scholarly journals Key Physicochemical Determinants in the Antimicrobial Peptide RiLK1 Promote Amphipathic Structures

2021 ◽  
Vol 22 (18) ◽  
pp. 10011
Author(s):  
Lucia Falcigno ◽  
Gabriella D’Auria ◽  
Gianna Palmieri ◽  
Marta Gogliettino ◽  
Bruna Agrillo ◽  
...  
Keyword(s):  
Bacterial Resistance ◽  
High Antimicrobial Activity ◽  
Self Assembling ◽  
Atomic Force ◽  
New Antibiotics ◽  
Physicochemical Features ◽  
Low Costs ◽  
Low Cytotoxicity ◽  
Improved Performance ◽  
Net Positive Charge

Antimicrobial peptides (AMPs) represent a skilled class of new antibiotics, due to their broad range of activity, rapid killing, and low bacterial resistance. Many efforts have been made to discover AMPs with improved performances, i.e., high antimicrobial activity, low cytotoxicity against human cells, stability against proteolytic degradation, and low costs of production. In the design of new AMPs, several physicochemical features, such as hydrophobicity, net positive charge, propensity to assume amphipathic conformation, and self-assembling properties, must be considered. Starting from the sequence of the dodecapeptide 1018-K6, we designed a new 10-aminoacid peptide, namely RiLK1, which is highly effective against both fungi and Gram-positive and -negative bacteria at low micromolar concentrations without causing human cell cytotoxicity. In order to find the structural reasons explaining the improved performance of RiLK1 versus 1018-K6, a comparative analysis of the two peptides was carried out with a combination of CD, NMR, and fluorescence spectroscopies, while their self-assembling properties were analyzed by optical and atomic force microscopies. Interestingly, the different spectroscopic and microscopic profiles exhibited by the two peptides, including the propensity of RiLK1 to adopt helix arrangements in contrast to 1018-K6, could explain the improved bactericidal, antifungal, and anti-biofilm activities shown by the new peptide against a panel of food pathogens.

Ingan Quantum Dots Fabricated On Aigan Surfaces -Growth Mechanism And Optical Propertiesh-

1997 ◽  
Vol 482 ◽  
Author(s):  
H. Hirayama ◽  
S. Tanaka ◽  
P. Ramvall ◽  
Y. Aoyagi
Keyword(s):  
Quantum Dots ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Energy Shift ◽  
Organic Chemical ◽  
Self Assembling ◽  
Atomic Force ◽  
Peak Energy ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

AbstractWe demonstrate photoluminescence from self- assembling InGaN quantum dots (QDs), which are artificially fabricated on AlGaN surfaces via metal- organic chemical vapor deposition. InGaN QDs are successfully fabricated by the growth mode transition from step- flow to three dimensional island formation by using anti-surfactant silicon on AlGaN surface. The diameter and height of the fabricated InGaN QDs are estimated to be ˜10nm and ˜5nm, respectively, by an atomic- force- microscope (AFM). Indium mole fraction of InxGal−x N QDs is controlled from x=˜0.22 to ˜0.52 by varying the growth temperature of QDs. Intense photoluminescence is observed even at room temperature from InGaN QDs embedded with the GaN capping layers. In addition, the temperature- dependent energy shift of the photoluminescence peak- energy shows a localization behavior.

The Development of Antibiotics Based on Nanostructured Manganese Oxide; Understanding Mechanism from Fundamental Aspects to Application

2020 ◽  
Vol 20 (12) ◽  
pp. 7618-7628
Author(s):  
Ayesha Taj ◽  
Rabisa Zia ◽  
Sadaf Hameed ◽  
Adnan Mujahid ◽  
Asma Rehman ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Manganese Oxide ◽  
Bacterial Resistance ◽  
Bacterial Species ◽  
Spherical Particles ◽  
X Ray ◽  
Atomic Force ◽  
Uv Visible ◽  
Scanning Electron

The emergence of bacterial resistance to currently available antibiotics emphasized the urgent need for new antibacterial agents. Nanotechnology-based approaches are substantially contributing to the development of effective and better-formulated antibiotics. Here, we report the synthesis of stable manganese oxide nanostructures (MnO NS) by a facile, one-step, microwave-assisted method. Asprepared MnO NS were thoroughly characterized by atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), dynamic light scattering (DLS), UV-Visible spectroscopy and X-ray powder diffraction (XRD). UV-Visible spectra give a sharp absorption peak at a maximum wavelength of 430 nm showed surface plasmon resonance (SPR). X-ray diffraction (XRD) profile demonstrated pure phase and crystalline nature of nanostructures. Morphological investigations by a scanning electron microscope showed good dispersity with spherical particles possessing a size range between 10–100 nm. Atomic force microscope data exhibited that the average size of MnO NS can be controlled between 25 nm to 150 nm by a three-fold increment in the amount of stabilizer (o-phenylenediamine). Antimicrobial activity of MnO NS on both gram-positive (Bacillus subtilis) and gram-negative (Escherichia coli) bacterial strains showed that prepared nanostructures were effective against microorganisms. Further, this antibacterial activity was found to be dependent on nanoparticles (NPs) size and bacterial species. These were more effective against Bacillus subtilis (B. subtilis) as compared to Escherichia coli (E. coli). Considering the results together, this study paves the way for the formulation of similar nanostructures as effective antibiotics to kill other pathogens by a more biocompatible platform. This is the first report to synthesize the MnO NS by green approach and its antibacterial application.

