Tunable Surface Wettability via Terahertz Electrowave Controlled Vicinal Subnanoscale Water Layer.

Achieving timely, reversible, and long-range remote tunability over surface wettability is highly demanded across diverse fields, including nanofluidic systems, drug delivery, and heterogeneous catalysis. Herein, using molecular dynamic simulations, we show, for the first time, a theoretical design of electrowetting to achieve remotely controllable surface wettability via using a terahertz wave. The key idea driving the design is the unique terahertz collective vibration identified in the vicinal subnanoscale water layer, which is absent in bulk water, enabling efficient energy transfer from the terahertz wave to the rotational motion of the vicinal subnanoscale water layer. Consequently, a frequency-specific alternating terahertz electric field near the critical strength can significantly affect the local hydrogen-bonding network of the contact water layer on the solid surface, thereby achieving tunable surface wettability.

GIWAXS experimental methods at the NFPS-BL17B beamline at Shanghai Synchrotron Radiation Facility.

The BL17B beamline at the Shanghai Synchrotron Radiation Facility was first designed as a versatile high-throughput protein crystallography beamline and one of five beamlines affiliated to the National Facility for Protein Science in Shanghai. It was officially opened to users in July 2015. As a bending magnet beamline, BL17B has the advantages of high photon flux, brightness, energy resolution and continuous adjustable energy between 5 and 23 keV. The experimental station excels in crystal screening and structure determination, providing cost-effective routine experimental services to numerous users. Given the interdisciplinary and green energy research demands, BL17B beamline has undergone optimization, expanded its range of experimental methods and enhanced sample environments for a more user-friendly testing mode. These methods include single-crystal X-ray diffraction, powder crystal X-ray diffraction, wide-angle X-ray scattering, grazing-incidence wide-angle X-ray scattering (GIWAXS), and fully scattered atom pair distribution function analysis, covering structure detection from crystalline to amorphous states. This paper primarily presents the performance of the BL17B beamline and the application of the GIWAXS methodology at the beamline in the field of perovskite materials.

Fluorescent immunochromatographic test strip for therapeutic drug monitoring of methotrexate with high sensitivity and wide dynamic range.

As a front-line chemotherapeutic drug for maintenance and consolidation therapy, methotrexate (MTX) has widely been applied to treat various tumors and some inflammatory diseases. However, because of its severe toxicity ascribed to low selectivity, it is necessary to monitor therapeutic drugs in high-dose MTX therapeutic regimens to ensure treatment safety. In this work, we developed a fluorescent immunochromatographic test strip (FITS) for monitoring MTX by employing time-resolved fluorescent microspheres as signal probes. With a competitive immunoassay mode, the FITS for MTX shows a super-wide dynamic range of 10 pM-10 µM, covering the entire clinical therapeutic concentration range of MTX. Therapeutic drug monitoring of MTX can be achieved within 7 min with high specificity, facilitating the timely rescue of drug poisoning led by high-dose MTX treatment. The method was employed for monitoring MTX in the spiked human serum, urine, and milk, showing acceptable recoveries ranging from 94.0 to 110.0%. The established FITS has been applied to MTX detection in serum obtained from high-dose MTX treatment. The results from FITS and enzyme multiplied immunoassay technique showed no significant difference, suggesting its reliability for usage in real biological samples. The device shows promise in point-of-care therapeutic drug monitoring for resource-limited countries and institutes, which significantly facilitates overcoming the lag time between sampling and results.

Compact plasmon modulator with a high extinction ratio.

To keep pace with the demands in optical communications, electro-optic modulators should feature a high extinction ratio, offer a small footprint, and allow for practical detection. Herein, we demonstrate a compact plasmon modulator with a high extinction ratio where a compact modulation region composed of indium tin oxide (ITO) is embedded to the arms of the Mach-Zehnder (M-Z) interferometer. The modulator has a footprint of 20µm×12µm with a modulation region of 4µm×0.5µm. The numerical results show that the extinction ratio is 15.2 dB when the electron concentration of ITO is changed 4×1020cm-3. This type of modulator paves the way for future compact optoelectronic integration and has potential application in the fields of optical communication, photodetection, and sensing.

Broadband terahertz signatures and vibrations of dopamine.

