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There is still an urgent need to develop hydrogels with intelligent antibacterial ability to achieve on-demand treatment of infected wounds and accelerate wound healing by improving the regeneration microenvironment. We proposed a strategy of hydrogel wound dressing with bacteria-responsive self-activating antibacterial property and multiple nanozyme activities to remodel the regeneration microenvironment in order to significantly promote infected wound healing. Specifically, pH-responsive H2O2 self-supplying composite nanozyme (MSCO) and pH/enzyme-sensitive bacteria-responsive triblock micelles encapsulated with lactate oxidase (PPEL) were prepared and encapsulated in hydrogels composed of L-arginine-modified chitosan (CA) and phenylboronic acid-modified oxidized dextran (ODP) to form a cascade bacteria-responsive self-activating antibacterial composite hydrogel platform. The hydrogels respond to multifactorial changes of the bacterial metabolic microenvironment to achieve on-demand antibacterial and biofilm eradication through transformation of bacterial metabolites, and chemodynamic therapy enhanced by nanozyme activity in conjunction with self-driven nitric oxide (NO) release. The composite hydrogel showed 'self-diagnostic' treatment for changes in the wound microenvironment. Through self-activating antibacterial therapy in the infection stage to self-adaptive oxidative stress relief and angiogenesis in the post-infection stage, it promotes wound closure, accelerates wound collagen deposition and angiogenesis, and completely improves the microenvironment of infected wound regeneration, which provides a new method for the design of intelligent wound dressings. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the activity of Hydnophytum formicarum Jack (Ant Plant) tuber extract against Staphylococcus aureus and Escherichia coli and the mode of action of the extract on bacterial responses. The antibacterial activity was determined using agar well diffusion method. Resazurin-based 96-well microdilution method was used to determine the Minimal Inhibitory Concentrations (MIC) of the extract. Mode of action on bacterial death and response patterns to the extract were assessed by flow cytometry using membrane integrity and granularity profiles. The results, based on serial dilution and zones of inhibition against the bacteria, showed that 2,000 µg/well was potent against S. aureus (16.33±1.53 mm) and E. coli (14.33±0.58 mm). For S. aureus, the MIC concentration was 8,000 µg/mL, while 4,000 µg/mL concentration exhibited activity against E. coli. Flow cytometric profiles confirmed loss of intracellular components, followed by death, for both bacteria. Bacterial responses to the extract had consistent dose- and time-dependent behavior. This is the first mode of action study on bacterial responses to H. formicarum tuber extract. The results suggest that the extract of H. formicarum tuber could serve as a source of an initial active ingredient for developing effective medicines to battle infections caused by pathogens. [ABSTRACT FROM AUTHOR]

The present study investigated the variation in surface free energy, adhesion strength, and bacterial attachment during early colonization. Two different sizes of micro dimple textured surface MDS 400 and MDS 200 on Ti6Al4V were fabricated using mechanical micro-milling and studied with an un-textured surface. One polar (water) and dispersive liquid (diiodomethane) were used to study the work of adhesion and surface free energy of both surfaces. The Neumann method and Owen & Wendt approach were used to calculate the SFE. EDS analysis was carried out to check the surface composition. E. coli bacterial strain was used to study the early colonization responses using FESEM and optical microscope. Results indicate that the formed textures are uniform with good quality and as per the design of experiment. Area surface roughness values of the textured surface have been increased from UTS. Besides, no tool wear debris has been found on textured surfaces. SFE and adhesion strength of water and diiodomethane increase due to surface texturing and initial colonization of bacteria on textured surfaces is in the form of E. coli cellular chains has been observed. The current study offers insights into the surface free energy, adhesion strength of water and diiodomethane, and bacterial attachment during the early stage of colonization. [ABSTRACT FROM AUTHOR]

Problem Methods for monocyte purification are common but few work with umbilical cord monocytes that do not activate the cell for subsequent culture analysis. Methods of study The collection procedure avoids use of needles and procedures that variably activate blood clotting and uses a purification procedure that involves diluted Ficoll, autologous serum to remove platelets and 42% and 51% Percoll step gradients for the final purification. The resulting monocytes were stimulated with bacterial lipopolysaccharide and formalin-treated bacteria Escherichia coli and group B streptococci (GBS) to secrete TNF-α and IL-1β, measured by ELISA. Results The purification procedure results in non-active but stimulation-competent monocytes with high yields (2.3–9 × 107 cells) and purity (from 70% to 98%). Conclusion We describe a procedure that is easy, uses common reagents and provides a uniformly high yield and purity of non-activated fetal monocytes for studies of innate defense responses. [ABSTRACT FROM AUTHOR]

The UV dose-response behavior of laboratory cultures of waterborne bacteria were examined for UV doses ranging from ca. 0 -100 mW.s/cm2 using a collimated-beam reactor. Specific physiological responses measured in these tests included viability (abilityto reproduce) and respiration (oxygen uptake rate). The results of these exposures indicated that resistance to UV-imposed loss of viability in E. coli cultures can be partially attributed to agglomeration during the irradiation process. From these results, it is conjecturedthat a bacterial population may be comprised of two sub-populations:one with low resistance (discrete or paired cells) and a second withhigh resistance (bacterial aggregates). A small fraction of the high-resistance portion of the population appears to be essentially unaffected by UV irradiation, thereby causing a discontinuity in the measured dose-response behavior. Moreover, the dose-response behavior of the highly resistant fraction is variable and difficult to describe quantitatively. The basis of these statements and most information in the literature is microbial viability as quantified by the membrane filtration assay. In contrast to these findings, the results of analyses for bacterial activity (respiration) suggest that comparatively little change in the population can be found to result from UV irradiation. This suggests that UV radiation accomplishes inactivation of the bacteria, but does not 'kill' the bacterial cells per se, thereby highlighting the importance of considering bacterial repair processes inthe design of UV disinfection systems. [ABSTRACT FROM AUTHOR]