A modified colorimetric method of gelatinolytic assay using bacterial collagenase type II as a model

Methodological assessment of the reduction of dissemination risk and quantification of debris dispersion during dissection with a surgical aspirator

Objective

We developed an actuator-driven pulsed water jet (ADPJ) device to achieve maximal lesion dissection with minimal risk of normal structural damage. Despite the unique dissection characteristics, there is a risk of dissemination of tissue dispersion; however, there is no established method to quantify the dispersion. Hence, this study aimed to assess the factors associated with dispersion and propose a simple experimental method using spectrophotometry to evaluate the degree of dispersion in a wet field.

Results

Methylene blue-stained brain phantom gelatin was immersed in a chamber with distilled water solution and dissected with an ADPJ. The dispersed gelatin solution was stirred and warmed to dissolve. The absorbance of the solution was measured spectrophotometrically. First, a reference standard curve was constructed to confirm the relationship between the absorbance and the amount of the dispersed gelatin. A clear proportional correlation was observed, which indicated that absorbance measurements can help evaluate the amount of dispersion. Using this method, we revealed that a high dissection force, insufficient suction, and inappropriate long distance between the nozzle tip and the target were associated with increased dispersion. This method might constitute a versatile and reliable approach to evaluate dispersion and aid in the development of surgical devices.

Detection of Collagen-IV Using Highly Reflective Metal Nanoparticles-Immobilized Photosensitive Optical Fiber-Based MZI Structure

In this work, a photosensitive (PS) optical fiber-based Mach-Zehnder interferometer (MZI) structure is developed to diagnose the presence of collagen-IV in human bodies. The MZI is fabricated by sequentially splicing the single mode-multimode-photosensitive-multimode-single mode (SMPMS) fiber segments. The sensing region in MZI structure is created by partially removing the cladding of photosensitive fiber by using 40% hydrofluoric (HF) acid and depositing the layers of highly reflective metal nanoparticles (NPs) over it. The used NPs are polyvinyl alcohol stabilized silver nanoparticles (PVA-AgNPs), gold nanoparticles (AuNPs), and zinc oxide nanoparticles (ZnO-NPs). The size of AuNPs, PVA-AgNPs, and ZnO-NPs are 10 ± 0.2 nm,  ∼  4 -5 nm, and < 50 nm, respectively. In order to avoid the interference of other biomolecules in the detection of collagen-IV, the sensing region is functionalized with a collagenase enzyme. The sensing ability of the probe is ascertained by sensing a wide concentration of collagen solution ranging from 0 ng/ml to [Formula: see text]/ml. It is observed that sensing performance of probe is much better on immobilizing it with PVA-AgNPs and ZnO-NPs.

Gene expression of microbial gelatinase activity for porcine gelatine identification

In order to invent a porcine gelatine detection device using microbial resources, bacterial enzymes with a preference towards porcine gelatine and their candidate genes were evaluated. Five (n = 5) bacterial strains isolated from hot spring water and wet clay, Malaysia were screened for their gelatinase activity. The gelatinase enzyme was extracted and purified using ammonium sulphate precipitation prior to performing gelatinase assay on porcine, bovine and fish gelatine medium substrates. The G2 strain or Enterobacter aerogenes (Strain EA1) was selected for whole genome sequenced after showing a consistent trend of preference towards porcine gelatine. The gelatinase candidate gene gelEA1_9 was cloned and expressed. Based on one-way analysis of variance (ANOVA) with POST-HOC Duncan test (α = 0.05), the final product of gelEA1_9 was identified as a novel gelatinase. This gelatinase presented no significant difference in activity towards porcine gelatine. Hence, the present study demonstrated an enzyme-substrate interaction for porcine gelatine identification.

Paraclostridium dentum, a novel species with pathogenic features isolated from human dental plaque sample

A strictly anaerobic bacterial strain designated as SKVG24 was isolated from subgingival dental plaque samples of patients suffering from periodontitis. Cells were stained Gram-positive, rod shaped with endospore. The strain showed negative reaction to catalase and oxidase enzymes, but positive for gelatinase activity. Optimal growth was observed at 37 °C temperature and 7.0 pH. The 16S rRNA gene sequence BLAST analysis assigned strain SKVG24 to the genus Paraclostridium as it displayed 99.93% identity with P. benzoelyticum JC272^T followed by P. bifermentans ATCC 638^T (99.79%). However, average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) of the whole genome sequence showed <97% and <70% identity, respectively, with type strains of all closely related species. The G + C content of the DNA was 28.7 mol%. Total lipids profile showed presence of glycolipids as major lipids. Pathogenic features like hemolysis, gelatin hydrolysis and production of volatile sulfur compounds exhibited by strain SKVG24^T were analogous to those observed in the established oral pathogenic strains. Further, whole genome sequence analysis confirmed the presence of genes encoding virulence factors and provided genomic insights on adaptation of the strain in oral environment. Based on the phenotypic and genetic differences with phylogenetic relatives, strain SKVG24^T is proposed to represent a new species of the genus Paraclostridium with potential pathogenic ability, for which the name Paraclostridium dentum sp. nov., is suggested. The proposed type strain is SKVG24^T (MTCC 12836^T; = JCM 32760^T).

Amplified QCM biosensor for type IV collagenase based on collagenase-cleavage of gold nanoparticles functionalized peptide

The present study develops a rapid, simple and efficient method for the determination of type IV collagenase by using a specific peptide-modified quartz crystal microbalance (QCM). A small peptide (P1), contains a specific sequence (Pro-Gly) and a terminal cysteine, was synthetized and immobilized to the surface of QCM electrode via the reaction between Au and thiol of the cysteine. The peptide bond between proline and glycine can be specific hydrolyzed cleavage by type IV collagenase, which enabled the modified electrode with a high selectivity toward type IV collagenase. The cleaving process caused a frequency change of QCM to give a signal related to the concentration of type IV collagenase. The morphologies of the modified electrodes were characterized by scanning electron microscope (SEM) and the specific hydrolyzed cleavage process was monitored by QCM. When P1 was modified with gold nanoparticles (P1-Au NPs), the signal could be amplified to further enhance the sensitivity of the designed sensor due to the high-mass of the modified Au NPs. Compared the direct unamplified assay, the values obtained for the limit of detection for type IV collagenase was 0.96 ng mL^-1, yielding about 6.5 times of magnitude improvement in sensitivity. This signal enhanced peptide based QCM biosensor for type IV collagenase also showed good selectivity and sensitivity in complex matrix.

Discovery of potent inhibitor for matrix metalloproteinase-9 by pharmacophore based modeling and dynamics simulation studies

Matrix metalloproteinase-9 (MMP-9) is an attractive target for anticancer therapy. In the present study ligand based pharmacophore modeling was performed to elucidate the structural elements for a diverse class of MMP-9 inhibitors. The pharmacophore model was validated through Güner-Henry (GH) scoring method. The final pharmacophore model consisted of three hydrogen bond acceptors (HBA), and two ring aromatic regions (RA). This model was utilized to screen the natural compound database to seek novel compounds as MMP-9 inhibitors. The identified hits were validated using molecular docking and molecular dynamics simulation studies. Finally, one compound named Hinokiflavone from Juniperus communis had high binding free energy of -26.54kJ/mol compared with the known inhibitors of MMP-9. Cytotoxicity for hinokiflavone was evaluated by MTT assay. Inhibition of MMP-9 in the presence of hinokiflavone was detected by gelatin zymography and gelatinolytic inhibition assay. Results revealed that the natural compounds derived based on the developed pharmacophore model would be useful for further design and development of MMP-9 inhibitors.