Silane Modulation of Protein Conformation and Self-Assembly

This research focused on development of nanoparticle- based therapeutics against amyloid fibrils. Amyloid fibrils are associated with various diseases such as Parkinson’s, Huntington’s, mad cow disease, Alzheimer’s, and cataracts. Amyloid fibrils develop when proteins change their shape from a native form to a pathogenic “misfolded” form. The misfolded proteins have the ability to recruit more native proteins into the pathogenic forms, which self-assemble into amyloid fibrils that are hallmarks of the various protein-misfolding diseases listed above. Amyloid fibrils are highly resistant to degradation, which may contribute to the symptoms of amyloid diseases. Synthetic drugs, natural compounds, and antibodies are widely explored for potential to stop pathogenic protein assembly or to promote fibril degradation and clearance, but to date have had little success in relieving symptoms in clinical trials. In this research, I have synthesized fluorine-containing silica nanoparticles (NPs), and tested their fibril-inhibiting activity against amyloid fibrils formed by a non-pathogenic protein, β-lactoglobulin (BLG). These fluoro-silica NPs prevented BLG amyloid formation, whereas non-fluorinated nanoparticle analogs did not inhibit fibrillation under the same reaction conditions. The fluoro-silica NPs interacted with the BLG protein in a manner that prevented the protein from adopting a form that could self-assemble into fibrils. Additional applications of the NPs were explored as small-molecule drug-delivery systems; such that multiple functionalities could be introduced into a single nano- therapeutic

Silane Modulation of Protein Conformation and Self-Assembly

This research focused on development of nanoparticle- based therapeutics against amyloid fibrils. Amyloid fibrils are associated with various diseases such as Parkinson’s, Huntington’s, mad cow disease, Alzheimer’s, and cataracts. Amyloid fibrils develop when proteins change their shape from a native form to a pathogenic “misfolded” form. The misfolded proteins have the ability to recruit more native proteins into the pathogenic forms, which self-assemble into amyloid fibrils that are hallmarks of the various protein-misfolding diseases listed above. Amyloid fibrils are highly resistant to degradation, which may contribute to the symptoms of amyloid diseases. Synthetic drugs, natural compounds, and antibodies are widely explored for potential to stop pathogenic protein assembly or to promote fibril degradation and clearance, but to date have had little success in relieving symptoms in clinical trials. In this research, I have synthesized fluorine-containing silica nanoparticles (NPs), and tested their fibril-inhibiting activity against amyloid fibrils formed by a non-pathogenic protein, β-lactoglobulin (BLG). These fluoro-silica NPs prevented BLG amyloid formation, whereas non-fluorinated nanoparticle analogs did not inhibit fibrillation under the same reaction conditions. The fluoro-silica NPs interacted with the BLG protein in a manner that prevented the protein from adopting a form that could self-assemble into fibrils. Additional applications of the NPs were explored as small-molecule drug-delivery systems; such that multiple functionalities could be introduced into a single nano- therapeutic

Monitoring Silane Sol-Gel Kinetics with In-Situ Optical Turbidity Scanning and Dynamic Light Scattering

Organosilanes (e.g., R’-SiOR3) provide hydrophobic functionality in thin-film coatings, porous gels, and particles. Compared with tetraalkoxysilanes (SiOR4), organosilanes exhibit distinct reaction kinetics and assembly mechanisms arising from steric and electronic properties of the R’ group on the silicon atom. Here, the hydrolysis and condensation pathways of n-propyltrimethoxy silane (nPM) and a tri-fluorinated analog of nPM, 3,3,3-trifluoropropyl trimethoxy silane (3F), were investigated under aqueous conditions at pH 1.7, 2.0, 3.0, and 4.0. Prior to hydrolysis, 3F and nPM are insoluble in water and form a lens at the bottom (3F) or top (nPM) of the solutions. This phase separation was employed to follow reaction kinetics using a Turbiscan instrument to monitor hydrolysis through solubilization of the neat silane lens while simultaneously tracking condensation-induced turbidity throughout the bulk solution. Dynamic light scattering confirmed the silane condensation and particle aggregation processes reported by the turbidity scanning. Employing macroscopic phase separation of the starting reactants from the solvent further allows for control over the reaction kinetics, as the interfacial area can be readily controlled by reaction vessel geometry, namely by controlling the surface area to volume. In-situ turbidity scanning and dynamic light scattering revealed distinct reaction kinetics for nPM and 3F, attributable to the electron withdrawing and donating nature of the fluoro- and organo-side chains of 3F and nPM, respectively

