Pepsin immobilization on activated carbon and functionalized with glutaraldehyde and genipin for the synthesis of antioxidant peptides of goat casein.

In this article, the synthesis of antioxidant peptides in the enzymatic hydrolysis of caprine casein was analyzed at three different time points (60 min, 90 min, and 120 min) using immobilized pepsin on activated and modified carbon (AC, ACF, ACG 50, ACG 100). The immobilization assays revealed a reduction in the biocatalysts' activity compared to the free enzyme. Among the modified ones, ACG 50 exhibited greater activity and better efficiency for reuse cycles, with superior values after 60 min and 90 min. Peptide synthesis was observed under all studied conditions. Analyses (DPPH, ß-carotene/linoleic acid, FRAP) confirmed the antioxidant potential of the peptides generated by the immobilized enzyme. However, the immobilized enzyme in ACG 50 and ACG 100, combined with longer hydrolysis times, allowed the formation of peptides with an antioxidant capacity greater than or equivalent to those generated by the free enzyme, despite reduced enzymatic activity.

Double crosslinking decellularized bovine pericardium of dialdehyde chondroitin sulfate and zwitterionic copolymer for bioprosthetic heart valves with enhanced antithrombogenic, anti-inflammatory and anti-calcification properties.

Due to the increasing aging population and the advancements in transcatheter aortic valve replacement (TAVR), the use of bioprosthetic heart valves (BHVs) in patients diagnosed with valvular disease has increased substantially. Commercially available glutaraldehyde (GA) cross-linked biological valves suffer from reduced durability due to a combination of factors, including the high cell toxicity of GA, subacute thrombus, inflammation and calcification. In this study, oxidized chondroitin sulfate (OCS), a natural polysaccharide derivative, was used to replace GA to cross-link decellularized bovine pericardium (DBP), carrying out the first crosslinking of DBP to obtain OCS-BP. Subsequently, the zwitterion radical copolymerization system was introduced in situ to perform double cross-linking to obtain double crosslinked BHVs with biomimetic modification (P(APM/MPC)-OCS-BP). P(APM/MPC)-OCS-BP presented enhanced mechanical properties, collagen stability and enzymatic degradation resistance due to double crosslinking. The ex vivo AV-shunt assay and coagulation factors test suggested that P(APM/MPC)-OCS-BP exhibited excellent anticoagulant and antithrombotic properties due to the introduction of P(APM/MPC). P(APM/MPC)-OCS-BP also showed good HUVEC-cytocompatibility due to the substantial reduction of its residual aldehyde group. The subcutaneous implantation also demonstrated that P(APM/MPC)-OCS-BP showed a weak inflammatory response due to the anti-inflammatory effect of OCS. Finally, in vivo and in vitro results revealed that P(APM/MPC)-OCS-BP exhibited an excellent anti-calcification property. In a word, this simple cooperative crosslinking strategy provides a novel solution to obtain BHVs with good mechanical properties, and HUVEC-cytocompatibility, anti-coagulation, anti-inflammatory and anti-calcification properties. It might be a promising alternative to GA-fixed BP and exhibited good prospects in clinical applications.

Cyanophycin modifications for applications in tissue scaffolding.

