Glass Surface Research Articles

Programmed immobilization of living cells using independent click pairs

Therapeutic devices incorporating living cells or tissues have been intensively investigated for applications in tissue engineering and regenerative medicine. Because many biological processes are governed by spatially dependent signals, programmable immobilization of materials is crucial for manipulating multiple types of cells. In this study, click chemistry substrates were introduced onto the surfaces of cells and cover glass, and the cells were fixed on the cover glass via covalent bonds for selective cell deposition. Azide group (Az)-labeled living cells were prepared by metabolic labeling with azido sugars. Following the introduction of Az, TCO (trans-cyclooctene) was metabolically labeled into the living cells by reacting with TCO-DBCO (dibenzocyclooctyne). Az and TCO in the cells were detected using DBCO-FAM (fluorescein)and tetrazine-Cy3, respectively. The mixture of Az-labeled green fluorescent protein HeLa cells and TCO-labeled red fluorescent protein HeLa cells was reacted in a culture dish in which three different cover glasses, DBCO-, tetrazine-, or methyl-coated, were added. Az- or TCO-labeled cells could be immobilized in a functional group-dependent manner. Next, tetrazine-labeled cells were incubated on TCO- or Az-labeled cell layers instead of cover glass. Functional group-dependent immobilization was also achieved in the cell layer. Introducing substrates for the click reaction could achieve cell-selective immobilization on different patterned glass surfaces, as well as cell-cell immobilization.

Anti-fogging surfaces produced by plasma polymerization of acrylic acid

In this paper, plasma enhanced chemical vapor deposition (PECVD) of acrylic acid (AA) was employed as a one-step and solvent-free technique to prepare durable organic anti-fogging coatings on mirror and glass surfaces. The effects of important PECVD parameters including substrate temperature and plasma power on the deposition kinetics, as well as on the structural and morphological properties of the as-deposited films were investigated. Employing a low substrate temperature (5 °C) and a high plasma power (30 W) combination resulted in the highest observed deposition rate of 27.7 nm/min. Fourier-transform infrared (FTIR) spectroscopy showed high structural resemblance between PECVD-PAA and reference poly(acrylic acid) (PAA). The PAA-deposited surfaces showed excellent and durable anti-fogging performance without any loss in their optical transparencies. Successive antifogging tests showed that the PAA thin film exhibited high functional durability without delamination, indicating that it can be used in real-world applications.

Surface roughness characterization using representative elementary area (REA) analysis

We proposed the Representative Elementary Area (REA) analysis method and illustrated how it is needed to evaluate representative roughness parameters of surfaces. We used mean height (Sa) roughness to study how its variations converge to a steady state as we expanded the area of investigation (AOI) using combined scan tiles obtained through Confocal Laser Scanning Microscopy. We tested quartz and glass surfaces, subjecting them to various levels of polishing with grit sizes ranging between # 60 and #1200. The scan tiles revealed a multiscale roughness texture characterized by the dominance of valleys over peaks, lacking a fractal nature. REA analysis revealed Sa variations converged to a steady state as AOI increased, highlighting the necessity of the proposed method. The steady-state Sa, denoted as SaREA\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{Sa}}}_{{\ ext{REA}}}$$\\end{document}, followed an inverse power law with polishing grit size, with its exponent dependent on the material hardness. The REA length representing SaREA\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{Sa}}}_{{\ ext{REA}}}$$\\end{document} of glass surfaces, followed another inverse power law with polishing grit size and an indeterminate relationship for quartz surfaces. The multiscale characteristics and convergence to steady state were also evident in skewness, kurtosis, and autocorrelation length (Sal) parameters. Sal increased to a maximum value before decreasing linearly as AOI was linearly increased. The maximum Sal, termed as Salmax\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{Sal}}}_{{\ ext{max}}}$$\\end{document}, exhibited a linear relationship with REA. In the absence of REA analysis, the magnitude of uncertainty depended on the polishing grit size. Finely polished surfaces exhibited a 10–20% variability, which increased to up to 70% relative to the steady-state Sa with coarser polishing.

