Antibacterial and anti-biofilm activities of antibiotic-free phosphatidylglycerol/docosahexaenoic acid lamellar and non-lamellar liquid crystalline nanoparticles.

Infectious diseases, particularly those associated with biofilms, are challenging to treat due to an increased tolerance to commonly used antibiotics. This underscores the urgent need for innovative antimicrobial strategies. Here, we present an alternative simple-by-design approach focusing on the development of biocompatible and antibiotic-free nanocarriers from docosahexaenoic acid (DHA) that has the potential to combat microbial infections and phosphatidylglycerol (DOPG), which is attractive for use as a biocompatible prominent amphiphilic component of Gram-positive bacterial cell membranes. We assessed the anti-bacterial and anti-biofilm activities of these nanoformulations (hexosomes and vesicles) against S. aureus and S. epidermidis, which are the most common causes of infections on catheters and medical devices by different methods (including resazurin assay, time-kill assay, and confocal laser scanning microscopy on an in vitro catheter biofilm model). In a DHA-concentration-dependent manner, these nano-self-assemblies demonstrated strong anti-bacterial and anti-biofilm activities, particularly against S. aureus. A five-fold reduction of the planktonic and a four-fold reduction of biofilm populations of S. aureus were observed after treatment with hexosomes. The nanoparticles had a bacteriostatic effect against S. epidermidis planktonic cells but no anti-biofilm activity was detected. We discuss the findings in terms of nanoparticle-bacterial cell interactions, plausible alterations in the phospholipid membrane composition, and potential penetration of DHA into these membranes, leading to changes in their structural and biophysical properties. The implications for the future development of biocompatible nanocarriers for the delivery of DHA alone or in combination with other anti-bacterial agents are discussed, as novel treatment strategies of Gram-positive infections, including biofilm-associated infections.

The Synergistic Effect of Polystyrene/Modified Boron Nitride Composites for Enhanced Mechanical, Thermal and Conductive Properties.

Thermal conductivity (TC) and thermal stability are the basic requirements and highly desirable properties in thermal management, heat storage and heat transfer applications. This work is regarding the fabrication of polystyrene/boron nitride composites and melt extruded to produce good thermal stability, increased thermal conductivity and enhanced mechanical properties. Our strategy is potentially applicable to produce thermally conductive composites of low cost over large scale. Boron nitride powder is bath sonicated in 10% NH3 solution to avoid its agglomeration and tendency toward entanglement in a polymer matrix. An approximately 67.43% increase in thermal conductivity and 69.37% increase in tensile strength as well as 56 multiple increases in thermal stability of the optimum samples were achieved. The developed polymeric composites are potentially applicable in the electronic industry, especially in electronic devices used for 5G, heat sink and several other aviation applications.

Impedance Spectroscopy Analysis of PbSe Nanostructures Deposited by Aerosol Assisted Chemical Vapor Deposition Approach.

This research endeavor aimed to synthesize the lead (II) diphenyldiselenophosphinate complex and its use to obtain lead selenide nanostructured depositions and further the impedance spectroscopic analysis of these obtained PbSe nanostructures, to determine their roles in the electronics industry. The aerosol-assisted chemical vapor deposition technique was used to provide lead selenide deposition by decomposition of the complex at different temperatures using the glass substrates. The obtained films were revealed to be a pure cubic phase PbSe, as confirmed by X-ray diffraction analysis. SEM and TEM micrographs demonstrated three-dimensionally grown interlocked or aggregated nanocubes of the obtained PbSe. Characteristic dielectric measurements and the impedance spectroscopy analysis at room temperature were executed to evaluate PbSe properties over the frequency range of 100 Hz-5 MHz. The dielectric constant and dielectric loss gave similar trends, along with altering frequency, which was well explained by the Koops theory and Maxwell-Wagner theory. The effective short-range translational carrier hopping gave rise to an overdue remarkable increase in ac conductivity (σac) on the frequency increase. Fitting of a complex impedance plot was carried out with an equivalent circuit model (Rg Cg) (Rgb Qgb Cgb), which proved that grains, as well as grain boundaries, are responsible for the relaxation processes. The asymmetric depressed semicircle with the center lower to the impedance real axis provided a clear explanation of non-Debye dielectric behavior.

An efficient approach for development and optimisation of curcumin-loaded solid lipid nanoparticles' patch for transdermal delivery.