Cyanophycin (CGP) is a polypeptide consisting of amino acids-aspartic acid in the backbone and arginine in the side chain. Owing to its resemblance to cell adhesive motifs in the body, it can be considered suitable for use in biomedical applications as a novel component to facilitate cell attachment and tissue regeneration. Although it has vast potential applications, starting with nutrition, through drug delivery and tissue engineering to the production of value-added chemicals and biomaterials, CGP has not been brought to the industry yet. To develop scaffolds using CGP powder produced by bacteria, its properties (e.g., biocompatibility, morphology, biodegradability, and mechanical strength) should be tailored in terms of the requirements of the targeted tissue. Crosslinking commonly stands for a primary modification method for renovating biomaterial features to these extents. Herein, we aimed to crosslink CGP for the first time and present a comparative study of different methods of CGP crosslinking including chemical, physical, and enzymatic methods by utilizing glutaraldehyde (GTA), UV exposure, genipin, 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS), and monoamine oxidase (MAO). Crosslinking efficacy varied among the samples crosslinked via the different crosslinking methods. All crosslinked CGP were non-cytotoxic to L929 cells, except for the groups with higher GTA concentrations. We conclude that CGP is a promising candidate for scaffolding purposes to be used as part of a composite with other biomaterials to maintain the integrity of scaffolds. The initiative study demonstrated the unknown characteristics of crosslinked CGP, even though its feasibility for biomedical applications should be confirmed by further examinations. KEY POINTS: • Cyanophycin was crosslinked by 5 different methods • Crosslinked cyanophycin is non-cytotoxic to L929 cells • Crosslinked cyanophycin is a promising new material for scaffolding purposes.

Removal of Cr(VI) by glutaraldehyde-crosslinked chitosan encapsulating microscale zero-valent iron: Synthesis, mechanism, and longevity.

Microscale zero-valent iron (mZVI) has shown great potential for groundwater Cr(VI) remediation. However, low Cr(VI) removal capacity caused by passivation restricted the wide use of mZVI. We prepared mZVI/GCS by encapsulating mZVI in a porous glutaraldehyde-crosslinked chitosan matrix, and the formation of the passivation layer was alleviated by reducing the contact between zero-valent iron particles. The average pore diameter of mZVI/GCS was 8.775 nm, which confirmed the mesoporous characteristic of this material. Results of batch experiments demonstrated that mZVI/GCS exhibited high Cr(VI) removal efficiency in a wide range of pH (2-10) and temperature (5-35°C). Common groundwater coexisting ions slightly affected mZVI/GCS. The material showed great reusability, and the average Cr(VI) removal efficiency was 90.41% during eight cycles. In this study, we also conducted kinetics and isotherms analysis. Pseudo-second-order model was the most matched kinetics model. The Cr(VI) adsorption process was fitted by both Langmuir and Freundlich isotherms models, and the maximum Langmuir adsorption capacity of mZVI/GCS reached 243.63 mg/g, which is higher than the adsorption capacities of materials reported in most of the previous studies. Notably, the column capacity for Cr(VI) removal of a mZVI/GCS-packed column was 6.4 times higher than that of a mZVI-packed column in a 50-day experiment. Therefore, mZVI/GCS with a porous structure effectively relieved passivation problems of mZVI and showed practical application prospects as groundwater Cr(VI) remediation material with practical application prospects.

Combined cross-linking of Rhizomucor miehei lipase and Candida antarctica lipase B for the effective enrichment of omega-3 fatty acids in fish oil.

The incorporation of a non-specific lipase and a sn-1,3 specific one in a single immobilized system can be a promising approach for the exploitation of both lipases. A one-step immobilization platform mediated by an isocyanide-based multi-component reaction was applied to create co-cross-linked enzymes (co-CLEs) of lipases from Rhizomucor miehei (sn-1,3 specific) and Candida antarctica (non-specific). Glutaraldehyde was found to be effective cross-linker by producing specific activity of 16.9 U/mg and immobilization yield of 99 %. High activity recovery of up to 404 % was obtained for immobilized derivatives. Leaking experiment showed covalent nature of the cross-linking processes. BSA had considerable effect on the immobilization process, providing 87-100 % immobilization yields and up to 10 times improvement in the specific activity of the immobilized derivatives. Scanning electron microscopy images showed flower-like and rod-like structures for the CLEs prepared by glutaraldehyde and undecanedicarboxylic acid, respectively. The prepared co-CLEs were examined in non-selective enrichment of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil, showing capability of releasing up to 100 % of both omega-3 fatty acids within 8 h of the reaction. The reusability of co-CLEs in five successive cycles presented retaining 63-72 % of their initial activities after the fifth reuse cycle in the hydrolysis reaction.

