Elements Of X Ray Diffraction

https://www.massey.ac.nz/%7Eychisti/Lipases.pdf

Production, purification, characterization, and applications of lipases.

Use of silver and silver salts is as old as human civilization but the fabrication of silver nanoparticles (Ag NPs) has only recently been recognized. They have been specifically used in agriculture and medicine as antibacterial, antifungal and antioxidants. It has been demonstrated that Ag NPs arrest the growth and multiplication of many bacteria such as Bacillus cereus, Staphylococcus aureus, Citrobacter koseri, Salmonella typhii, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumonia, Vibrio parahaemolyticus and fungus Candida albicans by binding Ag/Ag+ with the biomolecules present in the microbial cells. It has been suggested that Ag NPs produce reactive oxygen species and free radicals which cause apoptosis leading to cell death preventing their replication. Since Ag NPs are smaller than the microorganisms, they diffuse into cell and rupture the cell wall which has been shown from SEM and TEM images of the suspension containing nanoparticles and pathogens. It has also been shown that smaller nanoparticles are more toxic than the bigger ones. Ag NPs are also used in packaging to prevent damage of food products by pathogens. The toxicity of Ag NPs is dependent on the size, concentration, pH of the medium and exposure time to pathogens.

/pdf/a-review-on-biosynthesis-of-silver-nanoparticles-and-their-ivx9t7t18x.pdf

A review on biosynthesis of silver nanoparticles and their biocidal properties.

The acronym ESKAPE includes six nosocomial pathogens that exhibit multidrug resistance and virulence: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. Persistent use of antibiotics has provoked the emergence of multidrug resistant (MDR) and extensively drug resistant (XDR) bacteria, which render even the most effective drugs ineffective. Extended spectrum β-lactamase (ESBL) and carbapenemase producing Gram negative bacteria have emerged as an important therapeutic challenge. Development of novel therapeutics to treat drug resistant infections, especially those caused by ESKAPE pathogens is the need of the hour. Alternative therapies such as use of antibiotics in combination or with adjuvants, bacteriophages, antimicrobial peptides, nanoparticles, and photodynamic light therapy are widely reported. Many reviews published till date describe these therapies with respect to the various agents used, their dosage details and mechanism of action against MDR pathogens but very few have focused specifically on ESKAPE. The objective of this review is to describe the alternative therapies reported to treat ESKAPE infections, their advantages and limitations, potential application in vivo, and status in clinical trials. The review further highlights the importance of a combinatorial approach, wherein two or more therapies are used in combination in order to overcome their individual limitations, additional studies on which are warranted, before translating them into clinical practice. These advances could possibly give an alternate solution or extend the lifetime of current antimicrobials.

/pdf/emerging-strategies-to-combat-eskape-pathogens-in-the-era-of-mchli3dllg.pdf

Emerging Strategies to Combat ESKAPE Pathogens in the Era of Antimicrobial Resistance: A Review.

Functional copolymers of N-isopropylacrylamide for bioengineering applications

Production of exogenous lipases by bacteria, fungi, and actinomycetes

The different analogues of ebselen—unsubstituted benzisoselenazol-3(2H)-one (2a) 2-pyridylbenzisoselenazol-3(2H)-ones (2b–h) and 7-azabenzisoselenazol-3(2H)-ones (3a–j) were designed as new selenium-containing antiviral and antimicrobial agents and synthesized. Some of them were found in the antiviral assay in vitro to be strong inhibitors of cythopatic activity of herpes simplex virus type 1—HSV-1 (compounds 2a,b,f,h, 3a–j) and encephalomyocarditis virus—EMCV (compounds 2a,h, 3a–f,k,l). The compounds 2a,h and 3a–e,j were found to have an appreciable activity against Gram-positive bacteria (Staphylococcus aureus and Bacillus) in vitro, some of them inhibited growth of pathogenic yeasts (Candida albicans) (3a,b) and filamentous fungi (3a–e,f).

Azaanalogues of ebselen as antimicrobial and antiviral agents: synthesis and properties.

A new method for green synthesis of silver nanoparticles using the cell-free filtrate of Penicillium nalgiovense AJ12 as reducing and protecting agent was described. The pathway is based on the reduction of Ag1+ by protein(s). Various techniques such as UV–Vis spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared and Zeta potential measurements were used to characterize the silver nanoparticle obtained. The results revealed synthesis of the spherical silver nanoparticles coated with protein(s). The average size of the particles obtained from TEM was 15.2 ± 2.6 nm. DLS measurements showed that the particle size was higher than that estimated from TEM measurements and was 25.2 ± 2.8 nm. Studies on the role of the cell-free filtrate proteins in the synthesis of silver nanoparticles indicated that the process is non-enzymatic but involves amino acids interactions with silver ions. It was found that the aqueous silver nanoparticles suspensions exhibited excellent stability over a wide range of ionic strength, pH and temperature.

Green Synthesis and Characterization of Silver Nanoparticles Using Ascomycota Fungi Penicillium nalgiovense AJ12

Production and some properties of lipase from penicillium citrinum

A surface modification of polyamide 6 (PA), polyethylene terephthalate (PET) and polypropylene (PP) textiles was performed using zinc oxide to obtain antibacterial layer. ZnO microrods were synthesized on ZnO nanoparticles (NPs) as a nucleus centers by chemical bath deposition (CBD) process. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) indicated that wurzite ZnO microrods were obtained on every sample. Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM) and Liquid Absorption Capacity (LAC) analysis indicate that the amount and structure of antibacterial layer is dependent on roughness and wettability of textile surface. The rougher and more hydrophilic is the material, the more ZnO were deposited. All studied textiles show significant bactericidal activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). A possible mechanism and difference in sensitivity between Gram-negative and Gram-positive bacteria to ZnO is discussed. Considering that antibacterial activity of ZnO is caused by Reactive Oxygen Species (ROS) generation, an influence of surface to volume ratio and crystalline parameters is also discussed.

Irena Maliszewska

Papers

Production of exogenous lipases by bacteria, fungi, and actinomycetes

Azaanalogues of ebselen as antimicrobial and antiviral agents: synthesis and properties.

Green Synthesis and Characterization of Silver Nanoparticles Using Ascomycota Fungi Penicillium nalgiovense AJ12

Production and some properties of lipase from penicillium citrinum

Deposition of Zinc Oxide on Different Polymer Textiles and Their Antibacterial Properties.