Method for Measuring the Three-Dimensional Morphology of Near-Wall Bubbles and Droplets Based on LED Digital Holography.

Digital holography, recognized for its noncontact nature and high precision in three-dimensional imaging, is effectively employed to measure the morphology of bubbles and droplets. However, in terms of near-wall bubbles and droplets, such as confined bubbles in microfluidic chips, the measurement of the interface morphology of bubbles near the glass surface has not yet been resolved due to the coherent noise resulting from glass surface reflections in microfluidic chips. Accordingly, an off-axis digital holography system was devised by using Linnik interferometry. Measuring the confined bubble interface near the wall within a microfluidic chip and droplet evaporation on solid surfaces was studied. Partially coherent LED sources and reference light modulation techniques were employed in the optical setup to mitigate the coherent noise. Dual exposure and weighted least-squares unwrapping algorithms were introduced to correct phase distortions, enhancing image quality. Imaging two confined CO2 bubbles was done near the wall in silicon oil within a porous microfluidic chip, and contact angles of 4.7 and 4.5° were measured. Additionally, the measurement of the three-dimensional morphology of vertically evaporating deionized water droplets on a glass surface was done, due to which calculation of contact angles at various orientations was possible. This work offers a feasible new method for measuring the 3D interface morphology of bubbles and droplets, particularly in microfluidic visualization, addressing current measurement gaps.

Electron irradiation-induced elements depletion and macroscopic changes in ternary borosilicate glasses: Mechanism and composition dependence

Glass, utilized for immobilizing high-level radioactive waste, experiences a decrease in mechanical properties and an increased risk of radioactive release after being exposed to β-radiation. A series of ternary borosilicate glasses were irradiated with 10 MeV electrons to doses ranging from 1 × 104 to 1 × 107 Gy. Nano-indentation, X-ray photoelectron spectroscopy, Time-of-Flight secondary ion mass spectrometry and Fourier-Transform infrared spectroscopy were used to characterize the glasses. After irradiation, the hardness of the glass decreased dramatically; the depletion of sodium, boron, oxygen and the enrichment of hydrogen, carbon in the glass surface were observed. The diffusion coefficients and depletion depths at different doses were fitted, both related to the composition of glass. With the absorbed dose increasing, Q0 ∼ Q2 transformed to Q3 and Q4, BO3 and BO4 decreased, molecular water and hydroxyl appeared. The formation of the depletion zone caused the reduction in hardness induced by irradiation. The glass showed phase separation characteristics. The mechanism and detailed process of element depletion were discussed. The composition dependence of depletion was explained based on the energy barrier model. The diffusion coefficient of elements depends on the activation energy of alkali.

Robust Gold Electrode Fabrication in a Microfluidic System

Electrode fabrication in microfluidic devices is often avoided due to the smaller footprint of the platform, associated complexity in the process, and absence of a well-established method. In this article a glass microchip with chemically modified and vapor deposited gold internal electrode was fabricated and used for biomolecule immobilization and electrochemical applications. The silanol (-OH) on glass surface of the microdevice was modified with (3-mercaptopropyl)trimethoxysilane prior to gold deposition to achieve a strong attachment of the metal film using the gold-thiol binding. The practical utility of the microdevice with gold surface was demonstrated by performing quantitative enzyme linked immunosorbent assay (ELISA) of human interferon gamma (IFN-γ) antigen, yielding a limit of detection (LOD) of 0.15 pg/mL compared to 4 pg/mL in the microplate assay. Additionally, the functionality of the internal electrode was established by performing cyclic voltammetry (CV) and linear sweep voltammetry (LSV) of potassium ferricyanide (III) in potassium chloride (KCl) solution using the proposed gold patterned electrode in the microchip, offering limits of detection of 0.14 and 0.11 mM for CV and LSV respectively. Both the ELISA and electrochemical assays were validated by generating calibration curves and using a control sample for the electroanalytical sensing applications. The measurements yielded experimental results that agreed with control concentration with 7% relative standard deviation (RSD). The promising reproducibility of the electrode in fabrication with no/minimum failure rate and its outstanding performance in immunosensor applications as well as an electron exchange surface makes our technique of gold electrode fabrication in microchips a state of the art.

