3-aminopropyl Trimethoxysilane Research Articles

Silica modified sulphonated Poly(ether ether ketone) proton exchange membranes for DMFC application

Herein, we report sol-gel modified sulfonated poly(ether ether ketone) (SPEEK) organo-silane based composite proton exchange membranes for their suitability in direct methanol fuel cells (DMFCs). Different concentrations (0.2–1.5 wt%) of aminopropyl trimethoxysilane (APTES) are incorporated in SPEEK matrix by in-situ sol-gel method. Physico and electrochemical performances of composite membranes are enhanced by induced H-bonding interactions between free –NH2 and –SO3H groups. With increase in APTES concentration to 0.8 wt%, the ionic conductivity illustrates improvement by ⁓80% while IEC and Proton conductivity (Pc) enhances by ∼21% and ∼70%, respectively than SPEEK. To further explore the feasibility of the membranes in DMFC. Methanol crossover resistance is calculated to as low as 5.30 × 10−7 cm2 s−1 and offers highest selectivity of 4.43 S s cm−3 in contrast to 12.55 × 10−7 cm2 s−1 and 0.31 S s cm−3 for SPEEK, respectively. This study reveals that the Si-SPEEK membrane is a potential alternate for DMFC.

Syntheses of APTMS-Coated ZnO: An Investigation towards Penconazole Detection.

Extrinsic chemiluminescence can be an efficient tool for determining pesticides and fungicides, which do not possess any intrinsic fluorescent signal. On this basis, (3-aminopropyl) trimethoxysilane (APTMS)-coated ZnO (APTMS@ZnO) was synthesized and tested as an extrinsic probe for the fungicide penconazole. Several synthetic routes were probed using either a one-pot or two-steps method, in order to ensure both a green synthetic pathway and a good signal variation for the penconazole concentration. The synthesized samples were characterized using X-ray diffraction (XRD), infrared (IR), Raman and ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM) imaging and associated energy-dispersive X-ray (EDX) analysis. The average size of the synthesized ZnO nanoparticles (NPs) is 54 ± 10 nm, in line with previous preparations. Of all the samples, those synthesized in two steps, at temperatures ranging from room temperature (RT) to a maximum of 40 °C, using water solvent (G-APTMG@ZnO), appeared to be composed of nanoparticles, homogeneously coated with APTMS. Chemiluminescence tests of G-APTMG@ZnO, in the penconazole concentration range 0.7-1.7 ppm resulted in a quenching of the native signal between 6% and 19% with a good linear response, thus indicating a green pathway for detecting the contaminant. The estimated detection limit (LOD) is 0.1 ± 0.01 ppm.

Synthesis of functionalized metal-organic framework metal-organic framework (MIL-53)/Chitosan for removing dye and pharmaceuticals

Herein, an eco-friendly biocomposite (metal-organic framework (MIL-53)/Chitosan (biological macromolecule)) was synthesized. MIL-(Fe) (Material Institute of Lavoisier: metal-organic framework) was synthesized and denoted as MIL-53A. The material was modified with different amounts of 3-amino propyl trimethoxy silane for preparing different MILs-53A/NH2. Finally, the surface functionalized metal-organic framework and biological macromolecule (SFMOF/BM) biocomposite was synthesized and characterized using XRD, FESEM, TEM, EDS, BET, TGA, FTIR, and Raman and used to remove emerging pollutants (Direct Red 23 and pharmaceuticals (tetracycline and doxycycline)). Adsorption obeyed a pseudo-second-order kinetic model. The adsorption capacity of the MIL-53A and MIL-53A/NH2 was 3,333 and 10,000 mg/g, respectively. SFMOF/BM had the highest adsorption capacity (12,500 mg/g). Adsorption performance remained high even after five regeneration cycles. The results indicated that SFMOF/BM biocomposite could be used as an environmentally friendly adsorbent of dye and pharmaceuticals. The SFMOF/BM could provide multiple non-covalent interactions to remove different organic pollutants, in which both π-π interactions/stacking and H-bonding are suggested to be responsible for the adsorption of dye, tetracycline, and doxycycline.

Phosphorus-doped deep eutectic solvent-derived carbon dots-modified silica as a mixed-mode stationary phase for reversed-phase and hydrophilic interaction chromatography.

