Confocal Scanning Microscopy Research Articles

Virgin coconut and mustard oleogels as affected by beeswax and candelilla wax: functional, textural, rheological and morphological characteristics

SummaryEdible oleogels were developed using two oleogelators (beeswax and candelilla wax), at different concentrations of 6%, 9% and 12% w/w in virgin coconut and mustard oils using the direct dispersion method to study the techno‐functional characteristics. The different parameters including oil loss, temperature sweep tests, texture profiles and FT‐IR analysis demonstrated the formation of well‐structured oleogels with improved stability upon an increase in oleogelator concentrations. Crystal pattern exhibited by confocal scanning microscopy was majorly affected by the function of chemically distinct oils, more than the different oleogelators employed. It was found that the increase in smoke point was directly proportional to the level of oleogelator concentration in the oleogels, making them a suitable medium for frying. Intriguingly, on the basis of distinctive features, candelilla‐based oleogels were firmer with better and more stable crystals than beeswax‐based oleogels at the same level of concentration in both oils.

INNV-28. A PILOT STUDY EVALUATING THE FEASIBILITY OF USING AN ULTRA-FAST DIGITAL CONFOCAL MICROSCOPY SCANNER FOR REAL-TIME INTRA-OPERATIVE BRAIN TUMOUR DIAGNOSIS

Abstract INTRODUCTION Real-time intra-operative brain tumour tissue analysis in the operating room (OR) can shorten turnaround times and facilitate repeated sampling; the latter can improve diagnostic accuracy and guide resection to maximise extent. We evaluated the feasibility of using an ultra-fast confocal microscopy scanner (Histolog®, SamanTree Medical SA) in the OR for real-time intra-operative brain tumour tissue diagnosis. This study is the first use of Histolog® on primary human brain tissue globally. METHODS An observational pilot study with varying brain tumour types was conducted in a tertiary UK brain tumour centre. Multiple, freshly excised tissue samples were stained with Acridine Orange, and images captured within 60 seconds on Histolog® in the OR in parallel to current diagnostic pathways. A Consultant Neuropathologist performed a blinded correspondence assessment between Histolog® and current gold standard histopathology. Qualitative logging of diagnostic features was performed. RESULTS Cases studied (n=12) included glioma, metastasis, meningioma, schwannoma, and pituitary adenoma. Concordance between Histolog® and traditional (frozen section) intra-operative histopathological diagnosis was 83% (10/12 cases). One Histolog® case demonstrated superior diagnostic accuracy to frozen section. Histolog® images demonstrated specific diagnostic features such as clusters of cohesive epithelioid cells (metastatic carcinoma), sheet-like variably cellular and pleomorphic cells (gliomas), diffuse sheet-like monomorphic round nuclei (pituitary adenoma), elongated spindle cells (schwannoma), and nodular architecture and oval nuclei (meningioma). DISCUSSION Ultra-fast confocal microscopy scanning with Histolog® is feasible in the OR and Histolog® image resolution is adequate to identify histopathological features necessary for intra-operative brain tumour diagnosis. Training and clinico-radiological details are important in minimising discordance. A larger study with greater numbers and tumour types will now be performed to define an optimal scanning protocol and determine the strengths and limitations of the technology. Future studies should investigate the effect of real-time margin zone analysis on extending resection.

Abstract 13187: Inhibition of Advanced Glycation End Products Formation and Serum Protein Infiltration in Bioprosthetic Heart Valves: Investigations of Anti-Glycation Agents