The antimicrobial and antibiofilm potential of the Piper nigrum L. essential oil: in vitro, in situ, and in silico study

The modern era has raised awareness of healthier lifestyles and food safety, creating new goals for scientists and industry. Here, pathogen microorganisms represent one of the difficulties in ensuring food quality. Microorganism’s resistance to broad-spectrum antibiotics has increased, especially with the planktonic cells' ability to switch into sessile mode and form biofilms. In the endeavor for efficient natural food preservatives, essential oils represent one of the possible solutions for controlling food spoilage, due to their recognized antimicrobial properties. In this study, the assessment of the chemical profile of Piper nigrum L. essential oil (PNEO) was performed. The GC-MS analysis identified (E)-caryophyllene, limonene, and sabinene as prevalent constituents of PNEO, which prompted further antimicrobial and antibiofilm investigations. The minimal inhibitory concentration (MIC) assays revealed that PNEO generally expressed better antimicrobial properties in comparison to the common antibiotics. Moreover, the in situ antimicrobial analysis uncovered the ability of the PNEO’s vapor phase to inhibit the growth of L. monocytogenes, S. aureus, and H. influenzae on selected food models, exposing PNEO as a promising preservation agent. Antibiofilm effects of PNEO were evaluated against biofilm-forming P. fluorescens and S. maltophilia employing MIC assays, crystal violet assays, MALDI-TOF MS analysis, and molecular docking. The obtained results in MIC and crystal violet assays indicated significant antibiofilm activity of PNEO. The MALDI-TOF MS analysis revealed that PNEO altered the protein profiles of the investigated bacteria on stainless steel and glass surfaces, especially in the case of S. maltophilia. In silico antibiofilm investigations indicated a potential involvement of the PNEO components in the interference of quorum-sensing and drug-resistance mechanisms. These findings underline the antimicrobial and antibiofilm virtues of PNEO, indicating its promising usage in food preservation.

Atomic-scale planarization surface of quartz glass induced by novel green chemical mechanical polishing using three ingredients

Traditional chemical mechanical polishing (CMP) usually employs more than three kinds of toxic or corrosive ingredients for its slurry. Quartz glass is a hard-brittle solid, and it is extremely difficult to achieve its atomic-scale planarization surface. In these respects, it is a challenge to obtain atomic surface of quartz glass using green CMP slurry with three ingredients. To solve this challenge, a novel green CMP was developed, containing three green ingredients, such as ceria, sodium alginate and aminobutyric acid. After CMP, atomic surface is acquired with surface roughness Ra of 0.093 nm and material removal rate of 12.47 μm/h. Transmission electron microscopy confirms the thickness of damaged layer is 8.57 nm. X-ray photoelectron spectroscopy shows that –OH, C–N and –COOH groups adsorbed on the surface of quartz glass after immersion in CMP slurry, which agrees well with the simulated results of molecular dynamics. Density functional theory calculations reveal that electron transfer groups of aminobutyric acid and sodium alginate were predominantly located on –NH2 and –COOH, forming the covalent bonds between them. Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy indicate that new complexes were generated between aminobutyric acid and sodium alginate, increasing the viscosity of CMP slurry. Furthermore, the breakage of C–N and O–H bonds after CMP suggests that the complexes play a pivotal role in the CMP process. The developed novel green CMP with three ingredients provides new viewpoints to obtain atomic-scale planarization surface for a hard-brittle solid.

