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2 Coatings for Medical Applications
Published in Peerawatt Nunthavarawong, Sanjay Mavinkere Rangappa, Suchart Siengchin, Mathew Thoppil-Mathew, Antimicrobial and Antiviral Materials, 2022
Many studies show that gram-positive bacteria were more resistant to photocatalytic disinfection on TiO2 than gram-negative bacteria due to differences in the cell wall structure. Gram-positive bacteria have a thicker peptidoglycan layer and no outer membrane, whereas gram-negative bacteria have three layers of the cell wall; an inner membrane, a thin peptidoglycan layer, and an outer membrane [16, 22, 33-38]. There are some examples of gram-positive bacteria killed by photocatalytic disinfection on TiO2. For example, TiO2 suspension was studied to kill gram-positive bacteria as follows; Lactobacillus acidophilus [39-43], Listeria monocytogenes [22], Bacillus cereus [44], MRSA and Staphylococcus saprophyticus [45]. For TiO2 thin film application, there were some examples of studies as follows; Clostridium perfringens spores NCIMB 6125 [9], Staphylococcus aureus [46], Lactococcus lactis 411 [38], and Bacillus thuringiensis [47]. In addition, there were few TiO2 coating applications for killing organisms, for example, Actinobacillus actinomycetemcomitans [48] and Streptococcus iniae [49]. Nagame and colleagues [50] studied in killed Streptococcus cricetus by Kobe Steel TiO2 99.98% anatase. Tsuang and colleagues [29] studied the effect of TiO2 on orthopedic implants, and they found that TiO2 was the ability to kill Enterococcus hirae. TiO2 can kill gram-positive bacteria by photocatalytic disinfection [2].
Bacterial Detection with Magnetic Nanoparticles
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Nayeem A. Mulla, Raghvendra A. Bohara, Shivaji H. Pawar
Fundamentals of morphology, molecular chemistry, and surface physiochemical are important considerations while detecting bacterial species. With respect to conventional sense of biology, bacteria are known as microscopic organisms, ranging a few micrometers in length and of various different kinds. They are unicellular, prokaryotic in nature with no internal organization, and multiply by undergoing fission. They have different shapes like rod, spherical, and cuboidal. They can be found either singly or in pairs or even as chains or clusters. They have a single chromosome with a closed circle of double-stranded DNA [9]. Sometimes, they possess characteristic appendages like flagella. The cell wall is rigid and made up of phospholipid bilayers. Bacteria can be categorized on different bases such as by staining (e.g., Gram-positive, Gram-negative), culturing requirements (aerobic, anaerobic), etc. Mostly, they are recognized based on Gram staining. Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acid. In contrast, Gram-negative bacteria have a relatively thin cell wall consisting few layers of peptidoglycan surrounded by a second lipid layer containing lipopolysaccharides and lipoproteins [10].
Nanoparticles of Marine Origin and Their Potential Applications
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Fatemeh Sedaghat, Morteza Yousefzadi, Reza Sheikhakbari-Mehr
AgNPs exhibit potential antimicrobial properties against infectious microbes such as Escherichia coli, Bacillus subtilis, Vibrio cholerae, Pseudomonas aeruginosa, and Staphylococcus aureus. The application of nanomaterials as new antimicrobials provides novel modes of action on different cellular targets in comparison with existing antibiotics. Multiple drug resistance to traditional antibiotics has created a great requirement for the development of new antimicrobial agents. Bacteria are classified as gram-negative or gram-positive. The peptidoglycan is the key component of the bacterial cell wall. Gram-negative bacteria have only a thin peptidoglycan layer (~2–3 nm) between their two membranes, while Gram-positive bacteria lack the outer membrane (substituted by a thick peptidoglycan layer). Smaller sized NPs disrupt the function of the membrane (such as permeability or respiration) by attaching to its surface and subsequently, penetrating the cell and cause further damage by interacting with the DNA. The antimicrobial properties of Ag encourage its use in biomedical applications, animal husbandry, food packaging, water purification, cosmetics, clothing, and numerous household products. Now, Ag is the engineered nanomaterial most commonly used in consumer products. Clothing, respirators, household water filters, contraceptives, antibacterial sprays, cosmetics, detergent, dietary supplements, cutting boards, socks, shoes, cell phones laptop keyboards, and toys are among the retail products that purportedly exploit the antimicrobial properties of Ag nanomaterials. Several researchers investigated the antimicrobial efficacy against different bacterial and fungal pathogens [Ramkumara et al., 2016; Franci et al., 2015; Prabhu and Poulose, 2012].