Immobilization of recombinant Trametes versicolor aflatoxin B1-degrading enzyme (TV-AFB1D) with montmorillonite for absorption and in situ degradation of aflatoxin B1.

Aflatoxin B1 is a highly carcinogenic and teratogenic substance mainly produced by toxin-producing strains such as Aspergillus flavus and Aspergillus parasitic. The efficient decomposition of aflatoxin is an important means to reduce its harm to humans and livestock. In this study, Trametes versicolor aflatoxin B1-degrading enzyme (TV-AFB1D) was recombinantly expressed in Bacillus subtilis (B. subtilis) 168. MMT-CTAB-AFB1D complex was prepared by the immobilization of TV-AFB1D and montmorillonite (MMT) by cross-linking glutaraldehyde. The results indicated that TV-AFB1D could recombinantly express in engineered B. subtilis 168 with a size of approximately 77 kDa. The immobilization efficiency of MMT-CTAB-AFB1D reached 98.63% when the concentration of glutaraldehyde was 5% (v/v). The relative activity of TV-AFB1D decreased to 72.36% after reusing for 10 times. The content of AFB1 in MMT-CTAB-AFB1D-AFB1 decreased to 1.1 µg/g from the initial 5.6 µg/g after incubation at 50 °C for 6 h. The amount of 80.4% AFB1 in the MMT-CTAB-AFB1D-AFB1 complex was degraded by in situ catalytic degradation. Thus, the strategy of combining adsorption and in situ degradation could effectively reduce the content of AFB1 residue in the MMT-CTAB-AFB1D complex.

Exploring sustainable food packaging: Nanocellulose composite films with enhanced mechanical strength, antibacterial performance, and biodegradability.

Food packaging films play a vital role in preserving and protecting food. However, due to their non-biodegradability, conventional packaging materials have led to significant environmental pollution. To overcome this hurdle, we have developed safe, innovative, sustainable and biodegradable packaging materials that can effectively extend the shelf life of food. In this study, two types of cellulose materials cellulose nanofibers (CNF) and carboxymethyl cellulose (CMC) with complementary roles were combined to prepare nanocellulose composite films with high transparency (90.3 %) of a certain thickness (30 ± 0.019 µm) by solution casting method, and their mechanical properties were further optimized by the addition of plasticizer-glycerol (Gly) and cross-linking agent-glutaraldehyde (GA), so as to maintain the strong tensile strength (≈112.60 MPa) and better malleability (4.12 %). In addition, we loaded the natural active agent tea polyphenols (TPs) with different concentrations to study the inhibition effect on E.coli and S.aureus and to simulate food packaging. Finally, we also found that the synthesized nanocellulose composite films can also achieve rapid degradation in a short time through soil burial, water flushing and immersion. The excellent performance demonstrated in this study provides reference value for further replacing petroleum-based materials with biomass materials in the field of food packaging.

SARS-CoV-2 inactivation in laboratory animal tissues with 4% formaldehyde or 5% glutaraldehyde for transfer to biosafety level 1 laboratories.

The SARS-CoV-2 pandemic required the immediate need to transfer inactivated tissue from biosafety level (BSL)-3 to BSL-1 areas to enable downstream analytical methods. No validated SARS-CoV-2 inactivation protocols were available for either formaldehyde (FA)-fixed or glutaraldehyde (GA)-fixed tissues. Therefore, representative tissue from ferrets and hamsters was spiked with 2.2 × 106 tissue culture infectious dose 50% per ml (TCID50/ml) SARS-CoV-2 or were obtained from mice experimentally infected with SARS-CoV-2. SARS-CoV-2 inactivation was demonstrated with 4% FA or 5% GA at room temperature for 72 hours by a titer reduction of up to 103.8 TCID50/ml in different animal tissues with a maximum protein content of 100 µg/mg and a thickness of up to 10 mm for FA and 8 mm for GA. Our protocols can be easily adapted for validating the inactivation of other pathogens to allow for the transfer of biological samples from BSL-3 areas to BSL-1 laboratories.