Design and Development of a Heating System to Control Windshield Fog

Road visibility in passenger vehicle is of major concern for the car manufacturers and safety design engineers. Water film (Fog) that forms on the windshield during winter times would reduce and disturb the driver’s visibility. Extreme weather condition can make a difference while driving. One may experience the wide range of challenges during driving. The factors which mostly affected the visibility can be rain, fog, ice, snow, dust, etc. Due to such factors, it becomes very tough for driver to have a clear view of front side. Rear view is possible with the help of left and right view mirror fitted outside the front doors. Visibility of rear view mirror depends upon the visibility of the front side window glasses. Driving through rain, produces more challenging situation when water droplets on outsides surface of front window glass obstruct the vision. This problem becomes more dangerous when light gets scattered through water droplets and obstruct the vision during rainy night. The main objective of this work is to find the possible solution for removing the fog from a specific area of front and rear windshield to have a clear view to avoid the accidents. In the present work, hot water and silicon fluid utilized to impinge on the front and rear glasses with the help of converging nozzle and fluid inside the two windshields. The various combination of outlet water and silicon temperature is used for obtaining maximum clearing area. Computer simulated results are verified with the experimental results.

Preparation and properties of hydrophobic materials based on environmentally responsive low fluorine epoxy copolymer

Hydrophobic surfaces and super hydrophobic surfaces have been widely studied and applied to cotton, ceramics, glass and other surfaces, but less research has been done on environmentally responsive hydrophobic surfaces (ERHS). In this paper, the environmentally responsive low fluorine epoxy copolymer P(DMAEMA-r-TFEMA-r-GMA) was synthesized by traditional free radical polymerization and the obtained copolymer was applied to construct ERHS on the cotton fabric and wood/plastic composite (WPC). The effects of construction parameters (polymer concentration, pH value of impregnation solution, impregnation temperature, impregnation time, drying temperature and drying time) on the surface hydrophobic properties of cotton fabric and WPC were studied. L25 (56) orthogonal experiment scheme was selected to explore the optimal parameters of hydrophobic construction. The optimum construction conditions of ERHS cotton and ERHS WPC were as follows: polymer concentration of 10 mg/mL, impregnation time of 9 h, pH of 9, impregnation temperature of 50 °C and 60 °C, drying time of 6 h, and drying temperature of 120 °C. The maximum water contact angle (WCA) on the surface of ERHS cotton was 145°. After 15 times pH-stimulation circulations, the WCA changed in the range of 145° ± 5° to 120° ± 5°. After 10 times acid-base response circulations, ERHS cotton had good oil-water separation capacity, and the maximum oil-water separation rate varied from 99.82% to 98.24%. This hydrophobic modification had no effect on the thermal stability of cotton fabric. The maximum WCA of ERHS WPC was 135°. Under acidic conditions (pH=2), the water absorption rate of wood plastic was improved. The hydrophobic modification had little effect on the mechanical properties and thermal stability of WPC.

Decoration of a Glass Surface with AgNPs Using Thio-Derivates for Environmental Applications

The aim of this study is to decorate a glass surface with silver nanoparticles (AgNPs) and further prove its efficiency in the removal of some thio-derivatives—potential pollutants from water. Therefore, grafting the surface of glass-based platforms with AgNPs will strongly influence their interaction with other substances or molecules. The most commonly used molecules for glass-based platform functionalization/modification are organosilanes. In this case, the main interest is in thioalkyl organosilanes because, after silanization, the thio (-SH) functional groups that have a high affinity for AgNPs can intermediate their binding on the surface. By decorating the glass platforms with AgNPs, these surfaces become active for the adsorption of dyes from wastewater. Certainly, in this case, the dyes must bear -SH groups to ensure a high affinity for these surfaces. Therefore, the desired purpose of this study was to develop glass-based platforms decorated with AgNPs able to bind model molecules—dyes from aqueous media (dithizone—DIT and thioindigo—TIO), with these platforms being potentially used for environmental applications.

The MATH test. A three-phase assay?

