Effect of Biotitania and Titania Addition on Bioactivity and Antibacterial Properties of Calcium Silicate Cement

Introduction: Nanoparticles are gaining more interest in dentistry for their antimicrobial, physical as well as other properties. This study aimed to evaluate the effect of adding two types of nanoparticles (NPs) on calcium silicate hydraulic cement’s (CSHC) unique bioactivity and antibacterial properties. Methods and Materials: Biotitania/AgCl NPs were synthetized and characterized for its morphology, types of formed functional groups and crystalline AgCl using field emission scanning electron microscope (FE-SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), Fourier transformation infrared spectroscopy (FT-IR) and thermo-gravimetric analysis (TGA). The former NPs and commercial titania (TiO2) NPs were added (0.5, 1.5 and 3-weight %) to commercial CSHS powder. A total of 140 disk-shaped specimens (10 mm×1 mm) were prepared (seven material groups per each test in addition to the eighth cell control group) to evaluate cell viability and alkaline phosphatase activity (ALP) after 3 and 12 days, respectively. All were incubated with mesenchymal stem cells. Antibacterial efficacy against Streptococcus mutans (S. mutans) was evaluated through the bacterial growth curve slopes while being in direct contact with the tested material groups for 18 h. Results: Addition of all NPs percentages had no significant effect (P>0.05) on cell viability in comparison to positive control CSHC. Commercial TiO2 NPs (0.5 weight %) had statistically significant lower values (P≤0.05) for bacterial growth curve slope. However, addition of all NPs percentages had significantly improved (P≤0.05) the ALP activity of CSHC with the most prominent effect to 3-weight% biotitania/AgCl NPs. Conclusion: Based on this in vitro study, addition of biotitania/AgCl NPs up to 3-weight% significantly improved the bioactivity of CSHC without having a significant negative impact on its antibacterial efficacy. Interestingly, the addition of commercial TiO2 even in small amounts can significantly improve CSHC antibacterial efficacy

Extraction of cellulose from bagasse for the synthesis of Alginate:Cellulose porous beads

This study aimed to develop the production of porous cellulose beads from bagasse. Alkali extraction with 6% sodium hydroxide was identified as the optimal solvent for cellulose, based on the swelling ratio. This process resulted in viscose cellulose solution with improved characteristics, including a density of 1.099 g/ml, viscosity of 0.024 Pa·s, molecular weight of 171.668 g/mol, and a swelling ratio of 50.8%. The beads fabrication using the cellulose extract combined with alginate led to the formation of beads with a homogeneous and rough surface. Calcium carbonate (CaCO3) was utilized as a porogen and zinc acetate served as the crosslinking agent. The optimal composition of alginate to cellulose xanthate for bead formation, determined through evaluations of bead geometry, swelling power, and surface porosity using SEM-EDX, was found to be a 2:2 ratio