Ambiguity tolerance and confusion avoidance in the intent to purchase farmed fish

Aquaculture products are presently becoming a crucial part of consumers’ diets. However, asymmetric information regarding farmed fish exposes consumers to ambiguity and often makes them confused. Therefore, this study aims to ascertain the levels of ambiguity tolerance (AT) and confusion avoidance (CA) related to farmed fish and to test if consumers’ AT and CA influence their purchase intent (PI) of such fish. The impact of demographics on consumers’ CA and AT is also explored. The data were obtained through a survey conducted on a randomly selected sample of 1053 households who either purchase and have purchased fish. The collected data were analyzed employing explorative factor analysis, structural equation modeling, and a simple regression model. The study demonstrates that AT had a positive and significant impact on the PI of farmed fish, and also reduced CA. However, the current high level of CA does not influence the PI of farmed fish

Fish wastewater treatment with "PACP" filter and reuse of the treated water

Powdered activated carbon pellet (PACP) filter was found very effective for the removal of chemical oxygen demand (COD) and nutrient from the fish wastewater. It was found in the study that fish waste water generated from rearing tilapia fish in a glass aquarium for 48 hours had high organic and nutrient content. This high organic and nutrient containing wastewater while passed through the 30 cm PACP filter could remove 90% COD, 93% phosphate and 85% ammonia nitrogen after 10 L of fish wastewater loading. The optimum flow rate for the PACP filter was 100 ml/min. In a comparative study it was found that PACP filter had a better COD removal capacity compared to a same size granular activated carbon (GAC) filter. After 10 L loading of fish wastewater GAC filter showed only 50% removal where as it was 90% for PACP filter. PACP filter did not reach to the breakthrough level or exhausted after continuous loading of 35 L of fish wastewater. Filtered PACP filter wastewater was used for rearing tilapia fish and up to the fourth water changing with a 48 hour interval, the fish was in good condition and no death occurred. Key words:

Clarification of turbid lake water using novel coagulant from peat soil

Malaysian peat soil usually categorised as tropical peat soil was chemically modified to work as a coagulant. This coagulant was found very effective for the removal of turbidity from lake and river water in a laboratory scale study. It was found that turbidity could be as low as 5 FTU after treatment with peat coagulant. Besides turbidity there was a reduction of suspended solids and chemical oxygen demand (COD) observed in this study. pH plays an important role for the clarification using peat coagulant. It was found that at acidic pH peat coagulant showed a better clarification compared to basic pH. It was mainly due to the chemical characteristics of the peat coagulant itself. The mechanism for the coagulation was suggested as charge adsorption neutralisation process. The effectiveness of peat coagulant was also compared with the commercial coagulant such as alum. Study revealed that the result obtained for different water quality parameters using alum as a coagulant was comparable with that of peat coagulant

Agro-Morphological, Physico-Chemical and Molecular Characterization of Rice Germplasm with Similar Names of Bangladesh