In this work, phosphorus-doped carbon dots (P-DESCDs) were successfully prepared using choline chloride/lactic acid type deep eutectic solvent and phosphoric acid as ingredients, and (3-aminopropyl) trimethoxysilane was used as a bridge to graft P-DESCDs onto the silica surface to obtain a new mixed-mode stationary phase (Sil-P-DESCDs) for reversed-phase and hydrophilic interaction liquid chromatography. The successful preparation ofthe stationary phase was confirmed by laser scanning confocal microscopy, elemental analysis, and Fourier transform infrared spectrometry. Interestingly, the doping of phosphorus greatly improved the separation performance and hydrophilicity of the Sil-P-DESCDs column. The Sil-P-DESCDs column was found to have certain hydrophobicity, hydrogen bonding ability and shape selectivity by Tanaka and Engelhardt standard test mixtures, and a series of hydrophilic and hydrophobic compounds such as alkylbenzenes, polycyclic aromatic hydrocarbons, sulfonamides, aromatic amines, phenols, flavonoids, nucleoside bases, and alkaloids. In addition, the effects of mobile phase ratio, column temperature, flow rate, salt concentration, and pH on the retention of analytes on Sil-P-DESCDs columns were investigated. Finally, the Sil-P-DESCDs column was applied to the qualitative and quantitative analysis of calcein-7-glucoside in the real sample of medicinal Astragalus pellets, and it was found at a concentration of 0.02mg/mL.

Low Release Study of Cefotaxime by Functionalized Mesoporous Silica Nanomaterials

As a third-generation β-lactam antibiotic, cefotaxime shows a broad-spectrum with Gram-positive and Gram-negative bacteria activity and is included in WHO's essential drug list. In order to obtain new materials with sustained release properties, the present research focuses on the study of cefotaxime absorption and desorption from different functionalized mesoporous silica supports. The MCM-41-type nanostructured mesoporous silica support was synthesized by sol-gel technique using a tetraethyl orthosilicate (TEOS) route and cetyltrimethylammonium bromide (CTAB) as a surfactant, at room temperature and normal pressure. The obtained mesoporous material (MCM-41 class) was characterized through nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), N2 absorption-desorption (BET) and Fourier transform infrared spectroscopy (FT-IR), proving a good micro-structured homogeneity (SEM images), a high surface area (BET, 1029 m2/g) correlated with high silanolic activity (Q3/Q4 peak ratio from 29Si MAS-NMR), and an expected uniform hexagonal structure (2-3 nm, HRTEM). In order to non-destructively link the antibiotic compound on the solid phase, MCM-41 was further functionalized in two steps: with aminopropyl trimethoxysilane (APTMS) and glutaraldehyde (GA). Three cefotaxime-loaded materials were comparatively studied for low release capacity: the reference material with adsorbed cefotaxime on MCM-41, MCM-41/APS (aminopropyl silyl surface functionalization) adsorbed cefotaxime material, and APTMS-GA bounded MCM-41-cefotaxime material. The slow-release profiles were obtained by using an on-flow modified HPLC system. A significant improved release capacity was identified in the case of MCM-41/APS/GA-cefotaxime due to the covalent surface grafting of the biological active compound, recommending this class of materials as an effective carrier of bioactive compounds in wound dressing, anti-biofilm coatings, advanced drugs, and other related applications.

Preparation and characterization of bioplastics from silylated cassava starch and epoxidized soybean oils

In this work, a systematic coupling study of silane coupling agent between starch and epoxidized soybean oils (ESO) was carried out. Starch was modified by 3-aminopropyl trimethoxy silane (APMS) with various contents of NaOH. The APMS-modified starch was incorporated with ESO to synthesize the bioplastics by solution casting. As demonstrated by the FTIR spectra, the hydrogen bond interactions among starch molecules were inhibited by the modification. This outcome provided higher interaction and compatibility of starch with ESO, as confirmed by FESEM. TGA showed that the thermal stability of starch decreased considerably after the silylation. In contrast, the produced bioplastics with silylated starch exhibited higher thermal stability than the control sample. Regarding the bioplastics, an obvious increase of tensile strength from 5.78 MPa to 9.29 MPa was obtained. This work suggested a simple and effective modification technique by APMS to improve compatibility of starch/ESO-based bioplastics with superior mechanical and thermal properties.