Introduction: Bioprosthetic heart valves (BHV) fabricated from glutaraldehyde pretreated bovine pericardium (BP), are the most commonly used heart valve replacements. However, BHV durability is limited by structural valve degeneration (SVD) resulting from both calcification and advanced glycation end product (AGE) deposition together with serum protein infiltration. This study investigated, for the first time, the application of anti-glycation agents as a way to mitigate AGE-related structural degeneration of BHV. Hypothesis: We investigated the hypothesis that anti-AGE agents (Aminoguanidine (AG), Pyridoxamine (PYR), and N-Acetylcysteine (NAC)) could mitigate BP glycation in model studies, both in vitro and in vivo. Methods: To model AGE accumulation in BHV, we used well-established accelerated in vitro glycation models using BP incubation with or without inhibitors. Incorporation of AGE in BP was monitored using radiolabeled glycation precursors. Changes in collagen structure were examined by two photon confocal microscopy and differential scanning calorimetry. In vivo studies used a juvenile rat subdermal BP implantation model with drug administration via drinking water. Endpoints were AGE formation, collagen structure, thermal denaturation temperature, serum albumin uptake, calcification, and serum glycation marker levels. Results: In vitro studies demonstrated that each of these agents significantly inhibited AGE formation in BP. However, after 28-day rat subdermal BP implantation in vivo, only PYR demonstrated significant inhibition of both AGE and serum albumin accumulation per immunostaining. BHV calcification was not mitigated by PYR, AG or NAC. Conclusions: This study is the first to demonstrate the use of AGE inhibitors in mitigating BHV glycation. PYR demonstrated significant efficacy both in vitro and in vivo, mitigating AGE formation and albumin infiltration in BP. Thus, this study provides a rationale for investigating PYR as a possible candidate for improving the durability and biocompatibility of clinically used BHV, providing the solution for this unmet clinical need.

Диагностика синдрома лимбальной недостаточности

Relevance. Limbal stem cell deficiency (LSCD) is a pathology that leads to substantial vision decrease, corneal neovascularization, corneal epithelial persistent erosions and have a negative impact on patient's the quality of life. It is known that the efficiency of corneal transplantation in LSCD patients is low and requires repeated interventions. One of the important problems is the lack of a clear diagnostic algorithm and a standardized set of diagnostic techniques for this condition. Purpose. Systematically analyze domestic and foreign literature on the currently existing methods for diagnosing LSCD. Material and methods. A systematic analysis of scientific publications from 1992 to 2021 was carried out. Its included domestic and foreign authors on the resources of PubMed, Medline, eLibrary, as well as dissertations and textbooks devoted to currently existing methods for diagnosing LSCD. Results. In addition to biomicroscopy, the main in vivomethods for diagnosing LSCD are staining of the ocular surface, impression cytology with the detection of specific cytokeratins, confocal microscopy, optical coherence tomography of the anterior segment (OST) and OST-angiography. Conclusion. Physician awareness and vigilance are required for the diagnosis of LSCD, especially in patients with conjunctivalization and corneal neovascularization. It is impossible to use only biomicroscopy and the patient's complaints, since LSCD is not always obvious. That is why diagnostics should include an integrated approach, including all available research methods, which are briefly described in Table No. 1 with their disadvantages and advantages. Key words: limbal stem cell deficiency, impression cytology, laser confocal scanning microscopy, goblet cells, cytokeratin, penetrating keratoplasty, cytokines

Prolonged Inhibition of Streptococcus mutans Growth and Biofilm Formation by Sustained Release of Chlorhexidine from Varnish Coated Dental Abutments: An in Vitro Study.