This study aimed to develop and optimise a Curcumin-loaded SLNs (C-SLNs) patch through a new approach for transdermal delivery. C-SLNs were optimised through the response surface central composite design using the modified injection method. Optimised C-SLNs were loaded into a polyvinyl alcohol-based patch through the backing membrane method. Compatibility studies (FTIR, XRPD), in vitro release, ex vivo skin permeation, accelerated stability, and evaluation studies of the patch were also performed. Prepared C-SLNs exhibited average particle diameter of 170 ± 2 nm with an encapsulation efficiency of 90 ± 3.5% (w/w) while SEM illustrated spherical shape of particles. In vitro release data ensured a sustained release for up to 72 hours. The enhancement ratio of C-SLNs based patch with permeation enhancer (PE) was high up to 6.5 folds as compared to patch without PE. It is concluded that the modified injection method is simple, economical, and less time consuming for the development of C-SLNs patch for the transdermal route.

Cannabinoids and Terpenes as an Antibacterial and Antibiofouling Promotor for PES Water Filtration Membranes.

Plant phytochemicals have potential decontaminating properties, however, their role in the amelioration of hydrophobic water filtration membranes have not been elucidated yet. In this work, phytochemicals (i.e., cannabinoids (C) and terpenes (T) from C. sativa) were revealed for their antibacterial activity against different Gram-positive and Gram-negative bacteria. As such, a synergistic relationship was observed between the two against all strains. These phytochemicals individually and in combination were used to prepare polyethersulfone (PES) hybrid membranes. Membrane characterizations were carried out using scanning electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy. Moreover, contact angle, water retention, surface roughness, mechanical testing, and X-ray florescence analysis were also carried out. According to results, the CT-PES hybrid membrane exhibited the lowest contact angle (40°), the highest water retention (70%), and smallest average pore size (0.04 µm). The hybrid membrane also exhibited improved water flux with no surface leaching. Quantitative bacterial decline analysis of the CT-PES hybrid membranes confirmed an effective antibacterial performance against Gram-positive and Gram-negative bacteria. The results of this study established cannabinoids and terpenes as an inexpensive solution for PES membrane surface modification. These hybrid membranes can be easily deployed at an industrial scale for water filtration purposes.

Formulation and Evaluation of Novel Thiolated Intra Pocket Periodontal Composite Membrane of Doxycycline.

Localized intra-pocket, retentive, biodegradable, prolonged release thiolated membrane can provide an improved therapeutic efficacy of doxycycline at the site of action with evading off target side effects. To this end, thiolated chitosan-hyaluronic acid composite polymeric complex next-generation of the periodontal membrane was manufactured by solvent casting method. FTIR spectroscopic analysis displayed successful immobilization of thiol groups on the manufactured thiolated periodontal membrane. Moreover, XRD, DSC, AFM and TGA of the membrane confirmed the compatibility of ingredients and modifications in surface chemistry. The thiolated periodontal film was also investigated in terms of thickness, weight uniformity, water-uptake capacity, drug content, pH, entrapment efficiency, lysozymal degradation and release patterns. Also, mucoadhesion profile was explored on gingival mucosa. The immobilized thiol groups on thiolated chitosan and thiolated hyaluronate were found to be 168 ± 11 µM/g (mean ± SD, n = 3) and 189 ± 8 µM/g (mean ± SD, n = 3) respectively. Swelling capacity of the thiolated periodontal membrane was significantly ∼2-fold higher (p < 0.05) as compared to unmodified membrane. The obtained thiolated membrane depicted 3 -old higher mucoadhesive features as compared to the un-modified membrane. In vitro release kinetics indicated approximately more than 80% prolonged release within 7 days. Mechanical strength of the Thiolated bandage was also significantly ∼2-fold higher (p < 0.05) as compared to unmodified membrane. Ex-vivo retention study revealed enhanced retention of thiolated membrane as compared to unmodified membrane. In-vitro antimicrobial studies demonstrated that thiolated membrane could efficiently kill Porphyromonas gingivalis cells as compared to the native membrane. Moreover, ex-vivo biodegradation results indicated that 90% of the thiolated membrane was biodegradable in 28 days. Based on these findings, thiolated next-generation of the periodontal membrane seems to be promising for periodontitis therapy.