Eco-Friendly Synthesis of Organo-Functionalized Mesoporous Silica for the Condensation Reaction

Amine-functionalised mesoporous silica was prepared by the sonication method, a green approach. The method used aminopropyl trimethoxy silane as the amine source and tetraethyl orthosilicate as a silica source. We distinguished its performance compared to the amine-functionalised mesoporous silica sample prepared by the co-condensation method. The sonication method offered better catalytic activity. The amine-functionalised material was fully characterised by different characterisation techniques such as X-ray diffraction, FTIR, CHN, and SEM. The 12.8% of amine-functionalised material (12.A-MCM-41-S) gave excellent selectivity (98%) and conversion (95%). The activity remained almost unchanged for four cycles.

Design of Amine-Modified Zr-Mg Mixed Oxide Aerogel Nanoarchitectonics with Dual Lewis Acidic and Basic Sites for CO2/Propylene Oxide Cycloaddition Reactions.

The utilization of CO2 attracts much research attention because of global warming. The CO2/epoxide cycloaddition reaction is one technique of CO2 utilization. However, homogeneous catalysts with both Lewis acidic and basic and toxic solvents, such as DMF, are needed in the CO2/epoxide cycloaddition reaction. As a result, this study focuses on the development of heterogeneous catalysts with both Lewis acidic and basic sites for the CO2 utilization of the CO2/epoxide cycloaddition reactions without the addition of a DMF toxic solvent. For the first time, the Zr–Mg mixed oxide aerogels with Lewis acidic and basic sites are synthesized for the CO2/propylene oxide (PO) cycloaddition reactions. To further increase the basic sites, 3-Aminopropyl trimethoxysilane (APTMS) with -NH2 functional group is successfully grafted on the Zr–Mg mixed oxide aerogels. The results indicate that the highest yield of propylene carbonate (PC) is 93.1% using the as-developed APTMS-modified Zr–Mg mixed oxide aerogels. The as-prepared APTMS-modified Zr–Mg mixed oxide aerogels are great potential in industrial plants for CO2 reduction in the future.

Modification of sodium aluminum silicate hydrate by thioglycolic acid as a new composite capable of removing and preconcentrating Pb(II), Cu(II), and Zn(II) ions from food and water samples

In this paper, sodium aluminum silicate hydrate was synthesized using rice husk as a silicon source and scrap aluminum cans as an aluminum source. Afterward, with the aid of microwave heating, a composite of sodium aluminum silicate hydrate and (3-aminopropyl)trimethoxysilane was facilely synthesized then modified by thioglycolic acid to produce a new composite. Besides, characterization of the synthesized composite was carried out using XRD, FT-IR, TEM, CHN elemental analyzer, nitrogen gas sorption analyzer, and SEM. The XRD pattern of the produced composite shows that there is a halo at 2θ = 25.0°, which means that there is a crystalline structure that is combined with an amorphous background. The SEM and TEM studies indicate that the synthesized composite has a structure similar to cotton. The synthesized composite was utilized for the efficient removal and preconcentration of Pb(II), Cu(II), and Zn(II) ions from food and water samples prior to determination by flame atomic absorption spectrometry. The produced composite has a maximum adsorption capacity of 185.53, 168.92, and 125.94 mg/g for Pb(II), Cu(II), and Zn(II) ions, respectively. The recovery findings demonstrate that the process is accurate, adaptable, and resulted in quantitative separation (greater than95 percent). Furthermore, the % RSD was less than 3.5 percent, indicating good reproducibility. The Langmuir isotherm and pseudo-second-order model fit the experimental results well. The thermodynamic studies established that the adsorption process is spontaneous, chemical, and exothermic. The produced composite was successfully regenerated and used multiple times to remove the metal ions under investigation from aqueous solutions.