Design and synthesis of silver nanoparticle anchored poly(ionic liquid)s mesoporous for controlled anticancer drug delivery with antimicrobial effect
Published in International Journal of Environmental Health Research, 2022
Ehsan Aliakbari, Yahya Nural, Reza Eghdam Zamiri, Erdal Yabalak, Mehri Mahdavi, Vahid Yousefi
E.coli is a Gram-negative bacterium and S. aureus is a Gram-positive bacterium, and their difference is related to their structure. Gram-positive bacteria have a thick peptidoglycan network cell wall; Gram-negative bacteria have a thin peptidoglycan cell wall and an outer phospholipid bilayer membrane (Beveridge 2001). The fact that the MIC and MBC values obtained are the same for E. coli but different for S. aureus can be explained by the fact that the desired drug is stuck between the peptidoglycan strands and cannot pass much, but it easily passes through the phospholipid membrane. As a result, for E. coli, which has a thick phospholipid membrane wall, it passed easily and its MIC and MBC are the same, but in the case of S. aureus, because it has a thin phospholipid membrane wall, but instead has a thick peptidoglycan membrane, and the drug could not penetrate easily.
A Review on Bioflotation of Coal and Minerals: Classification, Mechanisms, Challenges, and Future Perspectives
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Kaveh Asgari, Qingqing Huang, Hamid Khoshdast, Ahmad Hassanzadeh
Gram-negative bacteria refer to a group that cannot absorb violet crystals during Gram staining due to their wall type and outer membrane. In the second stage of Gram staining, when safranin is added, they show a red and pink color. The cell membrane of Gram-negative bacteria has a multi-layered and very complex structure. The inner membrane of Gram-negative bacteria, called the cytoplasmic membrane, is covered with a flat wall of Peptidoglycan (a huge polymer including sugar derivatives and amino acids), to which the outer membrane is attached. Among the Gram-negative bacteria are the fourth group of BV4 bacteria such as Chlamydia, Acidobacteria and Spirochetes and the three main branches of Proteobacteria. Gram-positive bacteria, meanwhile, refers to a group of bacteria that respond positively to Gram staining. The gram-positive bacteria absorb violet crystals by the Peptidoglycan in its wall and appear dark blue or purple. Gram-positive bacteria usually do not have an outer membrane in their cell wall and have a relatively simple cell wall consisting of two to three layers. Staphylococcus is one of the most important Gram-positive bacteria (Gram 1884; Sharma 2001).
A review on the biomedical efficacy of transition metal triazole compounds
Published in Journal of Coordination Chemistry, 2022
Sajjad Hussain Sumrra, Wardha Zafar, Muhammad Imran, Zahid Hussain Chohan
Antibiotic resistance is a complex phenomenon that is the outcome of a number of factors. The foremost factor is the vertiginous decline in research and development of new antibiotics [1]. From the time when the first antibiotic (Penicillin, 1928) was discovered, there has been a “race” between researchers to design and develop new antibiotics and pathogenic bacterial species harboring a number of resistance mechanisms. Antimicrobial resistance in bacteria is alarming, particularly resistance in Gram negative bacteria. In 2017, the World Health Organization (WHO) listed 12 bacteria, which have such a high level of resistance to antibiotics that they represent a threat to human health. Most of these bacteria are Gram negative bacteria. Based on their priority, WHO has grouped and categorized these bacteria as medium, high and critical [2]. It was also stated that 700,000 people are killed by antibiotic resistance each year worldwide. Experts in another report, “Tackling Drug-Resistant Infections Globally: Final Report and Recommendations”, also predicted that drug resistant infections may cause death of 10,000,000 people annually by 2050, beyond the number of deaths due to even cancer or traffic accidents, if no attempts are done to curtail resistance by developing new antibiotics [3].