Background It has been confirmed that bacterial biofilm covering dental implants is the main microbial source causing preimplant infectious and inflammatory diseases. The purpose of this study was to evaluate the antibacterial/antibiofilm effect of chlorhexidine, incorporated into a sustained-release varnish of chlorhexidine (SRV-CHX) coating, on dental abutments. Materials and Methods Three kinds of dental abutments were used: a high-performance semi-crystalline engineering thermoplastic polyetheretherketone (PEAK) healing abutment, a titanium healing abutment, and a titanium permanent abutment. These abutments were coated with SRV-CHX or SRV-placebo and exposed daily to fresh cultures of Streptococcus mutans. The effect of SRV-CHX on S. mutans growth on agar plates was studied by measuring the zone of inhibition (ZOI) around each tested abutment every day for a period of 36 days. Biofilm formation on the SRV-CHX/placebo-coated abutments was detected using confocal laser scanning microscopy (CLSM) and high-resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), and monitored by crystal violet (CV) staining. Results SRV-CHX-coated abutments 2 and 3 were able to inhibit S. mutans growth for 34 days, while abutment 1 inhibited growth for 32 days. Abutment-associated biofilm formation was notably inhibited by SRV-CHX coating after 13 days of incubation with S. mutans. Finally, the biofilm formed around SRV-CHX-coated abutments was completely inhibited up to 12 days of abutment exposure to S. mutans. Conclusion Coating of dental abutments with SRV-CHX demonstrated long-term effective inhibition of S. mutans growth and biofilm formation on the abutment surface.

Guaiacol augments quorum quenching potential of ciprofloxacin against Pseudomonas aeruginosa.

The present study aims to investigate the antimicrobial as well as antivirulence potential and the principle mechanism of action of guaiacol against Pseudomonas aeruginosa. Quorum sensing inhibition and membrane disruption studies were performed to check the effect of guaiacol on the virulence of P. aeruginosa. Production of various virulence factors and biofilm formation was studied at a sub-MIC concentration of guaiacol alone (1/8 MIC) and in combination with ciprofloxacin (1/2 FIC). Guaiacol exhibited synergistic interactions with ciprofloxacin and further reduced the production of all virulence factors and biofilm formation. Using crystal violet (CV) assay and quantification of exopolysaccharide, we observed weak biofilm formation, together with reduced motilities at sub-MIC, which was further visualized by confocal laser microscopy and Field Emission Scanning Electron Microscopy. The antibacterial activity of guaiacol against P. aeruginosa upon 2 × MIC exposure coincided with enhanced membrane permeability leading to disruption and release of cellular material as quantified by CV uptake assay and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The results demonstrated that sub-MICs of guaiacol in combination with ciprofloxacin can act as a potent alternate compound for attenuation of quorum sensing in P. aeruginosa. The study reports that guaiacol in combination with ciprofloxacin at 1/2 FIC significantly compromised the bacterial growth and motilities alongside inducing quorum quenching potential. This was accompanied by inhibition of biofilm which subsequently decreased EPS production at sub-MIC concentration. Furthermore, guaiacol in combination displayed a severe detrimental effect on bacterial membrane disruption, thereby enhancing cellular material release. For the first time, the potential of guaiacol in combination with ciprofloxacin in attenuation of virulence factors, and biofilm formation in Pseudomonas aeruginosa was described. Results corroborate how plant bioactive in synergism with antibiotics can act as an alternate treatment regime to tackle the menace of drug resistance.

Response of soybean (Glycine max L.) seedlings to polystyrene nanoplastics: Physiological, biochemical, and molecular perspectives

Micro and nanoplastics are new generation contaminants of global concern. It is important to evaluate the effects on edible products due to the presence of micro- and nano-sized plastics in the treated wastewater. A hydroponic experiment was carried out to explore the effect of polsytrene nanoplastics (PS-NPs; 20 nm) at different concentrations (0, 12.5, 25, and 50 mg L−1) on Glycine max L. (soybean) seedlings for 7-days. In the current study, firstly the uptake of PS-NPs by Glycine max L. (soybean) roots were confirmed by laser confocal scanning microscope. Exposure to PS-NPs, negatively affected growth parameters and increased Fe, Zn and Mn contents in roots and leaves of soybean seedlings. PS-NPs treatments caused oxidative stress in soybean seedlings. The hydrogen peroxide and malondialdehyde contents, showed similar increase pattern in seedlings exposed to PS-NPs. Response to PS-NPs, the level of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and guaiacol peroxidase) and proline content were generally enhanced in roots and leaves of soybean. The expression level of stress-related genes examined in the study included CSD5, FSD3, APX1, and POD up-regulated in PS-NPs treated-soybean seedlings in a tissue specific manner. The results of the present study showed the adverse effects of PS-NPs on soybean seedlings, which may have important implications for the risk assessment of NPs on crop production and environmental safety.