Dopamine (DA) is an essential neurotransmitter and hormone of the nervous system, its structural and conformational properties play critical roles in biological functions and signal transmission processes. Although this neuroactive molecule has been studied extensively, the low-frequency vibration features that are closely related to the conformation and molecular interactions in the terahertz (THz) band still remain unclear. In this study, a broadband THz time-domain spectroscopy (THz-TDS) system in the frequency band of 0.5-18 THz was used to characterize the unique THz fingerprint of DA. In addition, density functional theory (DFT) calculations were performed to analyze the vibrational properties of DA. The results suggest that each THz resonant absorption peak of DA corresponds to specific vibrational modes, and the collective vibration also exists in the broadband THz range. Moreover, the interactions between the DA ligand and the D2 and D3 receptors were investigated by docking, and the simulated THz spectra were obtained. The results indicate the dominant role of hydrogen bonding interactions and the specificity of molecular conformation. This work may help to understand the resonance coupling between THz electromagnetic waves and neurotransmitters.

Probing NaCl hydrate formation from aqueous solutions by terahertz time-domain spectroscopy.

The cooling-induced formation of a hydrate in aqueous NaCl solutions was probed using terahertz time-domain spectroscopy (THz-TDS). It was found that the NaCl hydrate formation is accompanied by the emergence of four new absorption peaks at 1.60, 2.43, 3.34 and 3.78 THz. Combining X-ray diffraction measurements with solid-state based density functional theory (DFT) calculations, we assign the observed terahertz absorption peaks to the vibrational modes of the formed NaCl·2H2O hydrate during cooling. This work shows that THz-TDS based analysis has great potential in studying ionic hydrates and the newly revealed collective vibrational modes could be sensitive indicators to achieve quantitative analysis in phase transitions and lattice dynamics.

Characteristic fingerprint spectrum of neurotransmitter norepinephrine with broadband terahertz time-domain spectroscopy.

The neurotransmitter norepinephrine (NE) was investigated by broadband terahertz time-domain spectroscopy (THz-TDS) in the air-plasma system range from 0.5 to 18.2 THz. NE has a unique absorption spectrum in the THz band, which can be used as a characteristic fingerprint for molecular detection and identification. The temperature-dependent THz spectra of NE were recorded in the range from 83 to 293 K, and a blue-shift of the absorption peaks was observed as the temperature decreased. A solid-state density functional theory (DFT) calculation was implemented to better understand the low-frequency vibrational property of NE, and the calculated results agree well with the THz experimental observations. This result suggests that the broadband THz system can obtain more abundant spectral signals of NE and each THz resonance peak has its own specific vibrational mode, which corresponds to a specific structure and interaction. Even with the adjacent absorption peaks, the vibrational behaviors are different. The deformation of the aromatic ring and the flexibility of the side chain directly affect the NE molecular conformation, which may be closely associated with the receptor binding preference for the neurotransmitter. The conformational diversity of NE may help to understand the biological function of the neurotransmitter in the nervous system.

Synergistic antibacterial effect of tetracycline hydrochloride loaded functionalized graphene oxide nanostructures.

With the high demand for developing novel composites with integrated performance, graphene-based nanostructures have been drawing great attention in environmental and biomedical applications because of their extraordinary physicochemical properties and biocompatibility. Although graphene oxide (GO) nanosheets exhibit some antibacterial activities, novel GO based nanostructures with enhanced antibacterial activities are highly desired. To realize this aim, polyethyleneimine (PEI) modified GO as a tetracycline hydrochloride (TCH) carrier and release platform was constructed (pGO-TCH). The nanostructures were fully characterized by TEM, AFM, FTIR and Raman spectra, which demonstrated that TCH were uniformly and compactly deposited on PEI modified GO nanosheets. The antibacterial performances of the prepared nanostructures were investigated by disk diffusion method and bacterial growth kinetics method towards Gram-positive S. aureus and Gram-negative E. coli. Results show that pGO-TCH nanostructures exhibit good antibacterial behavior. The mechanism of antibacterial activity was studied. Moreover, the nanostructures showed good cytocompatibility. This study not only highlights a promising pGO-TCH nanostructure as a candidate of graphene-based antibacterial agent, but also provides us antibacterial mechanism between bacteria and graphene-based nanomaterials.

Monitoring cis-to-trans isomerization of azobenzene using terahertz time-domain spectroscopy.