Surface modification via self-assembling large cations for improved performance and modulated hysteresis of perovskite solar cells

2019 ◽  
Vol 7 (12) ◽  
pp. 6793-6800 ◽  
Author(s):  
Tongle Bu ◽  
Jing Li ◽  
Wenchao Huang ◽  
Wenxin Mao ◽  
Fei Zheng ◽  
...  
Keyword(s):  
Surface Modification ◽  
Solar Cells ◽  
Perovskite Solar Cells ◽  
High Quality ◽  
Self Assembling ◽  
Improved Performance

Novel surface modification of self-assembling large cations enables the achievement of high quality perovskite films for hysteresis-free and stable solar cells with an optimized efficiency over 20%.

Self-assembling of Z-α-pyridylcinnamic acid molecules over polycrystalline Ag and Au surfaces followed by FT-IR and atomic force microscopies

2011 ◽  
Vol 993 (1-3) ◽  
pp. 67-72
Author(s):  
K. Csankó ◽  
M. Darányi ◽  
G. Kozma ◽  
Á. Kukovecz ◽  
Z. Kónya ◽  
...  
Keyword(s):  
Self Assembling ◽  
Atomic Force ◽  
Ft Ir

scholarly journals Novel Group of Leaderless Multipeptide Bacteriocins from Gram-Positive Bacteria

2016 ◽  
Vol 82 (17) ◽  
pp. 5216-5224 ◽  
Author(s):  
Kirill V. Ovchinnikov ◽  
Hai Chi ◽  
Ibrahim Mehmeti ◽  
Helge Holo ◽  
Ingolf F. Nes ◽  
...  
Keyword(s):  
Amino Acids ◽  
Antimicrobial Activity ◽  
Bacterial Resistance ◽  
Raw Milk ◽  
Peptide Sequencing ◽  
Homology Search ◽  
Resistant Bacteria ◽  
Content Type ◽  
New Antibiotics ◽  
Inhibitory Spectrum

ABSTRACTFrom raw milk we found 10Lactococcus garvieaeisolates that produce a new broad-spectrum bacteriocin. Though the isolates were obtained from different farms, they turned out to possess identical inhibitory spectra, fermentation profiles of sugars, and repetitive sequence-based PCR (rep-PCR) DNA patterns, indicating that they produce the same bacteriocin. One of the isolates (L. garvieaeKS1546) was chosen for further assessment. Purification and peptide sequencing combined with genome sequencing revealed that the antimicrobial activity was due to a bacteriocin unit composed of three similar peptides of 32 to 34 amino acids. The three peptides are produced without leader sequences, and their genes are located next to each other in an operon-like structure, adjacent to the genes normally involved in bacteriocin transport (ABC transporter) and self-immunity. The bacteriocin, termed garvicin KS (GarKS), showed sequence homology to four multipeptide bacteriocins in databases: the known staphylococcal aureocin A70, consisting of four peptides, and three unannotated putative multipeptide bacteriocins produced byBacillus cereus. All these multipeptide bacteriocin loci show conserved genetic organization, including being located adjacent to conserved genetic determinants (Cro/cI and integrase) which are normally associated with mobile genetic elements or genome rearrangements. The antimicrobial activity of all multipeptide bacteriocins was confirmed with synthetic peptides, and all were shown to have broad antimicrobial spectra, with GarKS being the most active of them. The inhibitory spectrum of GarKS includes important pathogens belonging to the generaStaphylococcus,Bacillus,Listeria, andEnterococcus.IMPORTANCEBacterial resistance to antibiotics is a very serious global problem. There are no new antibiotics with novel antimicrobial mechanisms in clinical trials. Bacteriocins use antimicrobial mechanisms different from those of antibiotics and can kill antibiotic-resistant bacteria, but the number of bacteriocins with very broad antimicrobial spectra is very small. In this study, we have found and purified a novel three-peptide bacteriocin, garvicin KS. By homology search, we were able to find one known and three novel sequence-related bacteriocins consisting of 3 or 4 peptides. None of the peptides has modified amino acids in its sequence. Thus, the activity of all bacteriocins was confirmed with chemically synthesized peptides. All of them, especially garvicin KS, have very broad antibacterial spectra, thus representing a great potential in antimicrobial applications in the food industry and medicine.

Self-assembling Janus dendritic polymer for gene delivery with low cytotoxicity and high gene transfection efficiency

2016 ◽  
Vol 4 (39) ◽  
pp. 6462-6467 ◽  
Author(s):  
Sheng-Gang Ding ◽  
Lei Yu ◽  
Long-Hai Wang ◽  
Lin-Ding Wang ◽  
Zhi-Qiang Yu ◽  
...  
Keyword(s):  
Gene Delivery ◽  
Transfection Efficiency ◽  
Gene Transfection ◽  
Dendritic Polymer ◽  
Self Assembling ◽  
High Gene ◽  
Low Cytotoxicity

Polycations have high DNA condensing ability, low immunogenicity, and great adaptability, which make them promising for gene delivery.