Interfacial modification to anomalously facilitate thermal transport through cathode-separator composite in lithium-ion batteries

Effective thermal management is the key to ensuring lithium-ion batteries (LIBs)’ lifetime and performance. However, the high thermal resistance across the cathode-separator interphase considerably limits the fast heat transfer. Adopting the self-assembled monolayers (SAMs) approach, various organic molecules were selected as the heat controllers to modulate the interfacial thermal conductance (ITC) between the cathode, lithium cobalt oxide (LCO), and the separator, polyethylene (PE). Silane-based SAMs molecules with different groups, including –NH2, –SH, and –CH3, were assembled into the LCO-PE composite’s interphase. Through molecular dynamics (MD) simulations, our results demonstrate SAMs molecules-decorated LCO-PE nanocomposites give a notably improved interfacial heat transfer but are of different magnitude. Such difference mainly results from the different non-bonded interactions and compatibility between SAMs molecules and PE. Of the three SAMs molecules, the assembled 3-aminopropyl trimethoxysilane (APTMS) featuring –NH2 groups improves the ITC the most, about 303.29% in comparison with the pristine interface. Furthermore, these findings help elucidate the underlying mechanisms of how SAMs molecules improve heat transfer across the LCO-PE interphase. Specifically, such enhancement is greatly attributed to the unique SAMs molecules, which build the new heat transfer pathways between LCO and PE, straighten SAMs molecules’ morphology, remove the discontinuities in the temperature field, develop the strong non-bonded interactions between SAMs molecules and PE, and strengthen the coupling vibration of two materials. These investigations provide a new perspective for designing composite’s interphase to mediate the heat transfer and achieve more effective thermal management across the interphase.

Rapid Synthesis of Kaolinite Nanoscrolls through Microwave Processing.

Kaolinite nanoscrolls (NScs) are halloysite-like nanotubular structures of great interest due to their ability to superimpose halloysite’s properties and applicability. Especially attractive is the ability of these NScs to serve as reaction vessels for the uptake and conversion of different chemical species. The synthesis of kaolinite NScs, however, is demanding due to the various processing steps that lead to extended reaction times. Generally, three intercalation stages are involved in the synthesis, where the second step of methylation dominates others in terms of duration. The present research shows that introducing microwave processing throughout the various steps can simplify the procedure overall and reduce the synthesis period to less than a day (14 h). The kaolinite nanoscrolls were obtained using two final intercalating agents, aminopropyl trimethoxy silane (APTMS) and cetyltrimethylammonium chloride (CTAC). Both produce abundant NScs, as corroborated by microscopy measurements as well as the surface area of the final products; APTMS intercalated NScs were 63.34 m2/g, and CTAC intercalated NScs were 73.14 m2/g. The nanoscrolls averaged about 1 μm in length with outer diameters of APTMS and CTAC intercalated samples of 37.3 ± 8.8 nm and 24.9 ± 6.1 nm, respectively. The availability of methods for the rapid production of kaolinite nanoscrolls will lead to greater utility of these materials in technologically significant applications.

Electro-optical properties of APS and APhS linkers on silicon thin film: A DFT study

APS (3-Aminopropyl) trimethoxysilane) and APhS (p-Aminophenyl) trimethoxysilane) are the most commonly used linkers on a silicon surface. We investigate the surface properties of the structures, including APS or APhS on a silicon substrate. The studied structures consist of APS or APhS linkers with one, two, or three bonds with a substrate, which is a thin layer of Si with crystal orientation 〈100〉 or 〈111〉. Using a first-principles study based on density functional theory (DFT), we investigated the electronic and optical properties of the silicon-linker interface, such as interface states, orbital location, dielectric function, and photon absorption. The effects of linker type, number of linker-substrate bonds, and crystal orientation on density of states are investigated as a most important electrical property. In addition, we calculated the orbital location and dielectric function in the structures consisting of the substrate with the linker molecules. In this study, we propose techniques to reduce band edge shifts due to surface states and enhance the current mobility in structures with APS or APhS on a silicon substrate. The obtained results show that the use of APS linker molecules instead of APhS can reduce the conduction band shift by up to 50% and the density of interface states are sharply reduced at a depth of approximately 5 Å from the silicon surface. Also, simulation results show that the effect of linkers on the dielectric function can be negligible in the case of using linkers with one or two bonds with the substrate at low energies (lower than 5 eV).