Antioxidant and anti-aging effects of polysaccharide LDP-1 from wild <em>Lactarius deliciosus</em> on <em>Caenorhabditis elegans</em>

Background: Edible fungi (mushrooms) have attracted much more concerns due to their abundant nutritions and functional bioactive substances like polysaccharides.
 Objective: In this study, the anti-oxidation and anti-aging activities of polysaccharide fraction (LDP-1) from the wild Lactarius deliciosus fruiting bodies were systematically evaluated using Caenorhabditis elegans (C. elegans) as a model.
 Methods: Lifetime determination of C. elegans (survival status) was observed via microscope. Effects of LDP-1 on C. elegans induced by heat and oxidative stress were, respectively, performed in an artificial climate chamber and Juglone solution. Determination of lipofuscin levels in C. elegans was observed by laser confocal scanning microscopy. Determination of reactive oxygen species in C. elegans in vivo was conducted via fluorescence spectrophotometer reader.
 Results: The results revealed that LDP-1 could significantly extend the lifespan of C. elegans, and the lifetime of C. elegans treated with 1,000 μg/mL LDP-1 could be prolonged by 32.8% compared with the control. The survival rates of the experimental C. elegans under heat shock and oxidative stress conditions were clearly improved after treated with 1,000 μg/mL LDP-1 (40 and 19.8%, respectively), while under the same circumstances all the C. elegans in the blank group died. Fluorescence microscopy analysis confirmed that LDP-1 could effectively reduce the accumulation of lipofuscin and reactive oxygen free radicals in C. elegans, where the respective maximum reduction reached 22.8 and 42.7% compared with the control.
 Conclusion: These results indicate that LDP-1 had favorable antioxidant and anti-aging effects, which could be explored as potential dietary additives to renovate oxidative damage and slow down aging process.

Preparation and corrosion resistance of epoxy resin coating for bonded NdFeB magnet

The epoxy resin (ER) coatings were coated on ring-shaped bonded NdFeB magnet (RSM) using air spraying and cathodic electrophoresis deposition processes. The morphologies and microstructures of the bare RSM (B-RSM), sprayed ER/RSM (S-ER/RSM) and electrophoretic ER/RSM (E-ER/RSM) were observed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), 3D laser confocal scanning microscopy (LSCM) and fourier infrared spectrometer (FTIR). The corrosion behaviors of the ER coatings were analyzed by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and neutral salt spray test (NSS). The results showed that ER coatings covered the pores of B-RSM well and played a good sealing role. Moreover, E-ER/RSM had a more uniform film layer and better surface leveling than S-ER/RSM. Compared with B-RSM and S-ER/RSM, the corrosion current density (Icorr) of E-ER/RSM reached 1.904 × 10−5 A/cm2, one order of magnitude lower than that of B-RSM (1.033 × 10−4 A/cm2) and about twice lower than that of S-ER/RSM (4.728 × 10−5 A/cm2). The value of charge transfer resistance (Rct) of E-ER/RSM is 1671.6 Ω·cm2, which is higher than that of both B-RSM (236.96 Ω·cm2) and S-ER/RSM (425.46 Ω·cm2). The NSS time of E-ER/RSM reached 144 h, longer than that of S-ER/RSM (72 h) and B-RSM (24 h). The corrosion resistance of bonded NdFeB magnets was improved due to the good shielding properties and physical barrier effect of the ER coatings. In addition, the corrosion mechanisms of ER coatings were discussed in detail.

Preparation and Properties of Fluorosilicone Fouling-Release Coatings.