This study aimed to investigating the possible interference caused by glass test tubes on the quantification of bacterial adhesion to hydrocarbons by the MATH test. The adhesion of four bacteria to hexadecane and to glass test tubes was evaluated employing different suspending polar phases. The role of the ionic strength of the polar phase regarding adhesion to glassware was investigated. Within the conditions studied, Gram-positive bacteria adhered to both the test tube and the hydrocarbon regardless of the polar phase employed; meanwhile, Escherichia coli ATCC 25922 did not attach to either one. The capacity of the studied microorganisms to adhere to glassware was associated with their electron-donor properties. The ionic strength of the suspending media altered the patterns of adhesion to glass in a strain-specific manner by defining the magnitude of electrostatic repulsion observed between bacteria and the glass surface. This research demonstrated that glass test tubes may interact with suspended bacterial cells during the MATH test under specific conditions, which may lead to overestimating the percentage of adhesion to hydrocarbons and, thus, to erroneous values of cell surface hydrophobicity.

Organofunctionalization of silica from rice husk ash with ESIPT dyes

Excited-state intramolecular proton transfer (ESIPT) dyes were immobilized on amorphous silica obtained from rice husk ash through surface modification methodology. The silanol groups present on the surface of silica were first functionalized with isocyanate groups to be reacted with ESIPT dyes. Scanning electron microscopy, infrared spectroscopy, thermogravimetric, nitrogen adsorption/desorption, powder X-ray diffraction, and solid-state fluorescence emission spectroscopy analysis have been carried out to characterize the materials. The synthesized silica-based fluorescent materials were used as latent fingerprint developer powders present on glass surfaces. The results showed that latent fingerprints were revealed with high contrast under ultraviolet light illumination.

Suppression of Surface Crystallization of CaO-Al2O3-SiO2 Glass via Hydrothermal Treatment under Acidic Conditions.

This study demonstrates bulk crystallization of CaO-Al2O3-SiO2 (CAS) glass with suppression of surface crystallization via hydrothermal treatment under acidic conditions. It focuses on CAS glass-ceramics (GCs) with precipitated metastable CaAl2Si2O8, a layered calcium aluminosilicate, because it features a single bulk crystallization phase with a relatively lower volume fraction. After hydrothermal treatment under nitric acid, the resultant glasses possessed silica-rich surface layers. When the obtained glass with the surface layer was heat-treated at 1100 °C for 6 h, the resultant surface layer was easily peeled off by hand, and the cross section of both the edge and interior of the specimen showed precipitation of only metastable CaAl2Si2O8. The volume fraction of this crystalline phase was ∼50%, which was 20% larger than those reported for CAS GCs heat-treated at 1050 °C. By contrast, anorthite, the stable phase of CaAl2Si2O8, grew and invaded from the surface to the interior of the glass specimen heat-treated at 1100 °C for 6 h but not subjected to the hydrothermal treatment. These results indicate that the presence of a silica-rich layer on the glass surface suppressed surface crystallization even at the temperature that promotes surface crystallization, suggesting that the range of heat treatment conditions for glass crystallization can be expanded, enabling microstructural control of CAS GCs.

Surface-Enhanced Raman Spectroscopy Using a Silver Nanostar Substrate for Neonicotinoid Pesticides Detection.

Surface-enhanced Raman spectroscopy (SERS) has been introduced to detect pesticides at low concentrations and in complex matrices to help developing countries monitor pesticides to keep their concentrations at safe levels in food and the environment. SERS is a surface-sensitive technique that enhances the Raman signal of molecules absorbed on metal nanostructure surfaces and provides vibrational information for sample identification and quantitation. In this work, we report the use of silver nanostars (AgNs) as SERS-active elements to detect four neonicotinoid pesticides (thiacloprid, imidacloprid, thiamethoxam and nitenpyram). The SERS substrates were prepared with multiple depositions of the nanostars using a self-assembly approach to give a dense coverage of the AgNs on a glass surface, which ultimately increased the availability of the spikes needed for SERS activity. The SERS substrates developed in this work show very high sensitivity and excellent reproducibility. Our research opens an avenue for the development of portable, field-based pesticide sensors, which will be critical for the effective monitoring of these important but potentially dangerous chemicals.