Use of glutaraldehyde-treated autologous pericardial patch in complete atrioventricular septal defect repair.

OBJECTIVE: Synthetic patch materials, such as polytetrafluoroethylene and knitted polyester, are commonly used for the repair of complete atrioventricular septal defects using the double-patch technique. In our study, we investigated the impact of glutaraldehyde-treated autologous pericardial patch on postoperative atrioventricular valve function. PATIENTS AND METHODS: In this retrospective study, patients who underwent repair of complete atrioventricular septal defects using the double-patch technique between January 1, 2018, and May 15, 2023, at our pediatric cardiac center were included in the study. Patients were divided into two groups based on the type of patch used for the repair of the ventricular component of the atrioventricular septal defect: autologous pericardial patch (group 1) and polytetrafluoroethylene patch (group 2). Postoperative data of the patients were retrospectively analyzed. RESULTS: Thirty-four patients (57.6%) were female, and 25 (42.4%) were male, with a median age of 7 (5-18) months. The median body weight at the time of surgery was 5.5 (4.1-10) kilograms. Down syndrome was present in 45 (76.3%) patients. The autologous pericardium was used for ventricular septal defect closure in 44 (74.6%) patients (Group 1), while polytetrafluoroethylene was used in 15 (25.4%) patients (Group 2). Permanent cardiac pacemaker placement was required in 4 (6.8%) patients due to postoperative atrioventricular block. Hospital mortality was 11.9% (n=7). Among these cases, 4 (6.8%) patients died from low cardiac output syndrome, and 3 (5.1%) patients died from sepsis. Postoperative echocardiographic evaluation revealed insignificant residual ventricular septal defects in 17 (28.8%) patients. No significant differences were observed between the groups in terms of mortality and postoperative atrioventricular valve insufficiency. The median follow-up duration for discharged patients was 5 months (7 days to 3.9 years). Throughout the follow-up period, there were no reoperations due to valve insufficiency or left ventricular outflow tract obstruction. CONCLUSIONS: Glutaraldehyde-treated autologous pericardium is a safe material that can be confidently used for the repair of the ventricular component of complete atrioventricular septal defects. This patch material does not adversely affect atrioventricular valve function and allows for the successful closure of ventricular septal defects.

Optimal treatment of tannic acid for the anti-calcification of bovine jugular veins and the underlying mechanism.

OBJECTIVES: To evaluate the effects of combined treatment with tannic acid and ferric ions on the biomechanical and anti-calcification properties of glutaraldehyde-fixed bovine jugular veins after xenografting. METHODS: Two-point bending test and uniaxial tensile test were used to evaluate the flexural and biomechanical properties; Subcutaneous implantation in rat and right ventricular outflow tract reconstruction of sheep were used to evaluate the anti-calcification effects; The performance of the graft in sheep models was evaluated every month after the surgery with echocardiography examination. Markers of macrophages, T lymphocytes, smooth muscle cell osteogenic differentiation and matrix metalloproteinases in sheep explants were detected by immunohistochemistry. RESULTS: The flexibility of the bovine jugular veins cotreated with ferric ions-tannic acid was improved while maintaining biomechanical properties and excellent anti-calcification effects. Echocardiography results showed that the grafts functioned well in the animals without stenosis or reflux of the valve. Immunohistochemical studies showed that the osteogenic differentiation marker (Runx2) was detected in calcified regions and colocalised with the SMC marker (α-SMA). Compared to the glutaraldehyde-treated samples, T-cell marker (CD3), matrix metalloproteinase-2 and 9 expressions were reduced in the ferric ions-tannic acid treated group. CONCLUSION: Ferric ions-tannic acid treatment can give the conduits better flexibility with excellent biomechanical properties and anti-calcification effects, making it a promising bovine jugular veins processing method.