To improve the antifouling performance of silicone fouling-release coatings, some fluorosilicone and silicone fouling-release coatings were prepared and cured at room temperature with hydroxyl-terminated fluoropolysiloxane (FPS) or hydroxy-terminated polydimethylsiloxane (PDMS) as a film-forming resin, tetraethyl orthosilicate (TEOS) as a crosslinking agent, and dibutyltin dilaurate (DBTDL) as a catalyst. The chemical structure, surface morphology and roughness, tensile properties, and antifouling properties of the coating were studied by infrared spectroscopy, a laser confocal scanning microscope, contact angle measurement, tensile tests, and marine bacteria and benthic diatom attachment tests. The results showed that the FPS coatings were not only hydrophobic but also oleophobic, and the contact angles of the FPS coatings were larger than those of the PDMS coatings. The surface free energies of the FPS coatings were much lower than those of the PDMS coatings. Generally, the fluorine groups can improve the antifouling performance of the coating. Introducing nonreactive silicone oil into PDMS or FPS coatings can improve the antifouling performance of the coating to a certain extent. The prepared fluorosilicone fouling-release coatings showed good application prospects.

Fructus mume Aqueous Extract's Antibacterial Effect on Multi-species Biofilm

Aim: The purpose of this study was to determine the efficacy of several irrigants and an aqueous extract of Fructus mume in eradicating three kinds of biofilm. Materials and Methods: A three-species biofilm of E. faecalis, P. gingivalis and F. nucleatum were cultivated for one week on Thermanox™ plates. Each specimen was immersed for 8 minutes in various irrigants: Fructus mume solution, buffered citric acid, sodium hypochlorite and control (non-irrigated). LIVE/DEAD® BacLightTM staining and confocal light scanning microscopy were used to determine the number of viable bacteria left on the substrate. The same biofilm was then extracted and subjected to scanning electron microscopy (SEM). Results: Images were taken at 12 locations across the biofilm, which were then classified into four areas of concern: Bottom, which would spend the most of the experiment submerged in the solution; It was struck in the centre by the stream of irrigant.; Middle and Upper, where the impression was caused by the irrigant splattering or vaporizing. Results of the amount of viable bacteria residual indicated that Fructus mume showed no significant activity, with an effect like control and even buffered citric acid, and significantly inferior to sodium hypochlorite. Conclusion: Sodium hypochlorite (0.5%) solution was greater to buffered citric acid, Fructus mume and control group as an antimicrobial agent against three-species biofilm.

A novel Pickering emulsion stabilized solely by hydrophobic agar microgels

A novel agar-based Pickering emulsion stabilizer was developed through the hydrophobic modification and microgelation of agar. After hexanoylation, the three-phase contact angle of hexanoylated agar (HAG) particles was adjusted from approximately 60° to 96° closing to neutral wettability. After microgelation, the particle size of the modified agar microgel was approximately 2 μm and Zeta potential reached −23.63 mV. Confocal laser microscopy and cryogenic scanning electron microscopy showed that HAG microgels formed a gel network or embedded on the surface of oil droplets, thus providing a dense barrier for oil droplets to coalesce and Ostwald ripening. The oil volume fraction and particle concentration had a significant effect on the droplet size and rheological properties of the Pickering emulsion. Pickering emulsion gels with long-term storage stability was prepared at low particle concentrations (0.7 wt%) and lower oil fractions (φ = 0.3– 0.5), which might become a new effective delivery system for bioactive substances.

JQ-1 ameliorates schistosomiasis liver granuloma in mice by suppressing male and female reproductive systems and egg development of Schistosoma japonicum.