Apoptosis-based topotecan-loaded superparamagnetic drug delivery system: an in vitro study

Biological barriers could be overcome using nanobiotechnology, which promotes the development of nanomaterial-based delivery systems. The primary objective of the present investigation is superparamagnetic iron oxide nanoparticle (SPION) production for the delivery of topotecan to human breast cancer cells (MCF-7). The X-ray diffraction results confirmed the formation of pure SPIONs. The Fourier transform infrared spectra indicated the functional groups related to aminopropyl trimethoxy silane as a coating agent and topotecan. Topotecan-loaded magnetite nanoparticles with an IC50 of approximately 156 μg/ml exhibited dose-dependent cytotoxicity. The polymerase chain reaction method also proved that in the mentioned cell line, topotecan-loaded SPIONs could increase the Bax/Bcl-2 ratio and p53 gene expression. An annexin V/propidium iodide detection assay was done to detect the induction of apoptosis. According to the results, the nanoparticles inhibit the survival of MCF-7 breast cancer cells by boosting apoptosis, which helps slow the growth of tumor cells.

Enhancing oxygen/moisture resistance of quantum dots by short-chain, densely cross-linked silica glass network

Quantum dots (QDs) are facing significant photoluminescence degradation in moisture environment. In QDs-silicone composites, the poor water resistance of silicone matrix makes it easy for water and oxygen molecules to erode QDs. To tackle this issue, we proposed a new QDs protection strategy by introducing short-chain silica precursors onto the QDs’ surface, so that a dense silica passivation layer could be formed onto the QDs nanoparticles. Sol-gel method based on 3-aminopropyl triethoxysilane (APTES), 3-mercaptopropyl trimethoxysilane (MPTMS), and 3-mercaptopropyl triethoxysilane (MPTES) were adopted to prepare the uniform and crack-free QDs-silica glass (QD-glass). Because of the crosslinking of short-chain precursors, the formed silica glass possesses 38.6% smaller pore width and 68.6% lower pore volume than silicone, indicating its denser cross-linked network surrounding QDs. After 360 h water immersion, the QDs-glass demonstrated a 6% enhancement in red-light peak intensity, and maintained a stable full width at half maximum (FWHM) and peak wavelength, proving its excellent water-resistant ability. However, the conventional QDs-silicone composites not only showed a decrease of 75.3% in red-light peak intensity, but also a broadened FWHM and a redshifted peak wavelength after water immersion. QDs-glass also showed superior photostability after 132 h exposure to blue light. Red-light peak intensity of QDs-glass remained 87.3% of the initial while that of QDs-silicone decreased to 19.8%. And the intensity of QDs-glass dropped to 62.3% of that under 20 °C after thermal treatment of 160 °C. Besides, under increasing driving currents, the light conversion efficiency drop of QDs-glass is only one fifth that of QDs-silicone. Based on the QDs-glass, the white light-emitting diodes was achieved with a high luminous efficiency of 126.5 lm W−1 and a high color rendering index of 95.4. Thus, the newly proposed QD-glass has great significance in guaranteeing the working reliability of QDs-converted devices against moisture and high-power environment.

Separation of organic contaminant (dye) using the modified porous metal-organic framework (MIL)

Herein, the porous metal-organic framework (MIL-88B: Materials Institute Lavoisier) was synthesized and identified by FT-IR (Fourier transform infrared), SEM (Scanning Electron Microscopy), EDS (Energy Dispersive X-Ray Spectroscopy), and XRD (X-ray powder diffraction) analyses. Then MIL-88B was modified using 3-aminopropyl trimethoxy silane and presented as NH2-MIL-88B. The synthesized materials were used to separate direct red dye 23 (DR23) as an organic contaminant from water. The effect of various important factors such as the amount of adsorbent, initial concentration of contaminants, and pH was investigated. The results showed that the modified adsorbent (NH2-MIL-88B) had a higher adsorption capacity than the row adsorbent (MIL-88B). The amount of dye adsorption is high at lower pH values. The percentage of DR23 dye removal was complete under optimal conditions. Increasing the amount of adsorbent (0.001–0.003 g) and decreasing the pH (2.1–8.1) increases the percentage of dye removal and increasing the concentration of contaminant (50–125 mg/L) reduces the dye removal in the process. Isotherm data showed that the adsorption process followed the Langmuir model. Also, pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic models were used to investigate the adsorption kinetics. Dye adsorption followed pseudo-second-order kinetics with correlation coefficient (0.99 <). The results showed that the modified adsorbent could be used as a suitable adsorbent with a high adsorption capacity for dye removal from water.

