthetic fouling-resistant copolymer, poly(vinylpyrrolidone)-co-poly(sulfobetaine methacrylate) (poly(VP-co-SBMA)), is both thermal-tolerant and fouling-resistant, and the antifouling stability of copolymer coated interfaces can be effectively controlled by regulating the VP/SBMA composition ratio. We studied poly(VP-co-SBMA) copolymer gels and networks with a focus on their general resistance to protein, cell, and bacterial bioadhesion, as influenced by the thermosetting process. Interestingly, we found that the shape of the poly(VP-co-SBMA) copolymer material can be set at a high annealing temperature of 200 °C while maintaining good antifouling properties. However, while the zwitterionic PSBMA polymer gels were bioinert as expected, control of the fouling resistance of the PSBMA polymer networks was lost in the high temperature annealing process. A poly(VP-co-SBMA) copolymer network composed of PSBMA segments at 32 mol % showed reduced fibrinogen adsorption, tissue cell adhesion, and bacterial attachment, but a relatively higher PSBMA content of 61 mol % was required to optimize resistance to platelet adhesion and erythrocyte attachment to confer hemocompatibility to human blood. We suggest that poly(VP-co-SBMA) copolymers capable of retaining stable fouling resistance after high temperature shaping have a potential application as thermosettable materials in a bioinert interface for medical devices, such as the thermosettable coating on a stainless steel blood-compatible metal stent investigated in this study.

Nickel oxide electrode interlayer in CH3 NH3 PbI3 perovskite/PCBM planar-heterojunction hybrid solar cells.

This study successfully demonstrates the application of inorganic p-type nickel oxide (NiOx ) as electrode interlayer for the fabrication of NiOx /CH3 NH3 PbI3 perovskite/PCBM PHJ hybrid solar cells with a respectable solar-to-electrical PCE of 7.8%. The better energy level alignment and improved wetting of the NiOx electrode interlayer significantly enhance the overall photovoltaic performance.

p-type Mesoscopic nickel oxide/organometallic perovskite heterojunction solar cells.

In this article, we present a new paradigm for organometallic hybrid perovskite solar cell using NiO inorganic metal oxide nanocrystalline as p-type electrode material and realized the first mesoscopic NiO/perovskite/[6,6]-phenyl C61-butyric acid methyl ester (PC61BM) heterojunction photovoltaic device. The photo-induced transient absorption spectroscopy results verified that the architecture is an effective p-type sensitized junction, which is the first inorganic p-type, metal oxide contact material for perovskite-based solar cell. Power conversion efficiency of 9.51% was achieved under AM 1.5 G illumination, which significantly surpassed the reported conventional p-type dye-sensitized solar cells. The replacement of the organic hole transport materials by a p-type metal oxide has the advantages to provide robust device architecture for further development of all-inorganic perovskite-based thin-film solar cells and tandem photovoltaics.

High voltage and efficient bilayer heterojunction solar cells based on an organic-inorganic hybrid perovskite absorber with a low-cost flexible substrate.

A low temperature (<100 °C), flexible solar cell based on an organic-inorganic hybrid CH3NH3PbI3 perovskite-fullerene planar heterojunction (PHJ) is successfully demonstrated. In this manuscript, we study the effects of energy level offset between a solar absorber (organic-inorganic hybrid CH3NH3PbI3 perovskite) and the selective contact materials on the photovoltaic behaviors of the planar organometallic perovskite-fullerene heterojunction solar cells. We find that the difference between the highest occupied molecular orbital (HOMO) level of CH3NH3PbI3 perovskite and the Fermi level of indium-tin-oxide (ITO) dominates the voltage output of the device. ITO films on glass or on the polyethylene terephthalate (PET) flexible substrate with different work functions are investigated to illustrate this phenomenon. The higher work function of the PET/ITO substrate decreases the energy loss of hole transfer from the HOMO of perovskite to ITO and minimizes the energy redundancy of the photovoltage output. The devices using the high work function ITO substrate as contact material show significant open-circuit voltage enhancement (920 mV), with the power conversion efficiency of 4.54%, and these types of extra-thin planar bilayer heterojunction solar cells have the potential advantages of low-cost and lightweight.

Heterogeneous junction engineering on core-shell nanocatalysts boosts the dye-sensitized solar cell.

In this study, we successfully manipulate the heterogeneous junction at Co3O4-Pt core-shell cathodic nanocatalysts (C/P CNCs) by controlling the core/shell ratios. Our results indicate the cobalt core atoms would inject their valence charge to the surface Pt atoms due to the presence of extensive lattice strain in the shell region. This charge injection accelerates the redox kinetics at the catalysts surface. Consequently, compared with that using Pt nanoparticle cathode, the C/P CNCs at an optimal Pt/Co atomic ratio of 1, improves the current density and the photovoltaic efficiency of dye-sensitized soar cell (DSSC) by ∼36.3% and ∼22.9%, respectively. By combining structure and electrochemical analysis, we systematically elucidate the effects of Pt/Co (shell/core) ratios, the interplay of Co atoms on the shell structures, and the redox activity of C/P CNCs on the DSSC performance. Hereby, this study provide mechanistic insights in developing electrocatalysts for DSSC with programmable performance and reduced Pt utilization.

