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The COVID-19 pandemic of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has over 750 million confirmed cases globally and more than six million deaths. Several variants have been named and identified as variants of concern by the World Health Organization (WHO); these include the Delta and Omicron variants. This work demonstrates the integration of epitope-imprinted conductive polymers with extended gate field effect transistors for the sensitive detection of the covid spike protein. Peptides from the receptor-binding domain on the spike protein were synthesized and imprinted onto poly(aniline-co-3-aminobenzenesulfonic acid), poly(AN-co-MSAN), by electropolymerization. Doping the conductive polymer film with titanium carbide (Ti2C) strengthened the electrochemical response approximately 1.5-fold. The FET platform not only amplified the electrochemical response about two-fold (compared with electrode-based sensing), but also lowered the sensing range for the SARS-CoV-2 spike protein subunit S1 (ncovS1) from 1.0 to 0.01 fg/mL.

Matrix metalloproteinase-1 (MMP-1) is associated with lung cancer, and thus the monitoring of the concentration of this protein may be useful for assessing lung cancer progression. In this work, poly(triphenylamine rhodanine-3-acetic acid-co-3,4-ethoxylene dioxy thiophene)s were incorporated onto a continuous monolayer (cML) of molybdenum disulfide (MoS2) by peptide-imprinted electropolymerization, in which peptides of MMP-1 were used as the templates in epitope imprinting. The morphology of the MoS2 thin film was monitored using optical and scanning electron microscopy. The imprinted MoS2 thin film electrode electrochemically responseded (at 1.0 pg/mL MMP-1) 1.4 times than ordinary imprinted electrodes. Moreover, MoS2 cML coating with PIPs can extend the sensing range of the PIP-coated electrodes from 1.0 pg/mL up to 10.0 pg/mL. The MoS2 cML electrode was used to determine that the MMP-1 concentration in the A549 cell line culture medium was 800 ng/mL. Comparison with results from a commercially available ELISA kit indicated an accuracy of 95 ± 5%.

Instead of molecularly imprinting a whole protein molecule, imprinting protein epitopes is gaining popularity due to cost and solubility issues. Belonging to the matrix metalloproteinase protein family, MMP-1 is an interstitial collagenase that degrades collagen and may be involved in cell migration, cell proliferation, the pro-inflammatory effect, and cancer progression. Hence, it can serve as a disease protein biomarker and thus be useful in early diagnosis. Herein, epitopes of MMP-1 were identified by screening its crystal structure. To identify possible epitopes for imprinting, MMP-1 was cleaved in silico with trypsin, pepsin at pH = 1.3, and pepsin at pH > 2.0 using Peptide Cutter, generating peptide fragments containing 8 to 12 amino acids. Five criteria were applied to select the peptides most suitable as potential epitopes for MMP-1. The triphenylamine rhodanine-3-acetic acid (TPARA) functional monomer was synthesized to form a stable pre-polymerization complex with a selected template epitope. The complexed functional monomer was then copolymerized with 3,4-ethoxylenedioxythiophene (EDOT) using potentiodynamic electropolymerization onto indium–tin–oxide (ITO) electrodes. The composition of the molecularly imprinted poly(TPARA-co-EDOT) (MIP) was optimized by maximizing the film’s electrical conductivity. Cyclic voltammetry was used to determine MMP-1 concentration in the presence of the Fe(CN)63−/Fe(CN)64− redox probe actuating the “gate effect.” A calibration curve was constructed and used to determine the usable concentration range and the limit of detection as ca. 0.001 to 10.0 pg/mL and 0.2 fg/mL MMP-1, respectively. Finally, the MMP-1 concentration in the A549 human lung (carcinoma) culture medium was measured, and this determination accuracy was confirmed using an ELISA assay.

To date, the increase in reactive oxygen species (ROS) production for effectual photodynamic therapy (PDT) treatment still remains challenging. In this study, a facile and effective approach is utilized to coat mesoporous silica (mSiO2) shell on the ligand-free upconversion nanoparticles (UCNPs) based on the LiYF4 host material. Two kinds of mesoporous silica-coated UCNPs (UCNP@mSiO2) that display green emission (doped with Ho3+) and red emission (doped with Er3+), respectively, were successfully synthesized and well characterized. Three photosensitizers (PSs), merocyanine 540 (MC 540), rose bengal (RB), and chlorin e6 (Ce6), with the function of absorption of green or red emission, were selected and loaded into the mSiO2 shell of both UCNP@mSiO2 nanomaterials. A comprehensive study for the three UCNP@mSiO2/PS donor/acceptor pairs was performed to investigate the efficacy of fluorescence resonance energy transfer (FRET), ROS generation, and in vitro PDT using a MCF-7 cell line. ROS generation detection showed that as compared to the oleate-capped and ligand-free UCNP/PS pairs, the UCNP@mSiO2/PS nanocarrier system demonstrated more pronounced ROS generation due to the UCNP@mSiO2 nanoparticles in close vicinity to PS molecules and a higher loading capacity of the photosensitizer. As a result, the three LiYF4 UCNP@mSiO2/PS nanoplatforms displayed more prominent therapeutic efficacies in PDT by using in vitro cytotoxicity tests.