Schistosomiasis is a serious and widespread parasitic disease caused by infection with Schistosoma. Because the parasite's eggs are primarily responsible for schistosomiasis dissemination and pathogenesis, inhibiting egg production is a potential approach to control the spread and severity of the disease. The bromodomain and extra-terminal (BET) proteins represent promising targets for the development of epigenetic drugs against Schistosoma. JQ-1 is a selective inhibitor of the BET protein family. In the present study, JQ-1 was applied to S. japonicum in vitro. By using laser confocal scanning microscopy and EdU incorporation assays, we showed that application of JQ-1 to worms in vitro affected egg laying and the development of both the male and female reproductive systems. JQ-1 also inhibited the expression of the reproductive-related genes SjPlk1 and SjNanos1 in S. japonicum. Mice infected with S. japonicum were treated with JQ-1 during egg granuloma formation. JQ-1 treatment significantly reduced the size of the liver granulomas and levels of serum alanine aminotransferase and aspartate aminotransferase in mice and suppressed both egg laying and the development of male and female S. japonicum reproductive systems in vivo. Moreover, the mRNA expression levels of some proinflammatory cytokines were decreased in the parasites. Our findings suggest that JQ-1 treatment attenuates S. japonicum egg-induced hepatic granuloma due at least in part to suppressing the development of the reproductive system and egg production of S. japonicum. These findings further suggest that JQ-1 or other BET inhibitors warrant additional study as a new approach for the treatment or prevention of schistosomiasis.

Effect of the microstructure on the corrosion behavior of dissimilar friction stir-welded 304 austenitic stainless steel and Q235 low-carbon steel joints

To investigate the effect of the microstructure on the corrosion behavior of the dissimilar friction stir welded (FSW) joint between 304 stainless steel (SS304) and Q235 low-carbon steel, the microstructure of the joint in this work was characterized by optical microscopy, scanning electron microscopy (SEM), and electron backscatter diffraction. The corrosion behavior in different zones of the joint was evaluated by the electrochemical tests, and the corresponding corrosion morphologies were illustrated via SEM and laser confocal scanning microscopy. According to the results, plenty of low-angle grain boundaries (LAGBs) and a low proportion of twin boundaries (TBs) deteriorated the corrosion resistance on the SS304 side of the joint. The corrosion products of the SS304 side mainly included γ-Fe2O3, FeCrO4, and Cr2O3, while those of the Q235 steel side were α-Fe2O3 and α-FeOOH. The corrosion mechanism in the stir zone (SZ) was galvanic corrosion between proeutectoid ferrite and pearlite on the Q235 steel side, during which the austenite remained uncorroded, whereas the proeutectoid ferrite, pearlite, and bainite were severely corroded. The above results indicated that the uniform distribution of mixed structures and a small area proportion of austenite (cathode) would improve the corrosion resistance in the SZ.

Novel Hyaluronic Acid ethosomes based gel formulation for topical use with reduced toxicity, better skin permeation, deposition, and improved pharmacodynamics

Hyaluronic Acid (HA) has been applied as an anti-ageing molecule in the form of topical products. Current topical commercial formulations of HA face the limitations of very small and stagnant skin permeation, thereby demanding enduring administration of the formulation to sustain its action. In this study, Lipid-based nanocarriers in the form of ethosomes were formulated in a 1% w/w HA strength and were extensively evaluated in vitro, ex-vivo, and in vivo parameters along with a comparison to it’s commercial counterpart. The optimised ethosomes-based HA gel formulation revealed required pH (6.9 ± 0.2), small globule size (1024 ± 9 nm), zeta potential of −6.39 ± 0.2 mV, and 98 ± 1.1% HA content. The ex vivo skin permeation and deposition potenwere conferred on synthetic membrane Strat-M, Human cadaver skin, mice skin, rat skin, and pig skin, and both parameters were found to be much higher in comparison to the commercial topical formulation. Skin deposition capacity of the optimised HA formulation was further confirmed by Scan Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) and it was observed that the developed ethosomal gel formulation got deposited more on the treated skin. The in vivo anti-ageing effect of optimised ethosomal gel on rats was found to be greater when compared to commercial formulation of HA and the developed carrier-based system proved to deliver the HA molecule in very small amounts into the systemic circulation. The results endorse the ethosomal carrier-based formulation of HA as a attractive technique for better local bioavailability of HA.

