Highly sensitive plasmonic paper substrate fabricated via amphiphilic polymer self-assembly in microdroplet for detection of emerging pharmaceutical pollutants.

We report an innovative and facile approach to fabricating an ultrasensitive plasmonic paper substrate for surface-enhanced Raman spectroscopy (SERS). The approach exploits the self-assembling capability of poly(styrene-b-2-vinyl pyridine) block copolymers to form a thin film at the air-liquid interface within the single microdroplet scale for the first time and the subsequent in situ growth of silver nanoparticles (AgNPs). The concentration of the block copolymer was found to play an essential role in stabilizing the droplets during the mass transfer phase and formation of silver nanoparticles, thus influencing the SERS signals. SEM analysis of the morphology of the plasmonic paper substrates revealed the formation of spherical AgNPs evenly distributed across the surface of the formed copolymer film with a size distribution of 47.5 nm. The resultant enhancement factor was calculated to be 1.2 × 107, and the detection limit of rhodamine 6G was as low as 48.9 pM. The nanohybridized plasmonic paper was successfully applied to detect two emerging pollutants-sildenafil and flibanserin-with LODs as low as 1.48 nM and 3.45 nM, respectively. Thus, this study offers new prospects for designing an affordable and readily available, yet highly sensitive, paper-based SERS substrate with the potential for development as a lab-on-a-chip device.

Alginate-modified surfactants functionalized metal-organic framework-based fluorescent film sensors for detection and adsorption of volatile aldehydes in water.

Volatile aldehydes have an adverse impact on both human health and the environment, therefore, a fast, straightforward, highly accurate detection technique for the simultaneous detection and removal of several aldehydes is eagerly anticipated. Herein, novel APGF@ZIF-8 and APOF@ZIF-8 sensing materials were developed by coating fluorescent alginate-modified surfactants (APGF and APOF) into the ZIF-8 MOFs to produce quite porous fluorescent sensors (SBET up to 1519 m2/g). The detection capacity of the prepared sensors for benzaldehyde, glyoxal, formaldehyde, and acetaldehyde has been examined. The detection mechanism was suggested as hydrogen bonding formation between the sensors and volatile aldehydes as confirmed by Gaussian calculations. All the fluorescence spectra of aldehydes display remarkable linear detection relationships in the range of 0.05-200 µM with the limits of detection (LOD) values in the range of 0.001-0.18 µM (0.106-10.44 ppb). These sensors were utilized successfully to detect multiple volatile aldehydes in river water samples with satisfactory recoveries of 96-107 %. Interestingly, fluorescent APGF@ZIF-8/CS and APOF@ZIF-8/CS films as portable disposable removal techniques for benzaldehyde, glyoxal, formaldehyde, and acetaldehyde from water were fabricated. APOF@ZIF-8/CS exhibited an excellent formaldehyde adsorption capacity of 58.30 mg/g and an adsorption removal efficiency of 93.5 %. The adsorption process of biosorbent on various aldehydes was fitted by Freundlich adsorption isotherm. The adsorption kinetics followed Pseudo-second-order kinetic model.

Fluorescence Naphthalene Cationic Schiff Base Reusable Paper as a Sensitive and Selective for Heavy Metals Cations Sensor: RSM, Optimization, and DFT Modelling.