C-reactive protein (CRP) is a non-specific biomarker of inflammation and may be associated with cardiovascular disease. In recent studies, systemic inflammatory responses have also been observed in cases of coronavirus disease 2019 (COVID-19). Molecularly imprinted polymers (MIPs) have been developed to replace natural antibodies with polymeric materials that have low cost and high stability and could thus be suitable for use in a home-care system. In this work, a MIP-based electrochemical sensing system for measuring CRP was developed. Such a system can be integrated with microfluidics and electronics for lab-on-a-chip technology. MIP composition was optimized using various imprinting template (CRP peptide) concentrations. Tungsten disulfide (WS2) was doped into the MIPs. Doping not only enhances the electrochemical response accompanying the recognition of the template molecules but also raises the top of the sensing range from 1.0 pg/mL to 1.0 ng/mL of the imprinted peptide. The calibration curve of the WS2-doped peptide-imprinted polymer-coated electrodes in the extended-gate field-effect transistor platform was obtained and used for the measurement of CRP concentration in real human serum.

A fluorescent probe for specific biorecognition was prepared by a facile method in which amphiphilic random copolymers were encapsulated with hydrophobic upconversion nanoparticles (UCNPs). This method quickly converted the hydrophobic UCNPs to hydrophilic UNCPs. Moreover, the self-folding ability of the amphiphilic copolymers allowed the formation of molecular imprinting polymers with template-shaped cavities. LiYF4:Yb3+/Tm3+@LiYF4:Yb3+ UCNP with up-conversion emission in the visible light region was prepared; this step was followed by the synthesis of an amphiphilic random copolymer, poly(methacrylate acid-co-octadecene) (poly(MAA-co-OD)). Combining the UCNPs and poly(MAA-co-OD) with the templates afforded a micelle-like structure. After removing the templates, UCNPs encapsulated with the molecularly imprinted polymer (MIP) (UCNPs@MIP) were obtained. The adsorption capacities of UCNPs@MIP bound with albumin and hemoglobin, respectively, were compared. The results showed that albumin was more easily bound to UCNPs@MIP than to hemoglobin because of the effect of protein conformation. The feasibility of using UCNPs@MIP as a fluorescent probe was also studied. The results showed that the fluorescence was quenched when hemoglobin was adsorbed on UCNPs@MIP; however, this was not observed for albumin. This fluorescence quenching is attributed to Förster resonance energy transfer (FRET) and overlap of the absorption spectrum of hemoglobin with the fluorescence spectrum of UCNPs@MIP. To our knowledge, the encapsulation approach for fabricating the UCNPs@MIP nanocomposite, which was further used as a fluorescent probe, might be the first report on specific biorecognition.

Herein, we successfully synthesized a series of LaF3:Yb3+/Er3+/Ho3+/Tm3+ upconversion nanoparticles (UCNPs) and LaF3:Yb3+0.20, Er3+0.02@LaF3:Yb3+0.20 core/shell UCNPs by modifying the amount of NaOH and the reaction time. Hexagonal LaF3 nanocrystals with uniform particle sizes and bright UC emissions were obtained. The crystal structures of the lanthanide-doped LaF3 UCNPs were investigated using wide-angle X-ray diffraction. The morphologies and particle sizes of the nanocrystals were determined using transmission electron microscopy. The photoluminescence (PL) spectra of the LaF3 nanocrystals could be tuned by altering the doping ratio of Er3+, Ho3+, and Tm3+. In addition, the PL intensities increased after coating the UCNP cores with an active shell. The fluorescence intensities of the UCNPs synthesized via a one-hour reaction with the addition of 2.5 or 5 mmol NaOH increased by up to 17 times compared with the sample prepared without the addition of NaOH. By modifying the doping ratio of Yb/Tm, UV-emissive LaF3 nanocrystals were obtained. After surface modification by ligand exchange, the hydrophobic LaF3:Yb3+0.20, Er3+0.02@LaF3:Yb3+0.20 core/shell UCNPs became water-dispersible. These colloid UCNPs could be utilized as a fluorescent probe for the detection of Hg2+ ions under 980 nm near-infrared irradiation.