Modification of silica nanoparticles with 1-hydroxy-2-acetonaphthone as a novel composite for the efficient removal of Ni(II), Cu(II), Zn(II), and Hg(II) ions from aqueous media

In this paper, a novel composite based on the formation of Schiff base on silica nanoparticles was facilely synthesized. Firstly, silica nanoparticles, which contain silanol groups (Si-OH), were modified with (3-aminopropyl)trimethoxysilane. Then, the modified silica reacted with 1-hydroxy-2-acetonaphthone to form a novel Schiff base/silica composite. The synthesized composite was characterized using several tools such as XRD, FT-IR, FE-SEM, N2 adsorption/desorption analyzer, and CHN analyzer. The considerable reduction at 2θ = 21.9° in the intensity of the XRD peak of the composite is owing to the formation of the Schiff base. Also, the observed FT-IR bands in the composite at 3440 and 1604 cm−1 are owing to the stretching and bending vibrations of OH and/or CN, respectively. The FE-SEM images confirmed that the silica includes irregular shapes whereas the composite possesses a flaky surface owing to the formation of the Schiff base. Elemental analysis of the composite demonstrated that the % C, % H, and % N are 15.26, 3.24, and 1.65 %, respectively. The BET surface area and total pore volume of the composite were reduced because the formed Schiff base blocks the pores of silica. The synthesized composite was employed for the efficient removal of Ni(II), Cu(II), Zn(II), and Hg(II) ions from aqueous media. The maximum uptake capacity of the composite toward Cu(II), Hg(II), Zn(II), and Ni(II) ions is 68.630, 50.942, 45.126, and 40.420 mg/g, respectively. The adsorption processes of the studied metal ions were spontaneous, chemical, and well described using the pseudo-second-order kinetic model and Langmuir equilibrium isotherm. The synthesized composite can be successfully regenerated and utilized various times in the removal of studied metal ions from aqueous media.

A fluorescence turn-on biosensor utilizing silicon-containing nanoparticles: Ultra-sensitive sensing for α-glucosidase activity and screening for its potential inhibitors

A facile and sensitive method for sensing α-glucosidase (α-glu) and screening its inhibitors based on fluorescence monitoring of water-solute silicon-containing nanoparticles (Si CNPs) was proposed and demonstrated. Such fluorescent nanoparticles can be easily produced by mixing (3-aminopropyl) trimethoxysilane (APTMS) and ascorbate sodium (AS) (both without fluorescence signals) at room temperature and pressure. If the ascorbate sodium was replaced by L-ascorbic acid-2-O-α-D-glucopyranosyl (AA2G), which can be hydrolyzed into the former by α-glu, the fluorescence “turn-on” biosensor for α-glu activity can be established. The sensing platform showegd a linear relationship from 10 to 140 U/L and a low detection limit of 0.42 U/L, which is superior to most approaches that have been reported. However, the hydrolysis procedure and subsequent fluorogenic reaction could be blocked in the presence of α-glu inhibitors (AGIs), giving the possibilities of screening various inhibitors from different compounds. Furthermore, detection in human serum and applications in AGIs screening by using this method were also constructed, and showed satisfying results as well. It is proved that this developed biosensor can provide an alternative strategy for potential clinic diagnosis and medicine development.

Formation of a Fully Anionic Supported Lipid Bilayer to Model Bacterial Inner Membrane for QCM-D Studies.