AbstractThirty-one duplicate and similar named rice germplasms of Bangladesh were studied to assess the genetic variation for the agro-morphological and physico-chemical traits and simple sequence repeat banding patterns during 2009–2012 at Bangladesh Rice Research Institute. The range of variations within the cultivar groups showed higher degree. The principal component analysis showed that the first five components with vector values > 1 contributed 82.90% of the total variations. The cluster analysis grouped the genotypes into four clusters, where no duplicate germplasm was found. The highest number (11) of genotypes was constellated in cluster I and the lowest (3) in cluster II. The intra- and inter-cluster distances were the maximum in cluster I (0.93) and between clusters I and IV (24.61), respectively, and the minimum in cluster IV (0.62) and between clusters I and III (5.07), respectively. The cluster mean revealed that the crosses between the genotypes of cluster I with those of clusters II and IV would exhibit high heterosis for maximum good characters. A total of 350 alleles varied from 3 (RM277) to 14 (RM21) with an average of 7.8 per locus were detected at 45 microsatellite loci across the 31 rice accessions. The gene diversity ranged from 0.48 to 0.90 with an average of 0.77, and the polymorphism information content values from 0.44 (RM133) to 0.89 (RM206) with an average of 0.74. RM206, RM21, RM55, RM258 and RM433 were considered as the best markers on the basis of their higher polymorphism information content values. The dendrogram from unweighted pair-group method with arithmetic average clustering also classified the genotypes into four groups, where group IV comprised of 20 genotypes and group III of one genotype, but no duplicate was found. Finally, similar and duplicate named rice germplasms need to be conserved in gene bank as are distinct from each other

Microwave Assisted Sol-Gel Synthesis of Silica-Spider Silk Composites

This study introduces a simple and environmentally friendly method to synthesize silica-protein nanocomposite materials using microwave energy to solubilize hydrophobic protein in an aqueous solution of pre-hydrolyzed organo- or fluoro-silane. Sol-gel functionality can be enhanced through biomacromolecule incorporation to tune mechanical properties, surface energy, and biocompatibility. Here, synthetic spider silk protein and organo- and fluoro-silane precursors were dissolved and mixed in weakly acidic aqueous solution using microwave technology. Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) images revealed the formation of spherical nanoparticles with sizes ranging from 100 to 500 nm depending, in part, on silane fluoro- or organo-side chain chemistry. The silane-protein interaction in the nanocomposite was assessed through infrared spectroscopy. Deconvoluted ATR-FTIR (Attenuated total reflectance Fourier-transform infrared spectroscopy) spectra revealed silane chemistry-specific conformational changes in the protein-silane nanocomposites. Relative to microwave-solubilized spider silk protein, the β structure content increased by 14% in the spider silk-organo-silica nanocomposites, but decreased by a net 20% in the spider silk-fluoro-silica nanocomposites. Methods of tuning the secondary structures, and in particular β-sheets that are the cross-linking moieties in spider silks and other self-assembling fibrillar proteins, may provide a unique means to promote protein interactions, favor subsequent epitaxial growth process, and enhance the properties of the protein-silane nanocomposites

Stealth cranioplasty in symptomatic adult chiari 1 malformations: Experience at Bangabandhu Sheikh Mujib Medical University

Background: The surgical management of symptomatic adult Chiari malformation type 1 (CM1) with or without syringomyelia (SM) continues to be a dilemma considering the outcomes. Objectives: The study aimed to compare the clinical outcomes between stealth cranioplasty (SC) and one of the most commonly practiced standard procedures, posterior fossa decompression with duraplasty (PFDD). Clinical outcomes between SC and another procedure posterior fossa decompression (PFD) were also compared. Methods: This comparative cross-sectional study was carried out on 37 males and 16 females symptomatic adult CM1 patients, ranging from 18 to 47 years of age from June 2019 to May 2021. Clinical outcomes were assessed, compared, and analyzed in terms of changes in clinical symptoms and signs, chicago chiari outcome scale (CCOS) score, and occurrence of complications.  Results: Of the 53 patients, 23, 19 and 11 underwent SC, PFDD, and PFD, respectively. There were no significant post-operative changes in symptoms and signs among groups except changes in limb weakness between SC and PFDD (P=0.004). Considering average CCOS score, SC performed better only than PFDD (P=0.003), while category-wise SC was better than both PFDD (P=0.004) and PFD (P=0.010). Considering complications, the PFDD group had a significantly higher rate of complications than the SC group (P=0.001), while there was no significant difference in the rate of complications between the PFD and SC groups. Conclusion: SC was found to have better clinical outcomes than the PFDD and PFD groups as a technique. Bangabandhu Sheikh Mujib Medical University Journal 2023;16(1): 08-1