Molecularly imprinted polymers (MIPs) can often bind target molecules with high selectivity and specificity. When used as MIPs, conductive polymers may have unique binding capabilities; they often contain aromatic rings and functional groups, which can undergo π－π and hydrogen bonding interactions with similarly structured target (or template) molecules. In this work, an electrochemical method was used to optimize the synthetic self-assembly of poly(aniline-co-metanilic acid) and testosterone, forming testosterone-imprinted electronically conductive polymers (TIECPs) on sensing electrodes. The linear sensing range for testosterone was from 0.1 to 100 pg/mL, and the limit of detection was as low as ~pM. Random urine samples were collected and diluted 1000-fold to measure testosterone concentration using the above TIECP sensors; results were compared with a commercial ARCHITECT ci 8200 system. The testosterone concentrations in the tested samples were in the range of 0.33 ± 0.09 to 9.13 ± 1.33 ng/mL. The mean accuracy of the TIECP-coated sensors was 90.3 ± 7.0%.

A photopolymerization method is used to prepare a mixture of polymer ionic liquid (PIL) and ionic liquid (IL). This mixture is used as a solid-state electrolyte in carbon nanoparticle (CNP)-based symmetric supercapacitors. The solid electrolyte is a binary mixture of a PIL and its corresponding IL. The PIL matrix is a cross-linked polyelectrolyte with an imidazole salt cation coupled with two anions of Br− in PIL-M-(Br) and TFSI− in PIL-M-(TFSI), respectively. The corresponding ionic liquids have imidazolium salt cation coupled with two anions of Br− and TFSI−, respectively. This study investigates the electrochemical characteristics of PILs and their corresponding IL mixtures used as a solid electrolyte in supercapacitors. Results show that a specific capacitance, maximum power density and energy density of 87 and 58 F·g−1, 40 and 48 kW·kg−1, and 107 and 59.9 Wh·kg−1 were achieved in supercapacitors based on (PIL-M-(Br)) and (PIL-M-(TFSI)) solid electrolytes, respectively.

In this work, we electrochemically deposited self-doped polyanilines (SPANI) on the surface of carbon-nanoparticle (CNP) film, enhancing the superficial faradic reactions in supercapacitors and thus improving their performance. SPANI was electrodeposited on the CNP-film employing electropolymerization of aniline (AN) and o-aminobenzene sulfonic acid (SAN) comonomers in solution. Here, SAN acts in dual roles of a self-doped monomer while it also provides an acidic environment which is suitable for electropolymerization. The performance of SPANI−CNP-based supercapacitors significantly depends upon the mole ratio of AN/SAN. Supercapacitor performance was investigated by using cyclic voltammetry (CV), galvanostatic charge and discharge (GCD), and electrochemical impedance spectroscopy (EIS). The optimal performance of SPANI−CNP-based supercapacitor exists at AN/SAN ratio of 1.0, having the specific capacitance of 273.3 Fg−1 at the charging current density of 0.5 Ag−1.

Organic-inorganic hybrid sols (Ti–O–Si precursor) were first synthesized by the sol-gel method at low addition of water, and were then employed to prepare a highly refractive hybrid optical film. This film was obtained by blending the Ti–O–Si precursor with 2-phenylphenoxyethyl acrylate (OPPEA) to perform photo-polymerization by ultraviolet (UV) irradiation. Results show that the film transparency of poly(Ti–O–Si precursor-co-OPPEA) film is higher than that of a pure poly(Ti–O–Si precursor) film, and that this poly(Ti–O–Si precursor-co-OPPEA) hybrid film exhibits a high transparency of ~93.7% coupled with a high refractive index (n) of 1.83 corresponding to a thickness of 2.59 μm.

The versatility of combining the immersing self-assembly and copolymerization techniques to build a well-defined, ultrathin, and continuous conducting Self-doped polyaniline (SPANI) interlayer on the indium tin oxide (ITO) surface as a first step in constructing a polymer light-emitting diode (PLED) is demonstrated. The conducting SPANI interlayer was found to enhance both carrier injection and electroluminescence efficiency, achieving a high LED brightness.