Preparation and Time Resolved Photoluminescence of Nanoscale InP Islands in In0.48Ga0.52P

1995 ◽  
Vol 379 ◽  
Author(s):  
K. Eberl ◽  
A. Kurtenbach ◽  
K. HÄusler ◽  
F. Noll ◽  
W.W. RÜhle
Keyword(s):  
Lattice Mismatch ◽  
Excitation Power ◽  
Buffer Layers ◽  
Time Resolved ◽  
Force Microscopy ◽  
Self Assembling ◽  
Atomic Force ◽  
Transmission Electron ◽  
Decay Times ◽  
Time Resolved Photoluminescence

ABSTRACTNanoscale InP islands are formed during InP/In0 48Ga0.52P heteroepitaxy due to the lattice mismatch of about 3.7%. The samples are prepared by solid source molecular beam epitaxy on (001) GaAs substrate. Atomic force microscopy measurements show that the size of the islands is typically 15 to 50 nm in diameter and about 5 to 10 nm high depending on the nominally deposited InP layer thickness, which is between 1 and 7.5 monolayers. Transmission electron micrographs show the coherent incorporation into the In0.48Ga0.52P matrix for InP islands with 2.5 monolayers. Resonantly excited time-resolved photoluminescence (PL) measurements of the self assembling InP dots are performed for optical characterisation. The decay times are typically 400 ps. The dependence on excitation power and temperature indicates the quantum dot nature of the InP islands. Finally a pronounced alignment of the InP islands is obtained on strained In0.61Ga0.39P buffer layers.

scholarly journals Discovery and development of new antimicrobial agents.

1990 ◽  
Vol 3 (1) ◽  
pp. 13-31 ◽  
Author(s):  
T D Gootz
Keyword(s):  
Bacterial Resistance ◽  
Antimicrobial Agents ◽  
Bacterial Cells ◽  
Beta Lactams ◽  
Resistance Development ◽  
Safety Testing ◽  
The Past ◽  
Body Of Knowledge ◽  
New Antibiotics ◽  
The Impact

The unprecedented growth in the number of new antibiotics over the past two decades has been the result of extensive research efforts that have exploited the growing body of knowledge describing the interactions of antibiotics with their targets in bacterial cells. Information gained from one class of antimicrobial agents has often been used to advance the development of other classes. In the case of beta-lactams, information on structure-activity relationships gleaned from penicillins and cephalosporins was rapidly applied to the cephamycins, monobactams, penems, and carbapenems in order to discover broad-spectrum agents with markedly improved potency. These efforts have led to the introduction of many new antibiotics that demonstrate outstanding clinical efficacy and improved pharmacokinetics in humans. The current review discusses those factors that have influenced the rapid proliferation of new antimicrobial agents, including the discovery of new lead structures from natural products and the impact of bacterial resistance development in the clinical setting. The development process for a new antibiotic is discussed in detail, from the stage of early safety testing in animals through phase I, II, and III clinical trials.

scholarly journals Silver Nanoparticle-Based Paper Packaging to combat Black Anther Disease in Orchid Flowers

2018 ◽  
Author(s):  
Bang-on Nokkrut ◽  
Sawitree Pisuttipiched ◽  
Somwang Khantayanuwong ◽  
Buapan Puangsin
Keyword(s):  
Water Resistance ◽  
Reduction Method ◽  
Chemical Reduction ◽  
Metal Nanoparticle ◽  
Chemical Reduction Method ◽  
High Antimicrobial Activity ◽  
Coating Solution ◽  
Atomic Force ◽  
Vis Spectroscopy ◽  
Average Size

Metal nanoparticle has been reported to have a high antimicrobial activity against fungi, bacteria, and yeasts. In this study, silver nanoparticles (AgNPs) were synthesized using a chemical reduction method, at 90 oC, and used as an antifungal coating in paper packaging, to control the growth of C. gloeosporioides in cut orchid flowers during shipping. AgNPs were characterized by UV-Vis spectroscopy and atomic force microscope (AFM). The results indicated that the shape of AgNPs was spherical and homogenous with an average size of 47 nm. Twenty and 50 particles per million (ppm) concentration of AgNPs, mixed with starch, were prepared as the coating solution. The paper coated with 50 ppm AgNPs exhibited a significant antifungal activity against C. gloeosporioides compared to 20 ppm AgNPs coating. The AgNPs coated paper had a better water resistance and mechanical properties compared to paper without coating. We observed a significant reduction in the number of anthers, of orchid inflorescences, infected by C. gloeosporioides, when stored in the coated boxes. The current study demonstrates that paper boxes coated with AgNPs are a potential solution to control the infection of C. gloeosporioides in the storage of cut orchid flowers.

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