Heavy metals are particularly damaging contaminants in the environment, and even trace concentrations represent a risk to human health due to their toxicity. To detect the heavy metals of Mn2+ and Co2+ ions, a novel selective reusable paper-based Fluorescence naked-eye sensor based on naphthalene cationic Schiff base (NCSB) was synthesized and confirmed using FT-IR, 1 H-NMR, and MS tools. Based on a blue to colorless color change in the aqueous solution, the NCSB sensor is utilized to Mn2+ and Co2+ cations selectively among other metal ions (Fe2+, Cu2+, Mg2+, Ni2+, Zn2+, Cd2+, Hg2+, Pb2+, Sn2+ and Cr3+). In the aqueous medium, the NCSB sensor displayed high sensitivity, with limits of detection (LOD) values of 0.014 µM (14.08 nM) and 0.041 µM (41.47 nM) for Mn2+ and Co2+ cations, respectively. The paper-based sensor naked-eye detected Mn2+ and Co2+ cations in water at concentrations as low as 0.65 µM (65 nM) and 0.086 µM (86 nM), respectively. It was discovered that 5 min of incubation time and a pH range of 7 to 11 were optimal for the complexation reaction between the Mn2+ and Co2+ ions and the NCSB sensor. Through a static quenching process, the interaction of the different metal ions with the Schiff base group in the NCSB molecule results in the development of a ground-state non-fluorescent complex. NCSB sensor was also successfully applied in analysis of Mn2+ and Co2+ in environmental water with good recoveries of 94.8-105.9%. The theoretical calculations based on density functional theory (DFT) studies are in support of experimental interpretations. The links between the input factors and the anticipated response were evaluated using the quadratic model of the response surface methodology (RSM) modeling.

Selective dual detection of Hg2+ and TATP based on amphiphilic conjugated polythiophene-quantum dot hybrid materials.

The design of multifunctional sensors based on biocompatible hybrid materials consisting of conjugated polythiophene-quantum dots for multiple environmental pollutants is a promising strategy for the development of new monitoring technologies. Herein, we present a new approach for the "on-off-on" sensing of Hg2+ and triacetone triperoxide (TATP) based on amphiphilic polythiophene-coated CdTe QDs (PQDs, PLQY ∼78%). The emission of the PQDs is quenched by Hg2+ ions via electron transfer interactions. Based on the strong interaction between TATP and Hg2+ ions, the addition of TATP to the PQD-Hg2+ complex results in a remarkable recovery of the PQD emission. Under the optimized conditions, the PQD sensor shows a good linear response to Hg2+ and TATP with detection limits of 7.4 nM and 0.055 mg L-1, respectively. Furthermore, the "on-off-on" sensor demonstrates good biocompatibility, high stability, and excellent selectivity in the presence of other metal ions and common explosives. Importantly, the proposed method can be used to determine the level of Hg2+ and TATP in environmental water samples.

Preparation, Properties, and Microbial Impact of Tungsten (VI) Oxide and Zinc (II) Oxide Nanoparticles Enriched Polyethylene Sebacate Nanocomposites.

Nanoparticles of tungsten oxide (WO3) and zinc oxide (ZnO) enriched polyethylene sebacate (PES) nanocomposites were prepared through the coprecipitation process and condensation polymerization reaction. The obtained nano-sized particles of WO3 and ZnO, PES, and nanocomposites (WO3-PES NC and ZnO-PES NC) were investigated. The average molecular weight of the cured PES was measured by employing the gel permeation chromatography (GPC) technique. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) spectra assured the formation of the polymeric nanocomposites.WO3 and ZnO nanoparticles supposed a condensed porous spherical phase found implanted in the polymer structure, as detected by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. These nano-scale systems achieved an electrical activity based on the conductive nanoparticles embedded matrix as a result of the ion-ion interactions. The microbial influence of the nanocomposites was examined against pathogenic bacteria; Pseudomonas aeruginosa,Escherichia coli, Staphylococcus aureus, and Bacillus subtilis, and Fungi; Aspergillus niger, and Candidaalbicans. Results exhibited that these nanocomposites have antimicrobial effects from moderate to slightly high on bacteria and high on fungi which was confirmed by a clear zone of inhibition. This study contributes to the design of reasonable composites to be under evaluation for their catalytic effect.

Solvent-resistant microfluidic paper-based analytical device/spray mass spectrometry for quantitative analysis of C18 -ceramide biomarker.