We present terahertz time-domain spectroscopy (THz-TDS) to explore the conformational dynamics of thermally induced and photoinduced isomerization of azobenzene. The essence of the method is that isomerization of azobenzene proceeds via large structural changes in the molecule, while the THz response is sensitive to these changes. We experimentally demonstrate that the THz spectra of azobenzene show remarkable variations upon heating and irradiation, and as such quantitatively recorded and identified THz spectroscopy can be used to monitor the isomerization process. Specifically, the measured THz spectra clearly reveal that the rate of thermal-isomerization from cis-to-trans in non-polar solvents is faster than that in polar solvents, and an about 6-fold acceleration of the rate could be achieved when Au NPs were introduced as a catalyst into azobenzenes. Moreover, we provide evidence that the temperature and Au NP catalyst do not have an obvious influence on the photoinduced isomerization of azobenzene. The presented example illustrates the power of the THz-TDS method to open up a novel avenue for exploring molecular dynamics.

Morphological, Release and Antibacterial Performances of Amoxicillin-Loaded Cellulose Aerogels.

Cellulose has been widely used in the biomedical field. In this study, novel cellulose aerogels were firstly prepared in a NaOH-based solvent system by a facile casting method. Then amoxicillin was successfully loaded into cellulose aerogels with different loadings. The morphology and structure of the cellulose aerogels were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The drug release and antibacterial activities were also evaluated. The drug release results showed that cellulose aerogels have controlled amoxicillin release performance. In vitro antibacterial assay demonstrated that the cellulose aerogels exhibited excellent antibacterial activity with the amoxicillin dose-dependent activity. Therefore, the developed cellulose aerogels display controlled release behavior and efficient antibacterial performance, thus confirming their potential for biomedical applications.

Evaporation-induced self-assembly of Janus pyramid molecules from fractal network to core-shell nanoclusters evidenced by small-angle X-ray scattering.

Self-assembly of nanoclusters (NCs) is an effective synthetic method for preparing functionalized nanomaterials. However, the assembly process and mechanisms in solutions still remain ambiguous owing to the limited strategies to monitor intermediate assembled states. Herein, the self-assembly process of amphiphilic molecule 4POSS-DL-POM (consisting of four polyhedral oligomeric silsesquioxanes, a dendritic linker, and one polyoxometalate) by evaporation of acetone in a mixed acetone/n-decane solution is monitored by time-resolved synchrotron small-angle X-ray scattering (SAXS). Scattering data assessments, including Kratky analysis, pair distance distribution function, and model fitting, track the self-assembly process of 4POSS-DL-POM from a fractal network to compact NCs, then to core-shell NCs, and finally to superlattice structure. The calculated average aggregation number of a core-shell NC is 11 according to the parameters obtained from core-shell model fitting, in agreement with electron microscopy. The fundamental understanding of the self-assembly dynamics from heterocluster into NCs provides principles to control building block shape and guide target aggregation, which can further promote the design and construction of highly ordered cluster-assembled functional nanomaterials.

Upgrade of crystallography beamline BL19U1 at the Shanghai Synchrotron Radiation Facility.

BL19U1, an energy-tunable protein complex crystallography beamline at the Shanghai Synchrotron Radiation Facility, has emerged as one of the most productive MX beamlines since opening to the public in July 2015. As of October 2023, it has contributed to over 2000 protein structures deposited in the Protein Data Bank (PDB), resulting in the publication of more than 1000 scientific papers. In response to increasing interest in structure-based drug design utilizing X-ray crystallography for fragment library screening, enhancements have been implemented in both hardware and data collection systems on the beamline to optimize efficiency. Hardware upgrades include the transition from MD2 to MD2S for the diffractometer, alongside the installation of a humidity controller featuring a rapid nozzle exchanger. This allows users to opt for either low-temperature or room-temperature data collection modes. The control system has been upgraded from Blu-Ice to MXCuBE3, which supports website-mode data collection, providing enhanced compatibility and easy expansion with new features. An automated data processing pipeline has also been developed to offer users real-time feedback on data quality.

Paper-based analytical device integrated with bacteriophage tail fiber protein for bacteria detection and antimicrobial susceptibility test.