A multifunctional bio-patch crosslinked with glutaraldehyde for enhanced mechanical performance, anti-coagulation properties, and anti-calcification properties.

Bio-patches for the treatment of valvular disease have been evaluated in clinical trials. It has been shown that failure of these devices, occurring within a few years of implantation, may be due to cytotoxicity, immune response, calcification and thrombosis. Some of these effects may be due to the glutaraldehyde crosslinking process used in the preparation of the materials. A number of studies have focused on strategies to control calcification, while others have concentrated on the prevention of micro-thrombus formation. In the present work, we have introduced amino-terminated poly(ethylene glycol) (NH2-PEG-NH2) as an intermolecular bridge, which not only eliminates free aldehyde groups to prevent calcification, but also introduces sites for the attachment of anticoagulant molecules. Furthermore, PEG, itself a hydrophilic polymer with good biocompatibility, may effectively prevent protein adsorption in the early stages of blood contact leading to thrombus formation. After further covalent attachment of heparin, modified bovine pericardium (BP) showed strong anti-calcification (calcium content: 39.3 ± 3.1 µg mg-1) and anti-coagulation properties (partial thromboplastin time: >300 s). The biocompatibility and mechanical properties, important for clinical use, were also improved by modification. The strategy used in this work includes new ideas and technologies for the improvement of valve products used in the clinic.

A synergistic strategy of dual-crosslinking and loading intelligent nanogels for enhancing anti-coagulation, pro-endothelialization and anti-calcification properties in bioprosthetic heart valves.

Currently, glutaraldehyde (GA)-crosslinked bioprosthetic heart valves (BHVs) still do not guarantee good biocompatibility and long-term effective durability for clinical application due to their subacute thrombus, inflammation, calcification, tearing and limited durability. In this study, double-modified xanthan gum (oxidized/vinylated xanthan gum (O2CXG)) was acquired from xanthan gum for subsequent double crosslinking and modification platform construction. Sulfonic acid groups with anticoagulant properties were also introduced through the free radical polymerization of vinyl sulfonate (VS) and vinyl on O2CXG. Taking advantage of the drug-loading function of xanthan gum, the treated pericardium was further loaded with inflammation-triggered dual drug-loaded nanogel (heparin (Hep) and atorvastatin (Ator)). Mechanical properties of O2CXG-crosslinked porcine pericardium (O2CXG-PP) were significantly improved via the first network formed by Schiff base bonds and the second C-C bonds network. Due to the presence of sulfonic acid groups as well as the dual drug release from nanogels under the stimulation of H2O2, the hemocompatibility, anti-inflammatory, pro-endothelialization and anti-calcification properties of the crosslinked pericardium modified with nanogels loaded with Hep and Ator (O2CXG+VS+(Hep+Ator) nanogel-PP) was significantly better than that of GA-crosslinked PP (GA-PP). The collaborative strategy of double crosslinking and sequential release of anticoagulant/endothelium-promoting drugs triggered by inflammation could effectively meet the requirement of enhanced multiple performance and long-term durability of bioprosthetic heart valves and provide a valuable pattern for multi-functionalization of blood contacting materials. STATEMENT OF SIGNIFICANCE: Currently, glutaraldehyde-crosslinked bioprosthetic heart valves (BHVs) are subject to subacute thrombus, inflammation, calcification and tearing, which would not guarantee good biocompatibility and long-term effective durability. We developed a cooperative strategy of double crosslinking and surface modification in which double-modified xanthan gum plays a cornerstone. The mechanical properties of this BHV were significantly improved via the first network formed by Schiff base bonds and the second C-C bonds network. Inflammation-triggered combination delivery of heparin and atorvastatin has been demonstrated to enhance anticoagulation, anti-inflammatory and pro-endothelialization of BHVs by utilizing local inflammatory response. The collaborative strategy could effectively meet the requirement of enhanced multiple performance and long-term durability of BHVs and provide a valuable pattern for the multi-functionalization of blood-contacting materials.