We developed a highly efficient and low-cost organic solvents-resistant microfluidic paper-based analytical device (µPAD) coupled with paper spray mass spectrometry (PS-MS) for quantitative determination of C18 -ceramide as a prognostic biomarker for several diseases. Several models of µPAD patterns have been examined to select the most resistant and efficient microchannel barriers, which can provide continuous spray at ionization zone and prevent "coffee ring" effect. Moreover, the developed µPAD has enabled the analysis of low concentration of C18 -ceramide because of the maximum supply of deposited analyte through microchannel. The MS results confirmed the formation of doubly and singly charged metal ion complexes between ceramide and different metal ions. Notably, the complexation that occurs between lithium ions and C18 -ceramide showed a high relative abundance compared with other formed complexes. Taking into account the relative abundance of complex [Cer + Li]+ at 572.8 m/z, it can be considered as a stable ion and therefore be used for the analysis of C18 -ceramide at low concentrations. Complexation of C18 -ceramide and lithium confirmed with quantum chemical calculations. The proposed method represents good linearity with a regression coefficient of 0.9956 for the analysis of C18 -ceramide and reaches a limit of detection to 0.84 nM. It has been adapted successfully for practical application in human serum samples with high recovery values in range of 92%-105%. The developed µPAD-MS technique provides clear advantages by reducing the experimental steps and simplifying the operation process and enables to identify subnanomolar concentration of C18 -ceramide in human serum samples.

Novel "turn on-off" paper sensor based on nonionic conjugated polythiophene-coated CdTe QDs for efficient visual detection of cholinesterase activity.

An increasing number of patients are living with Alzheimer's disease (AD); thus, the need for a method to detect AD early and sensitively has become urgent, and the demand for an intelligent analytical platform is growing year by year. Abnormal levels of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are known to be indicative of AD. In this work, a novel conjugated polythiophene (CP) compound was successfully combined with CdTe quantum dots (QDs) to improve their selectivity and sensitivity. The QDs successfully enabled the detection of low concentrations of AChE by turning on the fluorescence of the CdTe/CP via the interaction between CP and thiocholine produced by ATCh hydrolysis and aggregation induced emission enhancement (AIEE). Under optimal conditions, we reached a low detection limit of 0.14 U L-1, which is 7.9 times lower than that of pristine QDs. More importantly, an efficient, inexpensive, and disposable paper-based platform, which allows the efficient visual detection of AChE activity via the color variation of CdTe/CP, was designed. Moreover, the accuracy of the method was demonstrated by conducting a recovery test in human serum, in which the recoveries reached 107% and 110%, proving that CdTe/CP has considerable potential to be used for analyzing real biological samples. The advantages of this method are its simplicity, fast detection capability, affordability, and the fact that it can be used for on-site detection of AChE activity. Furthermore, it has certain guiding significance for detecting AD.

Dual emission nonionic molecular imprinting conjugated polythiophenes-based paper devices and their nanofibers for point-of-care biomarkers detection.

Enzyme-based assays have been extensively used for the early diagnosis of disease-related biomarkers. However, these assays are time-consuming, resource-intensive, and infrastructure-dependent, which renders them unsuitable and impractical for use in resource-constrained areas. Thus, there is a strong demand for a biocompatible and potentially generalizable sensor that can rapidly detect cancer biomarkers at ultralow concentration. Herein, an enzyme-free, cost-efficient, and easy-to-use assay based on a novel approach that entails fluorescent molecularly imprinting conjugated polythiophenes (FMICPs) for cancer biomarkers detection is developed. The promising conjugated polythiophenes structure, with a PLQY as high as 55%, provides a straightforward, and affordable method for free-enzyme signal generation. More importantly, the feasibility of integrating printed-paper technology with a sensitive and cost-effective smartphone and portable prototype testing device that could be utilized for rapid point-of-care (POC) cancer diagnostics is successfully introduced. Significantly, the unique structure of FMICP nanofibers (FMICP NFs) displays superior performance with enhanced sensitivity that is 80 times higher than that of pristine FMICP. This assay could lower the limits of detection to 15 fg mL-1 and 3.5 fg mL-1 for α-fetoprotein (AFP) and carcinoembryonic antigen (CEA), respectively, which are three orders of magnitude exceeding that of the standard enzyme-based assay. Moreover, the developed sensors are successfully applied to the fast diagnosis of AFP in liver cancer patients and the FMICP and FMICP NFs results are in excellent agreement with those of clinical ELISA.

Recent Advances in Nanomicelles Delivery Systems.