Supported lipid bilayers (SLBs) on quartz crystals are employed as versatile model systems for studying cell membrane behavior with the use of the highly sensitive technique of quartz crystal microbalance with dissipation monitoring (QCM-D). Since the lipids constituting cell membranes vary from predominantly zwitterionic lipids in mammalian cells to predominantly anionic lipids in the inner membrane of Gram-positive bacteria, the ability to create SLBs of different lipid compositions is essential for representing different cell membranes. While methods to generate stable zwitterionic SLBs and zwitterionic-dominant mixed zwitterionic–anionic SLBs on quartz crystals have been well established, there are no reports of being able to form predominantly or fully anionic SLBs. We describe here a method for forming entirely anionic SLBs by treating the quartz crystal with cationic (3-aminopropyl) trimethoxysilane (APTMS). The formation of the anionic SLB was tracked using QCM-D by monitoring the adsorption of anionic lipid vesicles to a quartz surface and subsequent bilayer formation. Anionic egg L-α-phosphatidylglycerol (PG) vesicles adsorbed on the surface-treated quartz crystal, but did not undergo the vesicle-to-bilayer transition to create an SLB. However, when PG was mixed with 10–40 mole% 1-palmitoyl-2-hydroxy-sn-glycero-3-phospho-(1′-rac-glycerol) (LPG), the mixed vesicles led to the formation of stable SLBs. The dynamics of SLB formation monitored by QCM-D showed that while SLB formation by zwitterionic lipids followed a two-step process of vesicle adsorption followed by the breakdown of the adsorbed vesicles (which in turn is a result of multiple events) to create the SLB, the PG/LPG mixed vesicles ruptured immediately on contacting the quartz surface resulting in a one-step process of SLB formation. The QCM-D data also enabled the quantitative characterization of the SLB by allowing estimation of the lipid surface density as well as the thickness of the hydrophobic region of the SLB. These fully anionic SLBs are valuable model systems to conduct QCM-D studies of the interactions of extraneous substances such as antimicrobial peptides and nanoparticles with Gram-positive bacterial membranes.

Study of the substrate surface treatment of flexible polypyrrole-silver composite films on EMI shielding effectiveness: theoretical and experimental investigation

Abstract Conductive flexible polypyrrole-silver (PPy-Ag) composite films were prepared on Biaxial Oriented Polyethylene Terephthalate (BOPET) substrate with surfaces treated by (3-aminopropyl) trimethoxysilane (APTMS). The surface treatment was carried out to improve the adhesion, morphology, and electrical properties of the deposited film to enhance the Electromagnetic Interference Shielding Effectiveness (EMI-SE). APTMS grafting on the BOPET substrate was confirmed by X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM) analyses. All structural, morphological, and electrical features of PPy-Ag raised from different AgNO3 molar ratio were investigated. The shielding effectiveness properties, experimentally determined for the synthesized PPy-Ag films were compared to those simulated analytically and numerically based on the transmission line matrix method (TLM). Both analytical and numerical models showed a good agreement with experimental measurements. The obtained results confirmed that the PPy-Ag films of 0.5 M/1 M molar ratio exhibits high EMI shielding performance of about 21 dB along with an electrical conductivity of 47 S/cm. Therefore, the treated surface flexible PPy-Ag films can be considered as potential candidate for high frequency electromagnetic interference shielding applications.

Preparation and multiple applications of integrated Zn-Al layered double hydroxide@polydopamine nanocomposites

The preparation and application of inorganic-organic hybrid nanomaterials is a hot research topic at present. Herein, we combined Zn-Al layered double hydroxide (Zn-Al LDH) with mesoporous polydopamine (MPDA) to prepare two integrated Zn-Al LDH@MPDA nanocomposites under the modification of linker (1,3,5-benzoyl chloride (TMC) or (3-aminopropyl) trimethoxysilane (APTMS)), namely Composite T (modified by TMC) and Composite A (modified by APTMS), which were then evaluated for dye adsorption, adriamycin hydrochloride (DOX) loading, photothermal conversion experiment, and antibacterial test. The characterization results showed that MPDA can be successfully loaded on Zn-Al LDH with the modification of the two linkers, but the specific surface area, pore-volume, average pore size, and electronegativity of Composite T were all higher than those of composite A, thus being more advantageous in adsorption of cationic dye. Composite T possesses a high loading capacity for DOX, whose loading efficiency and encapsulation efficiency are 478.3% and 95.7%, respectively. In addition, Composite T also shows a high photothermal conversion efficiency of 27.9%. Furthermore, Composite T exhibits excellent antibacterial activity against Escherichia coli (E. coli) and Staphylococus aureus (S. aureus). Therefore, the designed Zn-Al LDH@MPDA nanocomposites would be a promising candidate for a myriad of industrial application fields.