Feasibility analysis of novel Maglev EDM by comparing with conventional micro EDM.

EDM is the most popular unconventional machining process. The present technology of EDM consists of a pulsed or capacitive type power supply in which the pulsed type power supply is more popular and effective. The following essential component of an EDM is its servo mechanism, which controls the gap between the electrodes and maintains the gap voltage. A low machining speed, complex power supply, and servo mechanism increase the cost of machining and the maintenance cost of an EDM machine. To resolve the above issues from the EDM, a novel servo mechanism has been developed, which is simple in design and low in cost and has the capacity to use direct current as a power source. The current work elaborates a brief description of the novel servo mechanism and its feasibility analysis. Pure DC power is employed with the conjunction of Maglev lucidity to refine the shortcomings of conventional micro EDM. The novel technology addresses the prime concerns of conventional micro EDMs and deficiencies such as the delayed response of mechanical actuators and a servo mechanism. The novel technology uses the logical arrangement of permanent magnets and electromagnets to address inadequacies such as short circuiting and arcing. The work outlook is to establish the viability of the novel Maglev EDM by a comparison with a similar range of parameters. The results on the novel technology showed an improved material removal rate (MRR), which was in the range of 76.6 µgm/min, whereas the specific energy and surface roughness were 33.4 Joule/microgram and 4.3 µm, respectively, while machining commercially pure titanium.

Potential liquid crystal-based biosensor depending on the interaction between liquid crystals and proteins.

Liquid crystal biosensors serve an essential role to detect biomolecules and chemical events as an effective, simple and early detection tool. The detection of Human serum albumin protein by a room temperature liquid crystal 4́-pentyl-4-biphenylcarbonitrile has been investigated using multiple techniques such as Polarizing optical microscope, Raman spectroscopy and molecular docking. The dynamics of director transfigurations of the liquid crystal molecule in the presence of protein through interactions are reported in the study. The change in the alignment of liquid crystal molecules during the nematic phase is observed under a polarizing optical microscope. The interactions through which the liquid crystal molecules bind with protein is depicted from the docking analysis. The residues in the active sites confirm their presence from docking studies. The spectral behaviour has been investigated by temperature-dependent Raman spectroscopy. The findings from Raman spectra for the interaction between these compounds correlates with the residues confirmed from molecular docking analysis.

Probiotic Effects of Lactobacillus paracasei 28.4 to Inhibit Streptococcus mutans in a Gellan-Based Formulation.

Streptococcus mutans is considered to be a major bacterium involved in dental caries, and the control of virulence mechanisms is fundamental to prevent disease. Probiotics present a promising preventive method; however, the use of probiotics requires its incorporation into delivery materials to facilitate oral colonization. Thus, we performed a comprehensive study examining preventive effects of Lactobacillus paracasei 28.4-enriched gellan hydrogel materials to inhibit S. mutans in planktonic and biofilm states, addressing its influence in the production of extracellular polysaccharides (EPS) and altered gene expression of several cariogenic virulence factors. L. paracasei 28.4, a strain isolated from the oral cavity of a caries-free individual, was incorporated in three gellan hydrogels (0.5%, 0.75%, and 1% w/v). The pretreatment with probiotic-gellan formulations provided a release of L. paracasei cells over 24 h that was sufficient to inhibit the planktonic growth of S. mutans, independent of the gellan concentrations and pH variations. This pretreatment also had inhibitory activity against S. mutans biofilms, exhibiting a reduction of 0.57 to 1.54 log10 in CFU/mL (p < 0.0001) and a decrease of 68.8 to 71.3% in total biomass (p < 0.0001) compared with the control group. These inhibitory effects were associated with the decreased production of EPS by 80% (p < 0.0001) and the downregulation of luxS, brpA, gbpB, and gtfB genes. The gellan formulation containing L. paracasei 28.4 exhibited probiotic effects for preventing S. mutans growth, biofilm formation, and production of cariogenic factors to suggest possible use in tooth decay prevention.

ß-Lactamase triggered visual detection of bacteria using cephalosporin functionalized biomaterials.

We report the conjugation of a chromogenic cephalosporin ß-lactamase (ßL) substrate to polymers and integration into biomaterials for facile, visual ßL detection. Identification of these bacterial enzymes, which are a leading cause of antibiotic resistance, is critical in the treatment of infectious diseases. The ßL substrate polymer conjugate undergoes a clear to deep yellow color change upon incubation with common pathogenic Gram-positive and Gram-negative bacteria species. We have demonstrated the feasibility of formulating hydrogels with the ßL substrate covalently tethered to a poly(ethylene glycol) (PEG) polymer matrix, exhibiting a visible color change in the presence of ßLs. This approach has the potential to be used in diagnostic biomaterials for point-of-care detection of ßL-producing bacteria, helping combat the spread of drug resistant microbes.

Inducing mesenchymal stem cell attachment on non-cell adhesive hydrogels through click chemistry.

We introduce an innovative approach to adhere mesenchymal stem cells (MSCs) to a hydrogel scaffold by nucleating adhesion through strain-promoted click chemistry. This method yields a significant increase in cell viability compared to non-functionalized and RGD peptide functionalized hydrogels, providing a promising alternative to traditional biomaterials cell attachment approaches.

Development of Probiotic Formulations for Oral Candidiasis Prevention: Gellan Gum as a Carrier To Deliver Lactobacillus paracasei 28.4.