CH3NH3PbI3 perovskite/fullerene planar-heterojunction hybrid solar cells.

All-solid-state donor/acceptor planar-heterojunction (PHJ) hybrid solar cells are constructed and their excellent performance measured. The deposition of a thin C60 fullerene or fullerene-derivative (acceptor) layer in vacuum on a CH3 NH3 PbI3 perovskite (donor) layer creates a hybrid PHJ that displays the photovoltaic effect. Such heterojunctions are shown to be suitable for the development of newly structured, hybrid, efficient solar cells.

Layer-by-layer assembled titania tubular nanostructures at different assembly conditions.

Layer-by-layer (LbL) deposition of poly(L-lysine) (PLL) dissolved in different solutions and a water-soluble titania precursor, titanium(IV) bis(ammonium lactate) dihydroxide (TiBALDH) to form multilayer films on the wall of polycarbonate (PC) membrane pores was performed to prepare nanostructured titania-PLL composite and pure anatase and rutile titania tubes. A battery of analytical techniques was utilized to characterize and compare the structures, crystal phases, and photocatalytic properties of the titania tubes. In different solutions conditions, PLL which adopts secondary conformations (i.e., alpha-helix and random coil) and has varying interactions with different counterions (i.e., chloride and phosphate ions) can influence PLL/TiBALDH deposition and, in turn, results in the titania materials with different nanostructures and phtocatalytic properties. The influence of LbL assembly condition, deposition cycle, and polypeptide molecular weight on photocatalytic properties of resultant anatase titania tubes were further explored and these materials are promising photocatalyst with the advantage of easily handling and recycling. This reported approach may provide a facile and general way to prepare organic-inorganic composite and other inorganic materials with different compositions, structures, and properties for various applications.

White-emissive tandem-type hybrid organic/polymer diodes with (0.33, 0.33) chromaticity coordinates.

This study reports fabrication of white-emissive, tandem-type, hybrid organic/polymer light-emitting diodes (O/PLED). The tandem devices are made by stacking a blue-emissive OLED on a yellow-emissive phenyl-substituted poly(para-phenylene vinylene) copolymer-based PLED and applying an organic oxide/Al/molybdenum oxide (MoO(3)) complex structure as a connecting structure or charge-generation layer (CGL). The organic oxide/Al/MoO(3) CGL functions as an effective junction interface for the transport and injection of opposite charge carriers through the stacked configuration. The electroluminescence (EL) spectra of the tandem-type devices can be tuned by varying the intensity of the emission in each emissive component to yield the visible-range spectra from 400 to 750 nm, with Commission Internationale de l'Eclairage chromaticity coordinates of (0.33, 0.33) and a high color rendering capacity as used for illumination. The EL spectra also exhibit good color stability under various bias conditions. The tandem-type device of emission with chromaticity coordinates, (0.30, 0.31), has maximum brightness and luminous efficiency over 25,000 cd/m(2) and approximately 4.2 cd/A, respectively.

Bulk-heterojunction polymers in optically-induced dielectrophoretic devices for the manipulation of microparticles.

This paper presents a decent polymer material for fabricating optically-induced dielectrophoretic (ODEP) devices, which can manipulate microparticles or cells by using moving light patterns. A thin film of a bulk-heterojunction (BHJ) polymer, a mixture of regioregular poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester, is used as a light-activated layer. When illuminated by a projected light beam, the photo-induced charge carriers created by the electron transfer of excitons at a donor/acceptor interface in the BHJ layer, disturbs the uniformly-distributed electric field applied on the ODEP devices. A negative DEP force is then generated by virtual electrodes defined by the optical images from a computer-programmable projector to manipulate microparticles, thus providing a functionalized platform for particle manipulation. The effect of the polymer thickness and composition on the magnitude of the generated DEP force has been extensively investigated. The maximum particle drag velocity and the force applied on 20.0 mum diameter polystyrene beads are measured to be approximately 202.2 mum/s and 38.2 pN, respectively, for a device with a 497.3-nm thick BHJ layer. The lifetime of the developed device is also explored (~5 hours), which is sufficient for applications of disposable ODEP devices. Therefore, the BHJ polymer may provide a promising candidate for future ODEP devices capable of nanoparticle and cell manipulation.

In situ UV-Vis spectroelectrochemical studies to identify electrochromic sites in poly(1-naphthylamine) modified by diphenylamine.

Poly(1-napthylamine) (PNPA) was modified by incorporation of diphenylamine (DPA) to result copolymer film on the indium tin oxide (ITO) coated glass electrode using cyclic voltammetry. Detailed static and dynamic UV-Vis spectroelectrochemical studies were performed on the copolymer films to identify the electrochromic sites corresponding to individual DPA and NPA units. Absorbance-wavelength-potential (AWP) profiles were constructed from the dynamic spectroelectrochemical results to infer the electrochromic sites. The advantages of using AWP profile in the analysis of electrochromic sites are discussed.