Asphaltene-derived nanocomposites for the removal of emerging pollutants and its antimicrobial effects: batch and continuous column studies

Emerging contaminants are diverse ecotoxic materials requiring unique treatment for removal. Asphaltenes are environmentally hazardous carbon-rich solid waste product of the petroleum industry. In the current work, asphaltene-derived activated carbon (AC) was loaded with silver (Ag/AC) and used to remove amoxicillin (AMX) and tetracycline (TC) from aqueous phase. The prepared Ag/AC was characterised using FESEM, FTIR, XRD and surface area analysis. The FESEM micrographs confirmed the spherical silver nanoparticle-laden porous AC, and the BET surface area was found to be 213 m2/g. Batch adsorption studies were performed, and the equilibrium data were fit into adsorption isotherm and kinetic models. The Ag/AC exhibited superior monolayer adsorption capacity of 1012 mg/g and 770 mg/g for AMX and TC, respectively. The continuous column studies were also performed to evaluate the breakthrough parameters. Furthermore, the antimicrobial activity of the adsorbent was evaluated using zone of inhibition studies. Ag/AC was found to have an 8-mm-diameter zone of microbial inhibition. The obtained results showed that Ag/AC was a promising material for the removal of antibiotics and inhibition of resistance-developed mutated microbes in effluent water.

Synthesis and antimicrobial studies of cadasides analogues via on-resin esterification

A series of cadasides analogues have been prepared via a combination of solid-phase peptide synthesis and solution-phase cyclization. Primary structure-activity relationship studies of cadasides have also been established and revealed the critical roles of unnatural amino acid residues, which will facilitate the further development of cadasides analogues with improved antimicrobial activities.

Synthesis, characterization, and biological properties of mono-, di- and poly-nuclear bismuth(III) halide complexes containing thiophene-2-carbaldehyde thiosemicarbazones

In order to investigate the coordination chemistry and pharmacological applications of bismuth compounds, a series of new bismuth(III) halide thiosemicarbazone complexes were synthesized. The reactions of thiophene-2-carbaldehyde-N-substituted thiosemicarbazones with bismuth(III) halides resulted in the formation of the {[[BiCl₂(η¹-S-Httsc)₄]⁺.Cl^-][BiCl₂(μ₂-Cl)(η¹-S-Httsc)₂]₂} (1), {[BiCl₃(η¹-S-Htmtsc)₃].CH₃OH} (2), {[BiCl₃(η¹-S-Htetsc)₃].CH₃OH} (3), {[BiBr₂(μ₂-Br)(η¹-S-Httsc)₂]₂.CH₃OH} (4), {[BiBr₂(μ₂-Br)(η¹-S-Htmtsc)₂]_n} (5), and {[BiI₂(μ₂-I)(η¹-S-Httsc)₂]₂} (6) complexes (Httsc: thiophene-2-carbaldehyde thiosemicarbazone, Htmtsc: thiophene-2-carbaldehyde-N-methyl thiosemicarbazone, Htetsc: thiophene-2-carbaldehyde-N-ethyl thiosemicarbazone). The complexes were characterized by a number of different spectroscopic techniques and the crystal structures of all bismuth(III) complexes (1-6) were determined by using single crystal X-ray diffraction study. In addition, the thermal stability of the complexes was compared using Thermogravimetric-differential thermal analysis. Crystal structures of the two free ligands, thiophene-2-carbaldehyde-N-methyl-thiosemicarbazone and thiophene-2-carbaldehyde-N-ethyl-thiosemicarbazone, were also determined by using single crystal X-ray diffraction analysis. The Hirshfeld surface of the bismuth(III) complexes and free ligands were additionally analyzed to verify the intermolecular interactions. Biological studies showed that all six bismuth(III) thiosemicarbazone complexes (1-6) exhibited biological activities against selected bacteria and the human breast adenocarcinoma (MCF-7) cell line.