The efficient and selective delivery of therapeutic drugs to the target site remains the main obstacle in the development of new drugs and therapeutic interventions. Up until today, nanomicelles have shown their prospective as nanocarriers for drug delivery owing to their small size, good biocompatibility, and capacity to effectively entrap lipophilic drugs in their core. Nanomicelles are formed via self-assembly in aqueous media of amphiphilic molecules into well-organized supramolecular structures. Molecular weights and structure of the core and corona forming blocks are important properties that will determine the size of nanomicelles and their shape. Selective delivery is achieved via novel design of various stimuli-responsive nanomicelles that release drugs based on endogenous or exogenous stimulations such as pH, temperature, ultrasound, light, redox potential, and others. This review summarizes the emerging micellar nanocarriers developed with various designs, their outstanding properties, and underlying principles that grant targeted and continuous drug delivery. Finally, future perspectives, and challenges for nanomicelles are discussed based on the current achievements and remaining issues.

Multiple Emitting Amphiphilic Conjugated Polythiophenes-Coated CdTe QDs for Picogram Detection of Trinitrophenol Explosive and Application Using Chitosan Film and Paper-Based Sensor Coupled with Smartphone.

Novel multiple emitting amphiphilic conjugated polythiophene-coated CdTe quantum dots for picogram level determination of the 2,4,6-trinitrophenol (TNP) explosive are developed. Four biocompatible sensors, cationic polythiophene nanohybrids (CPTQDs), nonionic polythiophene nanohybrids (NPTQDs), anionic polythiophene nanohybrids (APTQDs), and thiophene copolymer nanohybrids (TCPQDs), are designed using an in situ polymerization method, which shows highly enhanced fluorescence intensity and quantum yield (up to 78%). All sensors are investigated for nitroexplosive detection to provide a remarkable fluorescence quenching for TNP and the quenching efficiency reached 96% in the case of TCPQDs. The fluorescence of the sensors are quenched by TNP through inner filter effect, electrostatic, π-π, and hydrogen bonding interactions. Under optimal conditions, the detection limits of CPTQDs, NPTQDs, APTQDs, and TCPQDs are 2.56, 7.23, 4.12, and 0.56 × 10-9 m, respectively, within 60 s. More importantly, portable, cost effective, and simple to use paper strips and chitosan film are successfully applied to visually detect as little as 2.29 pg of TNP. The possibility of utilizing a smartphone with a color-scanning APP in the determination of TNP is also established. Moreover, the practical application of the developed sensors for TNP detection in tap and river water samples is described with satisfactory recoveries of 98.02-107.50%.

Phospholipase A2-Responsive Phosphate Micelle-Loaded UCNPs for Bioimaging of Prostate Cancer Cells.

We report the effective synthesis of biocompatible upconversion nanoparticles (UCNP)-loaded phosphate micelles and successful delivery of UCNPs to prostate cancer cells via secreted phospholipase A2 (sPLA-2) enzyme cleavage of the loaded micelles for the first time. The activity of the (sPLA-2) enzyme toward the synthesized micelles was investigated and confirmed by LC-MS. TEM results showed that the micelles have a size distribution of 80 to 150 nm, whereas UCNP-loaded micelles range from 200 to 350 nm, indicating the successful loading of UCNPs. The selective release of UCNPs to prostate cancer cells rather than other cells, specifically cervical cancer cells, was observed and confirmed by a range of bioimaging studies. Moreover, cytotoxicity assays confirmed the biocompatibility of the UCNP-loaded micelles.

Preparation and characterization of chitosan-clay nanocomposites for the removal of Cu(II) from aqueous solution.