Probiotics might provide an alternative approach for the control of oral candidiasis. However, studies on the antifungal activity of probiotics in the oral cavity are based on the consumption of yogurt or other dietary products, and it is necessary to use appropriate biomaterials and specific strains to obtain probiotic formulations targeted for local oral administration. In this study, we impregnated gellan gum, a natural biopolymer used as a food additive, with a probiotic and investigated its antifungal activity against Candida albicansLactobacillus paracasei 28.4, a strain recently isolated from the oral cavity of a caries-free individual, was incorporated in several concentrations of gellan gum (0.6% to 1% [wt/vol]). All tested concentrations could incorporate L. paracasei cells while maintaining bacterial viability. Probiotic-gellan gum formulations were stable for 7 days when stored at room temperature or 4°C. Long-term storage of bacterium-impregnated gellan gum was achieved when L. paracasei 28.4 was lyophilized. The probiotic-gellan gum formulations provided a release of L. paracasei cells over 24 h that was sufficient to inhibit the growth of C. albicans, with effects dependent on the cell concentrations incorporated into gellan gum. The probiotic-gellan gum formulations also had inhibitory activity against Candida sp. biofilms by reducing the number of Candida sp. cells (P < 0.0001), decreasing the total biomass (P = 0.0003), and impairing hyphae formation (P = 0.0002), compared to the control group which received no treatment. Interestingly, a probiotic formulation of 1% (wt/vol) gellan gum provided an oral colonization of L. paracasei in mice with approximately 6 log CFU/ml after 10 days. This formulation inhibited C. albicans growth (P < 0.0001), prevented the development of candidiasis lesions (P = 0.0013), and suppressed inflammation (P = 0.0006) compared to the mice not treated in the microscopic analysis of the tongue dorsum. These results indicate that gellan gum is a promising biomaterial and can be used as a carrier system to promote oral colonization for probiotics that prevent oral candidiasis.

Auranofin Releasing Antibacterial and Antibiofilm Polyurethane Intravascular Catheter Coatings.

Intravascular catheter related bloodstream infections (CRBSIs) are a leading cause of hospital-acquired infections worldwide, resulting not only in the burden of cost and morbidity for patients but also in the over-consumption of medical resources for hospitals and health care organizations. In this study, a novel auranofin releasing antibacterial and antibiofilm polyurethane (PU) catheter coating was developed and investigated for future use in preventing CRBSIs. Auranofin is an antirheumatic drug with recently identified antimicrobial properties. The drug carrier, PU, acts as a barrier surrounding the antibacterial agent, auranofin, to extend the drug release profile and improve its long-term antibacterial and antibiofilm efficacy and potentially the length of catheter implantation within a patient. The PU+auranofin coatings developed here were found to be highly stretchable (exhibiting ~500% percent elongation), which is important for the compliance of the material on a flexible catheter. PU+auranofin coated catheters were able to inhibit the growth of methicillin-resistant Staphylococcus aureus (MRSA) for 8 to 26 days depending on the specific drug concentration utilized during the dip coating process. The PU+auranofin coated catheters were also able to completely inhibit MRSA biofilm formation in vitro, an effect that was not observed with auranofin or PU alone. Lastly, these coatings were found to be hemocompatible with human erythrocytes and maintain liver cell viability.

Tunable antibiotic delivery from gellan hydrogels.

Hydrogels are used extensively in wound management. Many wounds are highly susceptible to infection and hydrogels can provide localized antibacterial delivery to treat and prevent this infection. There are several key considerations in designing antibacterial hydrogels for wound therapy, including preserving activity of encapsulated antibacterial agents, controlling drug release timescales and concentrations, and having the ability to conform to various wound configurations. In this work, we have used gellan, a U.S. Food and Drug Administration approved food additive, to develop antibiotic loaded hydrogels focusing on these criteria. These hydrogels were formed to exhibit a range of mechanical properties, which were investigated using oscillatory rheology. We denoted hydrogels formed using 1% w/v gellan and 1 mM CaCl2"ointment" hydrogels and those formed using 4% w/v gellan and 7 mM CaCl2"sheet" hydrogels. Vancomycin, a broad-spectrum antibiotic against Gram-positive bacteria, was encapsulated in these hydrogels both directly and/or in graphitized carbon black nanoparticles (CNPs). We found that vancomycin released from both sheet and ointment hydrogels at therapeutically effective concentrations over 9 days with CNPs and 6 days without CNPs. Applying the Ritger-Peppas and Peppas-Sahlin semi-empirical drug release models to sheet hydrogels, we determined that Fickian diffusion dominates release while case II relaxation also has a small contribution. The sheet hydrogels exhibited a larger overall release of the drug (83.6 ± 1.6% compared to 67.0 ± 2.6% for ointments), which was attributed to the larger swelling resulting from osmotic pressure differences between the hydrogel formulations and the release buffer. We also suggest that final drug release amounts are influenced by intermolecular interactions between vancomycin and gellan, which were observed via quartz crystal microbalance with dissipation monitoring. Lastly, we examined the potential for future in vivo translation. We demonstrated in vitro growth inhibition of Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus in the presence of these hydrogels, demonstrating that vancomycin activity is preserved upon encapsulation. We also showed that these hydrogels are non-toxic to important wound healing cells including fibroblasts and mesenchymal stem cells.