Non-Contact 3D Characterization System of Scratch-Induced Surface Damage on Monolithic Glass Panel

Glass material has been widely used in modern architecture. Scratch-induced surface damage of aged monolithic glass panel leads to the strength degradation of material and thus threatens the glass safety. Therefore, in order to accurately evaluate the strength of aged glass elements, it is crucial to extract key damage features including the damage location and depth in a precise way. This study aims to develop a non-contact stage-wise scanning method to extract 3D damage characteristics on glass surface, which can further facilitate the investigation into the associated influences on the flexural strength of glass. Coaxial double ring tests on annealed glass specimens under various magnitudes of applied loads were performed, which aimed to explore the influence of the surface damage on the flexural strength. Monocular microscope equipped with an industrial camera was used to detect damage area throughout the glass panel in the first stage rapidly. It was then followed by a chromatic confocal scanner to precisely measure the damage depth within local damage area. The results via confocal microscope scanning were considered as the reference values. It shows that the proposed method can be a potentially alternative solution instead of confocal microscope for damage quantification.

Effect of the properties of long afterglow phosphors on the antifouling performance of silicone fouling-release coating

To improve the static antifouling performance of the fouling-release silicone antifouling coating, blue-green (BG), yellow-green (YG), and sky blue (SB) long afterglow phosphors (LAP) with two kinds of luminescence intensities are added into the silicone coating, respectively, and the LAP/polydimethylsiloxane (PDMS) composite antifouling coating with different colors and luminance was prepared. Using a scanning electron microscope (SEM), X-ray diffractometer (XRD), laser particle size analyzer, and fluorescence spectrometer, the crystal structure, particle size, fluorescence properties, and emission wavelength of LAP were studied. Through laser confocal scanning microscope (CLSM), tensile test, contact angle measurement, photometer, marine bacteria, and boat-shaped benthic diatom attachment test, the surface morphology and roughness, tensile properties, wettability, and surface of the coating were studied energy, fluorescence illuminance, and anti-fouling performance. The results showed that the addition of LAP increased the fracture strength, elastic modulus, and surface free energy of the coatings. Each kind of LAP can improve the performance of PDMS coatings to inhibit the adhesion of marine bacterial biofilm and benthic marine algae. The higher the luminous illuminance, the better the antifouling performance of the coating. The SB coating has the most excellent antifouling performance and in particular, the relative adhesion rate (RAR) of fouling organisms of the SB highlight LAP/PDMS composite antifouling coating is only 37.8 %. This research provides new ideas for the development of new fluorescent antifouling coatings and has a certain enlightening significance for improving the static antifouling performance of fouling-release antifouling coatings (FRC).

Flocculation of quartz by a dual polymer system containing tannic acid and poly(ethylene oxide): Effect of polymer chemistry and hydrodynamic conditions

The flocculation behaviors of quartz using a dual polymer system containing tannic acid (TAN) and poly(ethylene oxide) (PEO) were investigated in this study, with dynamic floc size monitoring by the in-situ focused beam reflectance measurement technique. Variables of concern and their influence on the flocculation process were investigated from both physicochemical and hydrodynamic aspects, including solution pH, TAN/PEO ratio, and shear intensity. Floc structure was characterized using confocal scanning microscopy in suspension as well as freeze-drying-SEM imaging method. It was found that prior addition of TAN significantly increased the flocculation efficiency of quartz by PEO at neutral and alkaline pH, but not in acidic solutions despite that PEO induced the largest floc size at pH 3.1 when used alone. An optimal TAN/PEO ratio of 2 was observed for the best flocculation of quartz under the experimental conditions. Additionally, tannic acid could increase the strength of flocs formed by PEO, and the shear resistance of the flocs increased with increasing TAN/PEO ratio. The dual polymer system also contributed to the re-flocculation of quartz under cycled shear conditions, a phenomenon that was not observed when PEO was used alone. Zeta potential and adsorption density measurements confirmed that the pathway of the dual polymer flocculation was via the initial formation of TAN-PEO associative complexes in solution and then bridging of quartz by the associative complexes. The TAN-PEO associative complexes showed different structures and configurations at different pH, in line with a change in hydrogen bonding, which in turn affected floc structures and properties under turbulent conditions. This study helps to understand the improved flocculation, shear resistance and re-flocculation of fine particles induced by dual polymer system.