Postfunctionalization of biological valve leaflets with a polyphenol network and anticoagulant recombinant humanized type III collagen for improved anticoagulation and endothelialization.

Almost all commercial bioprosthetic heart valves (BHVs) are crosslinked with glutaraldehyde (GLUT); however, issues such as immune responses, calcification, delayed endothelialization, and especially severe thrombosis threaten the service lifespan of BHVs. Surface modification is expected to impart GLUT-crosslinked BHVs with versatility to optimize service performance. Here, a postfunctionalization strategy was established for GLUT-crosslinked BHVs, which were firstly modified with metal-phenolic networks (MPNs) to shield the exposed calcification site, and then anticoagulant recombinant humanized type III collagen (rhCOLIII) was immobilized to endow them with long-term antithrombogenicity and enhanced endothelialization properties. The postfunctionalization coating exhibited promising mechanical properties and resistance to enzymatic degradation capability resembling that of GLUT-crosslinked porcine pericardium (GLUT-PP). With the introduction of meticulously tailored rhCOLIII, the anti-coagulation and re-endothelialization properties of TA/Fe-rhCOLIII were significantly improved. Furthermore, the mild inflammatory response and reduced calcification were evidenced in TA/Fe-rhCOLIII by subcutaneous implantation. In conclusion, the efficacy of the proposed strategy combining anti-inflammatory MPNs and multifunctional rhCOLIII to improve anticoagulation, reduce the inflammatory response, and ultimately achieve rapid reendothelialization was supported by both ex vivo and in vivo experiments. Altogether, the current findings may provide a simple strategy for enhancing the service function of BHVs after implantation and show great potential in clinical applications.

Synthesis of Mesoporous Lanthanum-Doped SnO2 Spheres for Sensitive and Selective Detection of the Glutaraldehyde Disinfectant.

Glutaraldehyde disinfectant has been widely applied in aquaculture, farming, and medical treatment. Excessive concentrations of glutaraldehyde in the environment can lead to serious health hazards. Therefore, it is extremely important to develop high-performance glutaraldehyde sensors with low cost, high sensitivity, rapid response, fabulous selectivity, and low limit of detection. Herein, mesoporous lanthanum (La) doped SnO2 spheres with high specific surface area (52-59 m2 g-1), uniform mesopores (with a pore size concentrated at 5.7 nm), and highly crystalline frameworks are designed to fabricate highly sensitive gas sensors toward gaseous glutaraldehyde. The mesoporous lanthanum-doped SnO2 spheres exhibit excellent glutaraldehyde-sensing performance, including high response (13.5@10 ppm), rapid response time (28 s), and extremely low detection limit of 0.16 ppm. The excellent sensing performance is ascribed to the high specific surface area, high contents of chemisorbed oxygen species, and lanthanum doping. DFT calculations suggest that lanthanum doping in the SnO2 lattice can effectively improve the adsorption energy toward glutaraldehyde compared to pure SnO2 materials. Moreover, the fabricated gas sensors can effectively detect commercial glutaraldehyde disinfectants, indicating a potential application in aquaculture, farming, and medical treatment.

Avoiding scar tissue formation of peripheral nerves with the help of an acellular collagen matrix.