Severe antimicrobial resistance calls for developing rapid, sensitive and affordable methodological platform for clinical diagnosis of bacterial infection. Herein, a paper-based analytical device (PAD) for fluorescent (FL) detection and antimicrobial susceptibility test (AST) of Pseudomonas aeruginosa (P. aeruginosa) was fabricated by defining 96 hydrophilic microzones on a filter paper using a handheld stamp dipped with liquid wax. The size of microzones was designed to be consistent with traditional 96-well microplate, thus the FL signals can be collected by a commercialized microplate reader. Streptavidin was immobilized into the microzones by chitosan-glutaraldehyde crosslinking reaction, and then biotinylated bacteriophage tail fiber protein (TFP) was conjugated through biotin-streptavidin affinity system. TFP and fluorescein isothiocyanate (FITC) labeled antimicrobial peptide were used as capture agent and signal probe, respectively, for FL detection of P. aeruginosa on the PAD. The linear range for quantifying P. aeruginosa is 1.0 × 103 CFU/mL to 1.0 × 107 CFU/mL, with a detection limit of 137 CFU/mL. The PAD was also applied to conduct AST of P. aeruginosa for imipenem, meropenem, cefepime, amikacin, and gentamicin, and the results are consistent with the traditional broth dilution method. The PAD provides an affordable diagnosis platform for bacterial infection, especially in resource-limited institutes and countries.

The fingerprints of nifedipine/isonicotinamide cocrystal polymorph studied by terahertz time-domain spectroscopy.

Cocrystal is constructed to improve physicochemical properties of active pharmaceutical ingredient and prevent polymorphism via intermolecular interactions. However, recent examples on cocrystal polymorphs display significantly different properties. Even though some analytical techniques have been used to characterize the cocrystal polymorphic system, it remains unclear how intermolecular interactions drive and stabilize the structure. In this work, we study the cocrystal polymorphs of nifedipine (NFD) and isonicotinamide (INA) using terahertz (THz) spectroscopy. Form I and form II of NFD-INA cocrystals show spectral fingerprints in THz region. Temperature-dependent THz spectra display distinguished frequency shifts of each fingerprint. Combined with solid-state density functional theory (DFT) calculations, the experimental fingerprints and their distinct responses to temperature are elucidated by specific collective vibrational modes. The vibrations of hydrogen bonding between dihydropyridine ring of NFD and INA are generally distributed below 1.5 THz, which play important roles in stabilizing cocrystal and preventing the oxidation of NFD. The rotations of methyl group in NFD are widely distributed in the range of 1.5-4.0 THz, which helps the steric recognition. The results demonstrate that THz spectroscopy is a sensitive tool to discriminate cocrystal polymorphs. It has the potential to be used as a non-invasive technique for pharmaceutical screening.

Sustainable, Highly Efficient and Superhydrophobic Fluorinated Silica Functionalized Chitosan Aerogel for Gravity-Driven Oil/Water Separation.

A superhydrophobic fluorinated silica functionalized chitosan (F-CS) aerogel is constructed and fabricated by a simple and sustainable method in this study in order to achieve highly efficient gravity-driven oil/water separation performance. The fluorinated silica functionalization invests the pristine hydrophilic chitosan (CS) aerogel with promising superhydrophobicity with a water contact angle of 151.9°. This novel F-CS aerogel possesses three-dimensional structure with high porosity as well as good chemical stability and mechanical compression property. Moreover, it also shows striking self-cleaning performance and great oil adsorption capacity. Most importantly, the as-prepared aerogels exhibits fast and efficient separation of oil/water mixture by the gravity driven process with high separation efficiency. These great performances render the prepared F-CS aerogel a good candidate for oil/water separation in practical industrial application.

A Double cross-linked strategy to construct graphene aerogels with highly efficient methylene blue adsorption performance.

A novel lysine and EDA double cross-linked graphene aerogel (LEGA) was constructed. The prepared LEGA was utilized as a methylene blue (MB) adsorbent in the wastewater treatment. It exhibits a three-dimensional interconnected porous structure benefiting dye adsorption. Its compression property is highly enhanced with the addition of lysine. Adsorption isotherm and kinetics of MB onto LEGA were discussed. Their results show that MB adsorption onto LEGA was fitted to follow Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. LEGA has an excellent adsorption capacity towards MB as high as 332.23 mg/g and its MB adsorption process is proved to be an exothermic process. The mechanism for MB adsorption onto LEGA was proposed as the ion exchange, electrostatic interaction, π-π stacking interaction and hydrogen bonding. Thus, LEGA is confirmed to be a sustainable and green MB adsorbent with highly removal efficiency in the treatment of wastewater.