Antifungal effect of a new photosensitizer derived from BODIPY on Candida albicans biofilms

BackgroundPhotodynamic therapy (PDT) may be an alternative treatment of Candida albicans (C. albicans) infections. The aim of this study was to investigate the antifungal effect of PDT mediated by a new photosensitizer (PS) derived from BODIPY (BDP-4L) on C. albicans biofilms. MethodsC. albicans biofilms were incubated with BDP-4L of different concentrations and then irradiated at the light doses of 1.8, 3.6, 5.4, 7.2 and 9.0 J/cm2. XTT reduction assay was conducted to determine the PS concentration and PDT parameters. Confocal light scanning microscopy (CLSM) and scanning electron microscope (SEM) were used to visualize and quantify the effect of BDP-4L on C. albicans biofilms after PDT. ResultsC. albicans biofilms were inactivated in light dose-dependent and PS concentration-dependent manners using BDP-4L as PS. Without irradiation, no inactivation effect was observed when PS concentrations varied from 5 μM to 80 μM. 40 μM PS with 3.6 J/cm2 irradiation resulted in a significant reduction of 83.8% in biofilm metabolic activities. CLSM assay demonstrated that cell viability was obviously inhibited by 82.6%. SEM images revealed ruptured and rough cell surface, indicating increased cell membrane permeability after PDT. ConclusionsOur results suggested that BDP-4L mediated PDT exhibited a favorable antifungal effect on C. albicans biofilms.

Plasma Electroless Reduction: A Green Process for Designing Metallic Nanostructure Interfaces onto Polymeric Surfaces and 3D Scaffolds.

The design of metal nanoparticle-modified polymer surfaces in a green and scalable way is both desirable and highly challenging. Herein, a new green low-temperature plasma-based in situ surface reduction strategy termed plasma electroless reduction (PER) is reported for achieving in situ metallic nanostructuring on polymer surfaces. Proof of concept for this new method was first demonstrated on hydrophilic cellulose papers. Cellulose papers were dip-coated with different metal ion (Ag+ and Au3+) solutions and then subjected to hydrogen plasma treatment for this PER process. Transmission electron microscopy (TEM) analysis has revealed that this PER process caused anisotropic growth of either gold or silver nanoparticles, resulting in the time-dependent formation of both distinct spherical nanoparticles (∼20 nm) and anisotropic 2D nanosheets. Furthermore, we have demonstrated the adaptability of this process by applying it to hydrophobic fibrous and 3D printed polymeric materials such as surgical face masks and 3D printed polylactic acid scaffolds. The PER process on these hydrophobic polymer surfaces was accomplished via a sequential combination of air plasma and hydrogen plasma treatment. The metallic nanostructuring caused by the PER process on these hydrophobic surfaces was systematically studied using different surface imaging techniques including 3D confocal laser surface scanning microscopy and scanning electron microscopy. We have also systematically optimized the PER process on the surface of 3D scaffolds via varying the concentration of the silver ion precursor and by different postprocessing methods such as sonication and medium soaking. These optimization processes were found to be very important in generating uniform metallic nanoparticle-modified 3D printed scaffolds while simultaneously improving cytocompatibility. Through joint disk diffusion and inhibitory concentration testing, the antibacterial efficacy of silver coatings on face masks and 3D scaffolds was established. Altogether, these results clearly suggest the excellent futuristic potential of this new PER method for designing metallic nanostructured interfaces for different biomedical applications.