INTRODUCTION: Extensive scar tissue formation after peripheral nerve injury or surgery is a common problem. To avoid perineural scarring, implanting a mechanical barrier protecting the nerve from inflammation processes in the perineural environment has shown promising results for functional recovery. This study investigates the potential of an acellular collagen-elastin matrix wrapped around a peripheral nerve after induction of scar tissue formation. MATERIALS AND METHODS: In the present study, 30 Lewis rats were separated into three groups and sciatic nerve scarring was induced with 2.5% glutaraldehyde (GA-CM) or 2.5% glutaraldehyde with a supplemental FDA-approved acellular collagen-elastin matrix application (GA+CM). Additionally, a sham group was included for control. Nerve regeneration was assessed by functional analysis using the Visual Statisc Sciatic Index (SSI) and MR neurography during the 12-week regeneration period. Histological and histomorphometry analysis were performed to evaluate the degree of postoperative scar tissue formation. RESULTS: Histological analysis showed an extensive scar tissue formation for GA-CM. Connective tissue ratio was significantly (p < 0.009) reduced for GA+CM (1.347 ± 0.017) compared to GA-CM (1.518 ± 0.057). Similarly, compared to GA+CM, MR-Neurography revealed extensive scar tissue formation for GA-CM with a direct connection between nerve and paraneural environment. Distal to the injury site, quantitative analysis presented significantly higher axon density (p = 0.0145), thicker axon diameter (p = 0.0002) and thicker myelinated fiber thickness (p = 0.0008) for GA+CM compared to GA-CM. Evaluation of functional recovery revealed a significantly faster regeneration for GA+CM. CONCLUSION: The supplemental application of an acellular collagen-elastin matrix showed beneficial effects in histological, radiological, and functional analysis. Therefore, applying a collagen-elastin matrix around the nerve after peripheral nerve injury or surgery may have beneficial effects on preventing scar tissue formation in the long run. This represents a feasible approach to avoid scar tissue formation in peripheral nerve surgery.

A conventional fixation volume electron microscopy protocol for plants.

Volume electron microscopy techniques play an important role in plant research from understanding organelles and unicellular forms to developmental studies, environmental effects and microbial interactions with large plant structures, to name a few. Due to large air voids central vacuole, cell wall and waxy cuticle, many plant tissues pose challenges when trying to achieve high quality morphology, metal staining and adequate conductivity for high-resolution volume EM studies. Here, we applied a robust conventional chemical fixation strategy to address the special challenges of plant samples and suitable for, but not limited to, serial block-face and focused ion beam scanning electron microscopy. The chemistry of this protocol was modified from an approach developed for improved and uniform staining of large brain volumes. Briefly, primary fixation was in paraformaldehyde and glutaraldehyde with malachite green followed by secondary fixation with osmium tetroxide, potassium ferrocyanide, thiocarbohydrazide, osmium tetroxide and finally uranyl acetate and lead aspartate staining. Samples were then dehydrated in acetone with a propylene oxide transition and embedded in a hard formulation Quetol 651 resin. The samples were trimmed and mounted with silver epoxy, metal coated and imaged via serial block-face scanning electron microscopy and focal charge compensation for charge suppression. High-contrast plant tobacco and duckweed leaf cellular structures were readily visible including mitochondria, Golgi, endoplasmic reticulum and nuclear envelope membranes, as well as prominent chloroplast thylakoid membranes and individual lamella in grana stacks. This sample preparation protocol serves as a reliable starting point for routine plant volume electron microscopy.

In vivo transmission electron microscopy of the alternating structure of the protrusions between adjacent macrophage-like cells on micropatterns.

OBJECTIVES: We investigated the behavior of macrophages in the defined microtopography of materials. METHODS: Patterned cyclo-olefin polymer films were implanted into the femurs of seven-week-old rats. After 1 and 4 weeks, the rats were fixed with glutaraldehyde and OsO4, and their bones were observed with transmission electron microscopy (TEM). RESULTS: TEM and segmentation revealed an alternating structure in which multiple protrusions of adjacent macrophage-like cells overlapped. They were approximately 2 µm long and almost uniform in width, and were induced by the limited topography. CONCLUSION: New structures appeared between the macrophage-like cells as a result of microtopography.