Experimental Design Supported Liposomal Aztreonam Delivery: In Vitro Studies

Purpose: The present study focuses on a systemic approach to develop liposomal aztreonam as a promising dosage form for inhalation therapy in the treatment of pneumonia and explores the in-vitro antimicrobial and cell uptake efficacy. Methods: Liposomes were prepared by ethanol injection method using the lipids - soya phosphatidylcholine (SP) and cholesterol (CH). A central composite design (CCD) was employed to optimize the lipid composition to evaluate the effect on vesicle size, zeta potential and entrapment efficiency of the formulation. A numerical and graphical optimization was carried out to predict the optimized blend. The optimized formulation was characterized for vesicle size, surface charge, encapsulation, surface morphology, differential scanning calorimetry (DSC), powder X Ray Diffraction (PXRD), thermogravimetric analysis (TGA), in vitro diffusion, accelerated stability studies, antimicrobial studies on Pseudomonas aeruginosa NCIM 2200 and in vitro cell uptake studies. Results: The optimized formulation was found to have a particle size of 144 nm, a surface charge of -35 mV, with satisfactory drug entrapment. The surface morphology study proved the formation of nanosized vesicles. The drug release from liposomal matrix was biphasic in nature. The solid-state study revealed the reason for good encapsulation of drug. The moisture retention capacity was found to be minimum. The anti-microbial study revealed the potential antibacterial activity of the optimized formulation over the pure drug. The formulation was found to be safe on the epithelial cells and showed a marked increase in cellular uptake of aztreonam in a lipid carrier. Conclusion: It can be concluded that the optimized liposomal aztreonam could be considered as a promising approach for the delivery of aztreonam through inhalation.

Highly ordered functionalized mesoporous silicate nanoparticles reinforced poly (lactic acid) gatekeeper surface for infection treatment

The controlled release of a drug considers the key feature of the delivery carrier that enhances therapeutic efficacy. This study was aimed at design, synthesis of nano valve and capping systems onto caged functionalized mesoporous silica nanoparticles (SBA15) with nanoflowers polylactic acid (PLA-NF). Levofloxacin (LVX) as a specific model drug was encapsulated onto series; SBA15, SBA15@NH2, and SBA15@NH2/PLA. The examined nanocarriers released in a controlled fashion by external stimuli. The delivery vehicle based on PLA-NF coated SBA15@NH2, potent conjugated with LVX with experienced a high extent of trapping content with fast releasing by pH regulating mechanism. In vial LVX released profile and in vitro antifungal forceful of the selected microbes were detected. However, SBA15@NH2/PLA exhibited pore size, surface area and pore volume 5.4 nm, 163 and 0.011 respectively, but the significantly clear zone was obtained with Staphylococcus aureus ATCC 6538 (G+ve), Escherichia coli ATCC 25922 (G-ve), Candida albicans ATCC 10231 (yeast) and Aspergillus niger NRRL A-326 (fungus). Viability test avouch that rising functionality enhanced cytocompatibility and non-toxicity profile. Based on the aforementioned promising data, this type of nanocarriers offers when functionalized with targeting cells, the accessibility to deliver antibiotics onto nanosystem for increased potency against microbes and reduce side effects.

Niosomally encapsulated silver sulfadiazine gel for burn treatment

Silver sulfadiazine (SSD) is the antibacterial of choice for the treatment of burn. The current marketed formulation of SSD is 1% w/w water soluble cream, which requires frequent applications, which is very painful to patients. Niosomes were prepared by a thin film hydration method. The in vitro antimicrobial efficiency of niosomal SSD (18 ± 0.5 mm) was as good as that of marketed cream (17 ± 0.5 mm) against Staphylococcus aureus even when used in half the concentration (0.5%) of marketed cream (1%). Further SSD (0.5% w/w) niosomal gel was prepared using 1.6% carbopol 934. It was evident through in vitro permeation studies that SSD release was considerably retarded from both niosomes and niosomal gel in comparison with marketed cream thereby decreasing the dosing frequency. In-vivo study demonstrated that a niosomal gel containing 0.5% w/w SSD was more effective in burn wound healing compared to 1% w/w marketed cream even when applied once a day.