In the present study, chitosan assembled on gold and silver nanoparticles were prepared and characterized by UV-vis, TEM, EDX and DLS techniques. The nanocomposites chitosan (Ch)/clay, chitosan (Ch)/AgNPs/clay and chitosan (Ch)/AuNPs/clay were prepared by solution mixing method and characterized by FTIR, XRD, and SEM techniques. The adsorption of copper(II) ions onto the prepared hybrid composites from an aqueous solution using batch adsorption was examined. The results showed that benefiting from the surface property of clay, the abundant amino and hydroxyl functional groups of chitosan, the adsorbent provides adequate and versatile adsorption for the Cu(II) ions under investigation. The batch adsorption experiments showed that the adsorption of the Cu(II) is considerably dependent on pH of milieu, the amount of adsorbent, and contact time. Batch adsorption studies revealed that the adsorption capacity of Cu(II) increased with increase in initial concentration and contact time with optimum pH in the range around neutral. The maximum uptake of Cu(II) ions by (Ch)/AgNPs/clay composite was found to be 181.5mg/g. The adsorption efficiency of Cu(II) ions by prepared (Ch)/AgNPs/clay and (Ch)/AuNPs/clay is bigger than that the individual chitosan (Ch)/clay composite which clarifies the role of metal nanoparticles in enhancement the adsorption characters. The study suggests that the (Ch)/AgNPs/clay hybrid composite is a promising nano-adsorbent for the removal of Cu(II) ions from aqueous solution.

Synthesis and antimicrobial activity of polysaccharide alginate derived cationic surfactant-metal(II) complexes.

New natural polysaccharide carbohydrate derivatives of sodium alginate surfactant and its cobalt, copper and zinc complexes were synthesized. Structures of the synthesized compounds are reported using FTIR, (1)H NMR and UV-vis. The critical micelle concentration (CMC) value of the alginate surfactant and its metal complexes in aqueous solution was found out from surface tension measurements. Surface tension data at different temperatures served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔGmic, ΔHmic, ΔSmic) and adsorption (ΔGads, ΔGads, ΔSads). The surface activities of the synthesized polymeric surfactant and its metal complexes were influenced by their chemical structures and the type of the transition metals. These compounds were evaluated against Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and fungi (Candida albicans and Asperigllus niger). The antibacterial and antifungal screening tests of the alginate surfactant metal complexes have shown good results compared to its precursor alginate surfactant.

Synthesis, characterization and anticorrosion potentials of chitosan-g-PEG assembled on silver nanoparticles.

Chitosan (Ch) grafted with poly(ethylene glycol) (Ch-g-mPEG) were synthesized using mPEG with molecular weights 2000 g/mol. The synthesized Ch-g-mPEG was characterized using gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), and X-ray diffraction (XRD) techniques. Ch-g-mPEG silver nanoparticles has been synthesized and characterized by high-resolution transmission electron microscopy (HRTEM) and energy dispersive analysis of X-rays (EDAX). The synthesized Ch-g-mPEG and its nanostructure were examined as corrosion inhibitors for carbon steel in 1M HCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results revealed that the inhibition efficiency obtained by Ch-g-mPEG self-assembled on silver nanoparticles is greater than that obtained by Ch-g-mPEG only. Potentiodynamic polarization results reveal that the synthesized compound could be classified as mixed-type corrosion inhibitors with predominant control of the cathodic reaction. The results of EIS indicate that the both charge transfer resistance and inhibition efficiency tend to increase by increasing the inhibitor concentration.

Synthesis, surface properties and antimicrobial activity of some germanium nonionic surfactants.

Esterification reaction between different fatty acid namely; lauric, stearic, oleic and linoleic acids and polyethylene glycol-400 were performed. The produced polyethylene glycol ester were reacted with p-amine benzoic acid followed by condensation reaction with germanium dioxide in presence of sodium carbonate to form desired germinate surfactants. The chemical structures of the synthesized surfactants were determined using different spectra tools. The surface parameter including: the critical micelle concentration (CMC), effectiveness (π(cmc)), efficiency (Pc20), maximum surface excess (Γ(max)) and minimum surface area (A(min)), were calculated from the surface tension measurements. The synthesized surfactants showed higher surface activity. The thermodynamic parameters showed that adsorption and micellization processes are spontaneous. It is clear that the synthesized nonionic surfactants showed their tendency towards adsorption at the interfaces and also micellization in the bulk of their solutions. The synthesized surfactants were tested against different strain of bacteria using inhibition zone diameters. The synthesized surfactants showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative as well as fungi. The promising inhibition efficiency of these compounds against the sulfate reducing bacteria facilitates them to be applicable as new categories of sulfate reducing bacteria biocides.