Effect of Various Lasers With or Without Systemp.desensitizer on Dentine Tubules: An In Vitro Scanning Electron Microscopy Analysis.

Objective: The current study was carried out to evaluate the effects of laser and Systemp.desensitizer therapy. Further, scanning electron microscopy (SEM) was used to determine the effects of individual or combined desensitizers on human dentinal tubules. Background: The most common clinical condition that makes people uncomfortable is dentin hypersensitivity (DH). Both lasers and drugs that reduce sensitivity have been used to treat DH. Materials and methods: A total of 100 dentinal samples were taken from newly extracted third molars (affected) and divided into 10 groups (A to J), that is, control (A); Systemp.desensitizer (B); diode laser (980 nm) (C); Nd:YAG laser (D); Er:YAG laser (E); Er,Cr:YSGG laser (F); Systemp.desensitizer + diode laser (G); Systemp.desensitizer + Nd:YAG laser (H); Systemp.desensitizer + Er:YAG laser (I); and Systemp.desensitizer + Er,Cr:YSGG laser (J). SEM was used to evaluate the dentinal specimens in each group (longitudinal and transverse portions), and then images of each sample were captured (20 images/sample). In addition, the number of open dentinal tubules was counted and then the occlusion depth in dentinal tubules was measured. Mann-Whitney and Kruskal-Wallis tests were employed to analyze the obtained data. Results: All treatment procedures and protocols were effective in blocking dentinal tubules (p < 0.05). Compared with the other groups, dentinal tubules in the laser and laser combination therapy groups were significantly obstructed (p < 0.05). Diode and Nd:YAG lasers with or without Systemp.desensitizer showed significantly more tubule occlusion and greater sealing depth than Er:YAG and Er,Cr:YSGG lasers with or without Systemp.desensitizer (p < 0.05). Conclusions: In summary, lasers alone or in combination can play a significant role in occluding the dentinal tubules. However, combining the diode or Nd:YAG laser with Systemp.desensitizers is a more effective treatment strategy and may have immediate and long-lasting effects.

Disinfection of 3D-printed surgical guides using virgin coconut oil (in vitro study).

BACKGROUND/OBJECTIVE: Disinfection of a 3D-printed surgical guide is of utmost importance as it comes into contact with hard and soft tissue during implant placement so it poses a potential risk of pathogenic transmission. Methods used for disinfection in the surgical field should be reliable, practical, and safe for the instruments and the patients. The objectives of this study were to compare the antimicrobial potential of 100% Virgin Coconut Oil, 2% Glutaraldehyde, and 70% Ethyl Alcohol used to decontaminate 3D-printed surgical guides. MATERIALS AND METHODS: Thirty identical surgical guides were printed and cut into two halves (N = 60). Both halves were then contaminated with a defined amount of human saliva samples (2 ml). The first half (n = 30) was sub-grouped into three study groups which were immersed in one of the three disinfectants for 20 min as follows; group VCO was immersed in 100% Virgin Coconut Oil, group GA was immersed in 2% Glutaraldehyde, and group EA was immersed in 70% Ethyl Alcohol. The second half (n* = 30) was sub-grouped into three control groups which were immersed in sterile distilled water as follows group VCO*, group GA*, and group EA*. The microbial count was expressed as colony-forming units per plate and the comparison of the antimicrobial potential of the three tested disinfectants between the three study and three control groups was done using the One-Way ANOVA test. RESULTS: The culture results of three study groups revealed no bacterial growth with the highest % of reduction in the mean microbial count of the oral microorganisms (about100%) and an uncountable bacterial growth was shown between the three control groups (more than 100 CFU/plate) representing the baseline of the oral microorganisms. Therefore; statistically significant differences were found between the three control and three study groups (P < .001). CONCLUSION: The antimicrobial potential of Virgin Coconut Oil was comparable and equivalent to Glutaraldehyde and Ethyl Alcohol with a significant inhibitory action against oral pathogens.