Soil Chemical Analysis

Secret History: Return of the Black Death Channel 4, 7-8pm In 1348 the Black Death swept through London, killing people within days of the appearance of their first symptoms. Exactly how many died, and why, has long been a mystery. This Secret History documentary follows experts as they pick through the evidence and reveal why the plague killed on such a scale. And they ask, what might be coming next?

Medscape

Short protocols in molecular biology

During the past few years, silver nanoparticles (AgNPs) became one of the most investigated and explored nanotechnology-derived nanostructures, given the fact that nanosilver-based materials proved to have interesting, challenging, and promising characteristics suitable for various biomedical applications. Among modern biomedical potential of AgNPs, tremendous interest is oriented toward the therapeutically enhanced personalized healthcare practice. AgNPs proved to have genuine features and impressive potential for the development of novel antimicrobial agents, drug-delivery formulations, detection and diagnosis platforms, biomaterial and medical device coatings, tissue restoration and regeneration materials, complex healthcare condition strategies, and performance-enhanced therapeutic alternatives. Given the impressive biomedical-related potential applications of AgNPs, impressive efforts were undertaken on understanding the intricate mechanisms of their biological interactions and possible toxic effects. Within this review, we focused on the latest data regarding the biomedical use of AgNP-based nanostructures, including aspects related to their potential toxicity, unique physiochemical properties, and biofunctional behaviors, discussing herein the intrinsic anti-inflammatory, antibacterial, antiviral, and antifungal activities of silver-based nanostructures.

/pdf/biomedical-applications-of-silver-nanoparticles-an-up-to-1rjmcs1uea.pdf

Biomedical Applications of Silver Nanoparticles: An Up-to-Date Overview

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.

Biodegradable and active nanocomposite pouches reinforced with silver nanoparticles for improved packaging of chicken sausages

Medical device related infections caused by coagulase-negative staphylococci (CoNS) are difficult to treat mainly because of the increased bacterial genetic tolerance to antibiotics and its notorious biofilm formation property which has been reported to be achieved through a wide range of mechanisms. Current study is the demonstration of persistent antibiotic delivering potential and broad spectrum of activity of nanoantibiotic combinations designed from gold nanoparticles in conjugation with known antimicrobial agents. Such formulations are of potential applications as surface engineering agents on medical devices to prevent device mediated infection caused by pathogens like CoNS. For this, highly stable gold nanoparticles fabricated by a Bacillus sp. were functionalized with ciprofloxacin, gentamycin, rifampicin, and vancomycin and these nanoparticle-antibiotic conjugates were studied for its effectiveness against selected CoNS like Staphylococcus epidermidis and Staphylococcus haemolyticus. Very interestingly, the designed conjugates were identified to have a profound antibacterial efficiency compared to pure antibiotic and AuNPs. Thus, the result of the study is with highly significant medical applications as the test organisms used are emerging opportunistic pathogens.

https://link.springer.com/content/pdf/10.1007%2Fs13404-015-0162-4.pdf

Effect of biofabricated gold nanoparticle-based antibiotic conjugates on minimum inhibitory concentration of bacterial isolates of clinical origin

One-step synthesis of eco-friendly boiled rice starch blended polyvinyl alcohol bionanocomposite films decorated with in situ generated silver nanoparticles for food packaging purpose.

Aims

The study mainly aimed quantitative analysis of IAA produced by endophytic bacteria under various conditions including the presence of extract from Piper nigrum Analysis of genetic basis of IAA production was also conducted by studying the presence and diversity of the ipdc gene among the selected isolates



Materials and methods

Five endophytic bacteria isolated previously from P nigrum were used for the study The effect of temperature, pH, agitation, tryptophan concentration and plant extract on modulating IAA production of selected isolates was analysed by colorimetric method Comparative and quantitative analysis of IAA production by colorimetric isolates under optimal culture condition was analysed by HPTLC method Presence of ipdc gene and thereby biosynthetic basis of IAA production among the selected isolates were studied by PCR-based amplification and subsequent insilico analysis of sequence obtained



Conclusions

Among the selected bacterial isolates from P nigrum, isolate PnB 8 (Klebsiella pneumoniae) was found to have the maximum yield of IAA under various conditions optimized and was confirmed by colorimetric, HPLC and HPTLC analysis Very interestingly, the study showed stimulating effect of phytochemicals from P nigrum on IAA production by endophytic bacteria isolated from same plant



Significance and Impact of the Study

This study is unique because of the selection of endophytes from same source for comparative and quantitative analysis of IAA production under various conditions Study on stimulatory effect of phytochemicals on bacterial IAA production as explained in the study is a novel approach Studies on molecular basis of IAA production which was confirmed by sequence analysis of ipdc gene make the study scientifically attractive Even though microbial production of IAA is well known, current report on detailed optimization, effect of plant extract and molecular confirmation of IAA biosynthesis is comparatively novel in its approach

Studies on the factors modulating indole‐3‐acetic acid production in endophytic bacterial isolates from Piper nigrum and molecular analysis of ipdc gene

Multiple antibiotic resistance and diverse mechanisms for biofilm formation make Coagulase Negative Staphylococci (CoNS) to cause infections associated with insertion of medical devices. As the infectious life style of CoNS pose difficult to treat conditions, materials with multitargeted antimicrobial effect can offer promising ways to modify the surface of devices to limit microbial growth. The broad spectrum of antimicrobial properties shown by silver nanoparticles (AgNPs) make it as an excellent candidate to act on device surface as persistent antimicrobial structures. In the current study, AgNPs assembled by soil bacteria under visible light at room temperature were analysed for its physical properties by UV–Vis spectroscopy, FTIR, SEM, HR-TEM and EDS and they also showed significant antimicrobial and antibiofilm properties against selected members of CoNS like Staphylococcus epidermidis and Staphylococcus haemolyticus. Very interestingly, further analysis on antibacterial mechanism of AgNPs showed their remarkable ability to cause disorganization of bacterial cell membrane. Further, surface engineering application of AgNPs on urinary catheter showed its excellent potential to prevent the attachment and colonization of CoNS which make result of study with significantly novel medical applications.

E. K. Radhakrishnan

Papers

Biodegradable and active nanocomposite pouches reinforced with silver nanoparticles for improved packaging of chicken sausages

Effect of biofabricated gold nanoparticle-based antibiotic conjugates on minimum inhibitory concentration of bacterial isolates of clinical origin

One-step synthesis of eco-friendly boiled rice starch blended polyvinyl alcohol bionanocomposite films decorated with in situ generated silver nanoparticles for food packaging purpose.

Studies on the factors modulating indole‐3‐acetic acid production in endophytic bacterial isolates from Piper nigrum and molecular analysis of ipdc gene

Inhibitory effect of silver nanoparticle fabricated urinary catheter on colonization efficiency of Coagulase Negative Staphylococci