Melatonin levels may be related to the risks of breast cancer and prostate cancer. The measurement of urinary melatonin is also useful in monitoring serum melatonin levels following oral administration. In this work, melatonin is the target molecule, which is imprinted onto poly(ethylene-co-vinyl alcohol) by evaporation of the solvent on the working electrode of an electrochemical sensing chip. This sensing chip is used directly as a tool for optimizing the imprinting polymer composition, flow rate, and injection volume of the samples. Microfluidic sensing of the target and interference molecules revealed that the lowest detection limit is as low as ~pM, and the electrochemical response is weak even at high interference concentrations. Poly(ethylene-co-vinyl alcohol), containing 44 mol. % ethylene, had an imprinting effectiveness of more than six-fold. In random urine analysis, the microfluidic amperometric measurements of melatonin levels with an additional and recovery of melatonin, the melatonin recovery achieved 94.78 6 1.9% for melatonin at a concentration of 1.75-2.11 pg/mL. [ABSTRACT FROM AUTHOR]

Electrochemically oxidative copolymerizations on indium tin oxide electrode of aniline (AN) and o-aminobenzene sulfonic acid (OSA) with mole ratio of 25/75 in the presence of carbon nanotubes (CNT) and acid-treated CNT (fCNT) were conducted to investigate the electrocatalytic effects of the nanotubes on the copotymerizations. The P(25AN-co-75OSA)/CNT and P(25AN-co-75OSA)/fCNT composites were subsequently investigated into their electrocatalytic activities to the redox reactions of Fe(CN)63-/4- as a probe in aqueous solutions of different pH and detection capacities for dopamine (DA) and ascorbic acid (AA) by cyclic voltammetry. The results revealed that CNT and fCNT both electrocatalyzed the oxidations during the copolymerizations of P(25AN-co-75OSA), with CNT having a higher electrocatalytic capacity than fCNT. The so-prepared composites exhibited electrocatalytic activity for the redox reactions of Fe(CN)63-/4- in solutions of up to pH 7, with fCNT having a higher electrocatalytic activity than CNT. The P(25AN-co-75OSA)/fCNT composite film was able to detect DA and AA, exhibiting diffusion-controlled electron transfer rate. [ABSTRACT FROM AUTHOR]

Semi-crystalline poly(-lactic acid) (PLLA) was physically aged below the glass transition temperature for various times to investigate its amorphous phase behavior. During a differential scanning calorimetry heating scan, dual enthalpy recovery endotherms were found to appear in the glass transition region of PLLA, aged at 52 °C, of a particular degree of crystallinity ( X) within a definite range. Below the lower X limit, only the low endotherm corresponding to the free amorphous phase was observed; above the upper X limit, only the high endotherm corresponding to the constrained amorphous phase was observed. Dual tan δ peaks in dynamic mechanical analysis confirmed the coexistence of the dual amorphous phases. Both lower and upper limits of the X range increased with an increase in isothermal crystallization temperature from the melt. Long-term physical aging at 52 °C, which did not affect X, allowed the evolution of the free amorphous phase to the constrained amorphous phase in PLLA with X within the definite range. The effects of physical aging at various temperatures on the enthalpy recovery endotherms were also investigated. Copyright © 2011 Society of Chemical Industry The upper and lower crystallinity ( X) limits for producing dual amorphous phases in isothermally crystallized poly(-lactic acid) are a function of crystallization temperature ( T). [ABSTRACT FROM AUTHOR]

We incorporated hydroxyl groups into the polyurethane backbone and then used the "grafting to" approach to functionalize the multiwalled carbon nanotubes (MWNTs) via the esterification reaction between MWNTs and segmented polyurethanes (PUs). X-ray photoelectron spectroscopy (XPS) spectra showed that the sidewalls of MWNTs had been functionalized with acid treatment, and the amount of COOH increased with increasing acid treatment time. FTIR spectra further confirmed that PU was covalently attached to the sidewalls of MWNTs. The functionalized acid amount and the grafted PU amount were determined by thermogravimetric analyses (TGAs). Comparative studies based on SEM images of the PU-functionalized and chemically defunctionalized MWNT samples also revealed the covalent coating character. Dynamic mechanical analysis (DMA) of nanocomposite films prepared from PU and PU-functionalized MWNTs showed enhanced mechanical properties and increased soft segment Tg . Tensile properties indicated that PU-functionalized MWNTs were effective reinforcing fillers for the polyurethane matrix. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates visual fatigue and musculoskeletal discomfort of Chinese wheelchair users utilizing a VDT data entry task. The study gathered eight Chinese male wheelchair users to execute 9 different experimental combinations. Results revealed that visual fatigue and musculoskeletal discomfort is affected by the screen height and screen inclination.