Coating of surfaces of composite materials with enzymatically formed biosilica

Die Bildung kieselsäurehaltiger Spicula in marinen Schwämmen ist nur möglich durch die enzymatische Aktivität des Silicatein- in Verbindung mit der stöchiometrischen Selbstassemblierung des Enzyms mit anderen Schwammproteinen. Die vorliegende Arbeit basiert auf einem biomimetischen Ansatz mit dem Ziel, unterschiedliche Oberflächen für biotechnologische und biomedizinische Anwendungen mit Biosilica und Biotitania zu beschichten und zu funktionalisieren. Für biotechnologische Anwendungen ist dabei das Drucken von Cystein-getaggtem Silicatein auf Gold-Oberflächen von Bedeutung, denn es ermöglichte die Bildung definierter Biotitania-Strukturen (Anatas), welche als Photokatalysator den Abbau eines organischen Farbstoffs bewirkten. Des Weiteren zeigte sich die bio-inspirierte Modifikation von Tyrosin-Resten an rekombinantem Silicatein-(via Tyrosinase) als vielversprechendes Werkzeug zur Beschleunigung der Selbstassemblierung des Enzyms zu mesoskaligen Filamenten. Durch eine solche Modifikation konnte Silicatein auch auf der Oberfläche von anorganischen Partikeln immobilisiert werden, welches die Assemblierung von anorganisch-organischen Verbundwerkstoffen in wäßriger Umgebung förderte. Die resultierenden supramolekularen Strukturen könnten dabei in bio-inspirierten und biotechnologischen Anwendungen genutzt werden. Weiterhin wurde in der vorliegenden Arbeit die Sekundärstruktur von rekombinantem Silicatein- (Monomer und Oligomer) durch Raman Spektroskopie analysiert, nachdem das Protein gemäß einer neu etablierten Methode rückgefaltet worden war. Diese Spektraldaten zeigten insbesondere Änderungen der Proteinkonformation durch Solubilisierung und Oligomerisierung des Enzyms. Außerdem wurden die osteoinduzierenden und osteogenen Eigenschaften unterschiedlicher organischer Polymere, die herkömmlich als Knochenersatzmaterial genutzt werden, durch Oberflächenmodifikation mit Silicatein/Biosilica verbessert: Die bei der Kultivierung knochenbildender Zellen auf derart oberflächenbehandelten Materialien beobachtete verstärkte Biomineralisierung, Aktivierung der Alkalischen Phosphatase, und Ausbildung eines typischen zellulären Phänotyps verdeutlichen das Potential von Silicatein/Biosilica für der Herstellung neuartiger Implantat- und Knochenersatzmaterialien.The siliceous spicules of marine sponges are generated due to a collaborative effort between the enzymatic activity of silicatein- and the stoichiometric self-assembly of silicatein- with other sponge proteins. This study is based on a biomimetic approach that aims to design a functional biosilica and biotitania coating on different surfaces for biotechnological and biomedical application. For biotechnological application, the immobilization and patterning of cysteine-tagged silicatein on gold surfaces has assisted the deposition of biotitania (anatase polymorph), acting as photocatalyst for the degradation of organic dye (methylene blue). Furthermore, the bioinspired modification of tyrosine residues on the recombinant silicatein- surface via tyrosinase has shown to be a promising tool to accelerate and enlarge the molecular self-assembly of silicatein into mesoscale filamentous structures. By using the same enzymatic treatment, silicatein can be immobilized on the surfaces of inorganic particles, promoting the assembly of inorganic-organic composites in an aqueous environment. Both supramolecular structures have a potential utility in the manufacturing of bioinspired devices for many biotechnological applications. Furthermore, in the present study, secondary structural analysis of recombinant silicatein- in its monomeric and oligomeric forms was accomplished by Raman spectroscopy after refolding of the protein, according to a newly established methodology. The spectral data revealed conformational changes upon solubilization and oligomerization of this enzyme. On the other hand, silicatein/biosilica-based approaches are presented that have improved the osteoinductive and osteogenic properties of different organic biocompatible polymers, which are conventionally used as bone substitutes and for bone regeneration. By investigating the effect of functionalization of surfaces via biosilica on osteoblast-like cells, increased biomineralization, upregulation of alkaline phosphatase as an early osteogenic marker, and formation of an osteoblastic phenotype were confirmed. Therefore, the surface-modification of biomaterials with biosilica has resulted in various composite materials with new property combinations, greatly enhanced performance, and applicability as implants/bone substitutes

Selective deposition of CaCO3 on chemical gradient surface generated by plasma polymerization and its effect on cell adhesion

Calcic bioceramics have been widely used as substitutes or filling materials in bone grafts. Among them, CaCO3 is also favored due to its good biocompatibility and biodegradability. Herein, combined with chondroitin sulfate, CaCO3 can be selectively deposited on a chemical gradient surface generated by plasma polymerization. The chemical gradient in amino groups resulted in a gradient in deposited calcites number. The cell adhesion and spreading of SaoS-2 cells increased across the gradient surface with the increase of calcites number. These findings provide a controllable way to generate gradient CaCO3 coatings on scaffolds and/or implants used for bone regeneration.Xujie Liua, Tarek A. Elkhooly, Ranran Zhang, Qingling Feng, Akash Bachhuka, Krasimir Vasilev, Qiang Cai, Shengli M

Combating Bacterial Biofilm Formation in Urinary Catheter by Green Silver Nanoparticle

Urinary catheters are commonly associated with urinary tract infections. This study aims to inhibit bacterial colonisation and biofilm of urinary tract catheters. Silicon catheter pieces were varnished with green silver nanoparticles (AgNPs) using Pistacia lentiscus mastic to prevent bacterial colonisation. Pomegranate rind extract was used to synthesize AgNPs. AgNPs were characterized by UV-Vis spectroscopy, X-ray crystallography, and transmission electron microscopy (TEM). Results obtained revealed that the size of most AgNPs ranged between 15–25 nm and they took crystallised metal and oxidised forms. The amounts of released silver ions from 1 cm pieces of catheters coated with AgNPs were estimated for five days and ranged between 10.82 and 4.8 µg. AgNPs coated catheters significantly inhibited the colonisation of catheters by antibiotic-resistant clinical Gram-positive (Staphylococcus epidermidis and Staphylococcus aureus) and Gram-negative (Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Pseudomonas aeruginosa) bacteria. AgNPs-varnish was more active against Gram-negative bacteria than Gram-positive bacteria. The significant inhibitory effect of coated catheters lasted for 72 h for both Gram-positive and Gram-negative bacteria. Varnishing catheters with AgNPs may help to prevent bacterial colonisation and infections

Myelin oligodendrocyte glycoprotein antibody-associated optic neuritis and myelitis in COVID-19: a case report and a review of the literature.