Ultra-broadband terahertz fingerprint spectrum of melatonin with vibrational mode analysis.

Melatonin (MLT), as a neurotransmitter and an endogenous neurohormone, plays an important role in physiological functions through interactions with specific receptors. The conformations of MLT are closely related to its biological activities and functions. However, the internal relationship between the structure and interaction of MLT and its allosteric transition remains unclear. In this work, we obtain the broadband fingerprint terahertz (THz) spectrum of MLT in the range of 0.5-18 THz using the air-plasma terahertz time-domain spectroscopy (THz-TDS) system. DFT calculations are employed to analyze the vibration characteristics of MLT. The result shows that the low-frequency vibrations mainly come from the strong coupling between inter- and intramolecular vibrations, and the contribution of intramolecular vibrations gradually dominates with increasing frequency. Meanwhile, the local vibrations of the different functional groups distribute widely in the THz low-frequency band, relating to the diversity of conformational changes in the molecule. The intermolecular hydrogen bonds (HBs) have distinct resonant responses and play critical roles in the THz low-frequency vibrations. The study reveals the complex characteristics of the resonant coupling of MLT with THz electromagnetic waves. The results will help to understand the conformational preferences of MLT in neural signal transmission processes.

Probing lattice vibration of alkali halide crystals by broadband terahertz spectroscopy.

Terahertz spectral features of alkali halide crystals were studied with the combination of broadband terahertz time-domain spectroscopy and the solid-state-based density functional theory calculations. To understand the particular modes of the observed terahertz features of the alkali halide crystals, the resonant modes of KCl and CsCl were analyzed using face-centered cubic and body-centered cubic lattice models, respectively. The results show that the characteristic terahertz absorption peaks could be assigned to the lattice vibration of the ionic crystals. Furthermore, the terahertz responses of a series of alkali halides were recorded, and obvious absorption peaks were observed in each salt in the frequency region below 8.5 THz. What is more interestingly is that the frequencies of these observed peaks are red-shifted with the increases of the mass and radius of the ions. This correlation between the resonant frequency of the lattice vibration, the reduced atomic mass, and the equilibrium distance between the ions agrees well with the harmonic oscillator model.

Synthesis of Antibacterial Gelatin/Sodium Alginate Sponges and Their Antibacterial Activity.

In the present study, sponges with the antibiotic tetracycline hydrochloride (TCH) loaded into alginate incorporated with gelatin (G/SA) were fabricated. The G/SA sponges were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analysis. G/SA sponges show a three-dimensional network structure with high porosity. An excellent swelling behavior and a controlled TCH release performance are observed from G/SA sponges. Moreover, they exhibit good antibacterial activity against both Gram-positive and Gram-negative bacteria.

Antibacterial activity and long-term stable antibacterial performance of nisin grafted magnetic GO nanohybrids.

In this study, magnetic graphene oxide (MGO) nanohybrids were firstly fabricated by loading Fe3O4 NPs onto GO nanosheets and then novel nisin grafted MGO (nisin-g-MGO) nanohybrids were prepared by a facile method. The nisin-g-MGO nanohybrids exhibit strong enough magnetic separation capacity. The magnetic saturation (Ms) of nisin-g-MGO nanohybrids was 23.3 emu/g that enables nisin-g-MGO nanohybrids can be rapidly and completely separated from the black and stable suspension by an external magnet. The antibacterial studies of nisin-g-MGO nanohybrids show great antibacterial performance against Staphylococcus aureus and Bacillus subtilis, respectively. Moreover, the nisin-g-MGO nanohybrids exhibit long-term antibacterial stability that they still keep their good antibacterial activity after six months storage. Meanwhile, the fabricated nisin-g-MGO nanohybrids exhibit good biocompatibility without any obvious effect on HEK293 cell viability due to the calculated cell viabilities were more than 95%. And no observed changes in cell morphology were found in nisin-g-MGO nanohybrids treated HEK293 cells. Hence, the fabricated nisin-g-MGO nanohybrids exhibit great potentials in antibacterial application.