Effect of 241Am buildup during spent fuel cooling on the decay heat of vitrified high-level waste and post-closure safety assessment

Long-term interim storage of spent fuel is a key factor affecting the thermal properties of vitrified high-level waste (HLW). In this study, we observed that increasing the spent fuel cooling-off period from 4 to 100 years decreased the decay heat of vitrified HLW and allowed a volume reduction of up to 13% based on the loading of the waste up to the thermal constraint of the repository. Contrastingly, the glass surface temperature 1000 years after disposal and the temperature-dependent glass dissolution rate increased with the cooling-off period due to 241Am buildup from 241Pu within that period. However, these dissolution rates can be regarded as nearly equivalent throughout the lifetime of glass dissolution because the glass temperature approached the host rock temperature and remained at this temperature for most of its lifetime. Consequently, the impact of 241Am buildup was confirmed to be negligible in the safety assessment of geological disposal with an intrinsically large safety margin.Graphical abstractPlots illustrating the effect of spent fuel cooling-off period on the thermal properties of vitrified high-level waste (HLW) and its long-term disposal safety. The left shows the results of waste volume reduction by higher waste loadings in the context of thermal constraint of the bentonite buffer less than 100 °C. The center shows the dissolution rate after disposal depending on the temperature of glass surface. The right is the result of safety assessment for different dissolution rates.

Insight into the inhibitory activity and mechanism of bovine cathelicidin BMAP 27 against Salmonella Typhimurium

This study synthesized an antimicrobial peptide based on the bovine cathelicidin BMAP 27 sequence. It was found to have a broad spectrum of antibacterial activity, with exceptionally high activity against Salmonella. However, the antibacterial mechanism of BMAP 27 against Salmonella remains unclear. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of BMAP 27 against Salmonella enterica serovar Typhimurium were determined to be 2 μM and 4 μM, respectively. After treatment with 2 MIC of BMAP 27, the absorbance of DNA in centrifugal supernatant increased from 0.244 to 1.464, and that of protein rose from 0.174 to 0.774, respectively. BMAP 27 has compromised the cell membrane as observed through field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM), and confirmed by the propidium iodide (PI) test. The alkaline phosphatase (AKP) enzyme activity in the supernatant of the 2 MIC treatment group was 2.15 times higher than the control group, indicating extracellular membrane damage. BMAP 27 treatment increased intracellular ROS levels as tested by dichlorofluorescein diacetate (DCFH) staining. DNA interaction analysis revealed that BMAP 27 has a binding affinity towards DNA, causing its characteristic bands to disappear and peak intensity at 260 nm to reduce. Molecular docking identified its potential binding mode with DNA. The crystal violet biofilm staining results demonstrated that BMAP 27 inhibited S. Typhimurium biofilm formation by 43.1 % and cleared mature biofilms by 53.62 %. Confocal Laser scanning electron microscopy (CLSM) observed that BMAP 27 could kill bacteria within the biofilm and dislodge bacteria from the surface of glasses. Swimming tests identified that the motor capacity of S. Typhimurium was diminished by BMAP 27. By counting the total bacteria, BMAP 27 was revealed to exert bacteriostatic effects in chilled pork and orange juice, which might provide a basis for its application in the inhibition of Salmonella.

Photocatalytic Reduction of VOCs with Ag/Ni-Doped Photocatalyst in Different Temperature and Humidity Environments