BACKGROUND: Our case explored the spectrum of autoimmune and infectious neurological complications of Coronavirus Disease 2019. In addition, we also reviewed and discussed clinical features, neuroimaging, CSF findings, and outcomes in patients with COVID-19-associated Myelin Oligodendrocyte Glycoprotein Antibody Disorder (MOGAD) CNS inflammatory disorder. CASE PRESENTATION: Here we presented a case of post-Coronavirus Disease 2019 infection Myelin Oligodendrocyte Glycoprotein Antibody Disorder in a 41-year-old male who presented with gait instability, urinary retention, and confusion. Workup done in hospital showed transverse myelitis in cervical spine region and left optic neuritis. Laboratory findings showed Myelin Oligodendrocyte Glycoprotein-IgG antibodies were positive in serum (1:100), suggestive of post-COVID Myelin Oligodendrocyte Glycoprotein Antibody Disorder. CONCLUSION: To our knowledge, this is the first comprehensive case report and the literature review that includes the clinical features, neuroimaging, CSF findings, and outcomes in COVID-19-associated Myelin Oligodendrocyte Glycoprotein Antibody Disorder

CNS and PNS manifestation in immune checkpoint inhibitors: A systematic review.

INTRODUCTION: Immunomodulatory therapies, including the use of immune checkpoint inhibitors (ICIs), have made a profound impact on treatment of advanced cancers in recent decades. Neurologic immune-related adverse events (irAEs) related to use of these agents are rare but potentially fatal sequelae. This systematic reviewed aimed to describe onset, clinical features, treatment, and outcome of neurological irAEs following ICI usage. METHODS: A systematic literature search was conducted to identify all case reports (n = 168) and case series (n = 29) describing neurological irAEs (n = 255 patients). Patient demographics, clinical features, and clinical courses were extracted and used to assess statistical relationships between reported variables. RESULTS: Of reports describing neurological irAEs related to ICI use, the majority of cases were in men (66%) and patients above the age of fifty (85%). Disorders of the peripheral nervous system (PNS, 83%) were more common than central nervous system involvement. Neuromuscular disorders were the most common type of neurological irAE (e.g. myasthenia gravis, 36%), followed by peripheral neuropathies (16%), followed by all CNS disorders combined (15%). Most cases presented within the first 5 doses of ICI treatment. Most patients improved clinically, but 24% of cases were fatal. Mortality was highest in patients with neuromuscular irAEs, such as myasthenia gravis and myositis. CONCLUSION: This systematic literature review describes the largest collection of neurological irAEs to date including both CNS and PNS manifestations of ICIs. The information described herein can be used to better inform monitoring and treatment of patients undergoing treatment with ICIs

COVID-19 Vaccination and Neurological Manifestations: A Review of Case Reports and Case Series.

BACKGROUND: With 10 vaccines approved by the WHO and nearly 48% of people fully vaccinated worldwide, we have observed several individual case studies of neurological manifestations post-COVID-19 vaccination. Through this systematic review, we aim to discern these CNS and PNS manifestations following the COVID-19 vaccine to help produce methods to mitigate them. METHODS: We conducted a thorough literature search of Google Scholar and PubMed from 1 December 2020 until 10 October 2021 and included all the case studies of COVID-19 vaccine-associated neurological side effects. The literature search and data analysis were performed by two independent reviewers according to prespecified inclusion and exclusion criteria using PRISMA. RESULTS: The most common CNS manifestation was CVST (14.47%), found in females (64%) younger than 50 years (71%) after the first AstraZeneca dose (93%). Others included CNS demyelinating disorders (TM, ADEM, MS, NMOSD) (9.30%), encephalopathy/encephalitis (3.10%), and others (4.13%). The most common PNS manifestation was GBS (14.67%) found in males (71%) older than 50 years (79%), followed by Bell\u27s palsy (5.24%) and others (2.10%). Most occurred with the AstraZeneca (28.55%), Pfizer-BioNTech (9.18%), and Moderna (8.16%) vaccines. Nine (64%) out of the 14 patients with CVST died. However, most cases overall (42 out of 51) were non-fatal (82%). CONCLUSION: Several CNS and PNS adverse events have occurred post-COVID-19 vaccination, including CVST, GBS, and TM. High vigilance with early identification and treatment leads to better outcomes. Further studies with non-vaccinated controls might help in understanding the pathophysiologic mechanisms of these neurological manifestations following COVID-19 vaccination