Various blending ratios of chitosan/poly (vinyl alcohol) (CS/PVA) blend films were prepared by solution blend method in this study. The thermal properties and chemical structure characterization of the CS/PVA blend films were examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and Fourier transform infrared (FTIR). Based upon the observation on the DSC thermal analysis, the melting point of PVA is decreased when the amount of CS in the blend film is increased. The FTIR absorption characteristic is changed when the amount of CS in the blend film is varied. Results of X‐ray diffraction (XRD) analysis indicate that the intensity of diffraction peak at 19° of PVA becomes lower and broader with increasing the amount of CS in the CS/PVA blend film. This trend illustrates that the existence of CS decreases the crystallinity of PVA. Although both PVA and CS are hydrophilic biodegradable polymers, the results of water contact angle measurement are still shown as high as 68° and 83° for PVA and for CS films, respectively. A minimum water contact angle (56°) was observed when the blend film contains 50 wt % CS. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [ABSTRACT FROM AUTHOR]

Equilibrium tie line data have been determined at (323.15, 348.15, and 373.15) K for the ternary liquid−liquid equilibria (LLE) of three alkane hexylbenzene sulfolane systems, where the alkanes studied are decane, dodecane, and tetradecane. The relative mutual solubility of hexylbenzene is higher in decane sulfolane than in dodecane sulfolane or tetradecane sulfolane mixtures. The tie line data were correlated with the UNIQUAC and NRTL models. The calculated values based on the UNIQUAC model were found to be better than those based on the NRTL model. The values of selectivity and distribution coefficients were calculated from the equilibrium data. [ABSTRACT FROM AUTHOR]

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This study investigated the effect of keyboard height and inclination on musculoskeletal discomfort for wheelchair users. Eight Taiwanese male wheelchair users (28.75 ± 8.75 years) were recruited as participants to perform nine experimental combinations of data entry tasks. Three keyboard heights and three inclinations were evaluated. Musculoskeletal discomfort was estimated by Rating of Perceived Exertion and Subjective Preference Ranking. Each subject performed a data entry task for all nine experimental combinations in a random order. The seated posture of all participants during the data entry operation was the upright posture. The height of the screen's center was adjusted according to the eye level of each subject. Analysis showed the keyboard height and keyboard inclination significantly affected rating of musculoskeletal discomfort. It is suggested that the optimum keyboard height choice is el- bow-level height or 5 cm below elbow level with the keyboard inclination horizontal to the seat of the wheelchair. [ABSTRACT FROM AUTHOR]

The electrical transport properties of individual disordered multiwalled carbon nanotubes (MWCNTs), synthesized with the floating catalyst method, have been investigated. The resistivity of such disordered MWCNTs shows T1/2 dependence over a temperature range of 4.2–263 K. The experimental finding can be interpreted in terms of Al’tshuler-Aronov model [Solid State Commun. 30, 115 (1979); Sov. Phys. JETP 50, 968 (1979); Pis’ma. Zh. Eksp. Teor. Fiz. 27, 700 (1978)], in which strong electron-electron interaction leads to a Coulomb gap in the density of electronic states at the Fermi level. Such a wide fitting range of temperature for T1/2 dependence has never been reported for other materials, implying an extremely short carrier scattering time of the order of femtoseconds. [ABSTRACT FROM AUTHOR]

Terbium aluminum garnet (TAG) was successfully synthesized by a solid-state reaction method in this study. Before calcining, the mixing powder of terbium oxide (TbO7), boehmite (AlOOH), and cerium chloride (CeCl3∙7H2O) was aged at pH 1, 2, and 3, respectively. Experimental results revealed that the better process for the formation of TAG powder was aged at pH 1. The effects of pH on the formation of TAG powder were further studied. The diffusion distance between terbium oxide and boehmite was reduced by aging the mixed slurry at pH 1. A pure phase of TAG powder was obtained after the aged mixture of boehmite, terbium oxide, and cerium chloride was heated at 1200°C for 2 h and then calcined at 1500°C for 20 h. The particle size of pure TAG powders is the agglomerate morphology through scanning electron microscopy observation. The formed TAG powder in this work had a maximum emission peak in 553 rim as exciting at 470 nm. [ABSTRACT FROM AUTHOR]