The photocatalytic oxidation (PCO) process is one of the most preferred, inexpensive, and environmentally friendly methods for VOC removal. It has been determined that this method can remove a wide range of organic pollutants. The removal of benzene and toluene pollutants, two important VOCs commonly encountered in flue gases, has been studied in the scope of this study using the photocatalytic oxidation method under UVA irradiation. For this purpose, the photocatalytic activity of the photocatalyst increased by the metal/metal doping process. Two different metals, a noble metal (Ag) and a transition metal (Ni), were used together for the doping of TiO2 nanoparticles, and the photocatalysts attached to a glass surface were prepared. Four different doping percentages were used for photocatalysts: 0.5%, 1%, 2.5%, and 5%. Several PCO experiments were conducted under different temperatures (120, 150, and 180 °C) and humidity conditions (25 and 50%). Photocatalytic oxidation experiments were carried out with artificially produced benzene and toluene gases, and the success of the system was evaluated with respect to removal efficiency calculations. The UVA light source was used for the photocatalytic experiments. The results of the study indicated that the removal efficiencies of toluene were found to be higher than those of benzene, and the most suitable conditions were determined to be 50% humidity and a 120 °C environment with the use of a 1% doped photocatalyst.

Embelia ribes Burm.f. fruit extract inhibit quorum sensing-dependent production of virulence factors and biofilm formation: An integrated in vitro and in silico approach

Quorum sensing (QS) is a cell-to-cell signaling method that allows bacteria to control gene expression and regulate a variety of physiological processes, particularly the synthesis of virulence factors and biofilm formation. Inhibition of QS has been proposed as a promising strategy in attenuating the pathogenicity and enhancing the efficacy of antimicrobial drugs targeting bacterial infections. This study investigated the potential utilization of Embelia ribes fruit extract (ERFE) as an inhibitor of QS-dependent virulence factors and biofilm development in Gram negative pathogens. Further, the results were correlated with the inhibition of biofilms. High performance thin-layer chromatography (HPTLC), followed by analysis of phytochemicals using gas chromatography-mass spectrometry (GC–MS) was conducted. Analyzing ADMET (absorption, distribution, metabolism, excretion and toxicity) profiles, PAINS (Pan-assay interference compounds), and molecular docking analyses of selected potential phytochemicals were performed against proteins participating in QS and formation of biofilm. In-vitro analysis of anti-QS activity of ERFE against Chromobacterium violaceum (violacein production), Pseudomonas aeruginosa (pyocyanin production) and Serratia marcescens (prodigiosin production) demonstrated significant dose-dependent interference in pigment formation at sub-MIC concentrations. The development of biofilm was significantly reduced by 84.10, 85.52 and 70.64% over control at the highest sub-MIC levels for C. violaceum, P. aeruginosa and S. marcescens, respectively. Furthermore, in the presence of ERFE, swarming motility and exopolysaccharide production (EPS) were also reduced. As a result, further insights have been gained into the mechanism underlying the anti-QS activity. Further investigations with in-vivo studies are warranted to fully explore the therapeutic applications of this natural compound in managing the bacterial pathogenicity and biofilm-related infections.

Enhancing the efficiency of lung cancer cell capture using microfluidic dielectrophoresis and aptamer-based surface modification.

Metastasis remains a significant cause to cancer-related mortality, underscoring the critical need for early detection and analysis of circulating tumor cells (CTCs). This study presents a novel microfluidic chip designed to efficiently capture A549 lung cancer cells by combining dielectrophoresis (DEP) and aptamer-based binding, thereby enhancing capture efficiency and specificity. The microchip features interdigitated electrodes made of indium-tin-oxide that generate a nonuniform electric field to manipulate CTCs. Following three chip design, scenarios were investigated: (A) bare glass surface, (B) glass modified with gold nanoparticles (AuNPs) only, and (C) glass modified with both AuNPs and aptamers. Experimental results demonstrate that AuNPs significantly enhance capture efficiency under DEP, with scenarios (B) and (C) exhibiting similar performance. Notably, scenario (C) stands out as aptamer-functionalized surfaces resisting fluid shear forces, achieving CTCs retention even after electric field deactivation. Additionally, an innovative reverse pumping method mitigates inlet clogging, enhancing experimental efficiency. This research offers valuable insights into optimizing surface modifications and understanding key factors influencing cell capture, contributing to the development of efficient cell manipulation techniques with potential applications in cancer research and personalized treatment options.