Presence Of Biological Molecules Research Articles

Green synthesis of non-cytotoxic silver nanoparticles using Solanum nigrum leaves extract with antibacterial properties

Green synthesizes of silver nanoparticles is a promising method in material science and nanotechnology today. Silver nanoparticles (AgNP) were synthesized using a high-efficiency, cost-effective green and simple method at room temperature using Solanum nigrum leaves extract. The biosynthesized AgNP was validated and classified using spectroscopy profiles from ultraviolet-visible spectroscopy, scanning electron microscope, Fourier-transform infrared spectroscopy and x-ray diffraction. FTIR spectra indicated the presence of biological molecules in AgNP synthesis and UV-visible spectra revealed a surface resonance peak of 420 nm corresponding to AgNP formation. The antimicrobial potential of these synthesized nanoparticles is evaluated against the bacteria Escherichia coli (MCC 2079) and Staphylococcus aureus (MCC 2408), both of which are important foodborne pathogens. Ciprofloxacin and Clotrimazole were used as positive controls antibiotic. The nanoparticles were shown to have strong antibacterial efficacy against the strains examined. Their antibacterial function allows them to be included in antimicrobial formulations. By using the MTT assay, the biocompatibility of Solanum nigrum silver nanoparticles were found non-toxic to mouse fibroblast cell lines (L929 is one of the first in continuous culture to be created. The L strain was generated from a male C3H mouse's usual subcutaneous areolar and adipose tissue.) at lower concentrations.

Biosynthesis, characterization, bactericidal and sporicidal activity of silver nanoparticles using the leaves extract of Litchi chinensis

Biosynthesis of silver nanoparticles (AgNPs) using plant extracts has become a promising alternative to the conventional chemical synthesis approach. In this study, cost-effective synthesis of AgNPs was attempted using leaves extract of Litchi chinensis. Bio-reduction reaction for the synthesis of NPs was checked by confirming the presence of AgNPs in solution by UV-vis spectrophotometry and with further characterization by fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Surface plasmon resonance (SPR) band showed absorption peak at 422 nm indicating the formation of AgNPs, and FTIR spectra confirmed the presence of biological molecules involved in AgNPs synthesis. TEM analysis revealed the spherical shape of AgNPs with particle size distribution in a range of 5–15 nm. Further, the biosynthesized AgNPs showed significant bactericidal and sporicidal activity against model spore former Bacillus subtilis. AgNPs at concentrations ranging from 25 to 100 µg/mL showed bactericidal activity with inhibition zone ranging from 4–19 mm and sporicidal activity at 100–200 µg/mL in a range of 4.46–61.6% with an exposure time of 2–8 h. These findings exhibit distinctive potential of biogenic AgNPs for their efficient use in developing novel bactericidal and sporicidal agent against spore forming bacilli.

Racemisation in Chemistry and Biology.

The two enantiomers of a compound often have profoundly different biological properties and thus their liability to racemisation in aqueous solutions is an important piece of information. The authors reviewed the available data concerning the process of racemisation in vivo, in the presence of biological molecules (e.g., racemase enzymes, serum albumin, cofactors and derivatives) and under purely chemical but aqueous conditions (acid, base and other aqueous systems). Mechanistic studies are described critically in light of reported kinetic data. The types of experimental measurement that can be used to effectively determine rate constants of racemisation in various conditions are discussed and the data they provide is summarised. The proposed origins of enzymatic racemisation are presented and suggest ways to promote the process that are different from processes taking place in bulk water. Experimental and computational studies that provide understanding and quantitative predictions of racemisation risk are also presented.

Novel synthetic approach to near-infrared heptamethine cyanine dyes and spectroscopic characterization in presence of biological molecules

Abstract Two near-infrared symmetric heptamethine cyanine dyes, containing integrated chlorosubstituted cyclohexenyl ring were obtained via a novel synthetic approach, using mild conditions at room temperature. UV–vis and fluorescence properties of the dyes were evaluated in organic solutions varying solvent polarity. Further spectral studies illustrating their application as potential labels for biological molecules, were reported in the presence of deoxyribonucleic acid (DNA), bovine serum albumin (BSA), and phospholipids (PC). The dyes undergo H-type intramolecular complexation between the two cyanine subunits when free in buffer. Absorption studies show that binding of cyanines to DNA, BSA and lipid membranes leads to the red shift in the H-aggregates peak with appearance of monomeric and dimeric dye species pointing to the disaggregation of the dyes under study in the presence of biological molecules. The fact that the decrease of liposome-induced cyanine aggregation was more pronounced in the zwitterionic phosphatidylcholine bilayer, suggests that the disruption of highly organized molecular arrangements are most likely electrostatically-controlled.

X-ray and Neutron Scattering of Water.

This review article focuses on the most recent advances in X-ray and neutron scattering studies of water structure, from ambient temperature to the deeply supercooled and amorphous states, and of water diffusive and collective dynamics, in disparate thermodynamic conditions and environments. In particular, the ability to measure X-ray and neutron diffraction of water with unprecedented high accuracy in an extended range of momentum transfers has allowed the derivation of detailed O-O pair correlation functions. A panorama of the diffusive dynamics of water in a wide range of temperatures (from 400 K down to supercooled water) and pressures (from ambient up to multiple gigapascals) is presented. The recent results obtained by quasi-elastic neutron scattering under high pressure are compared with the existing data from nuclear magnetic resonance, dielectric and infrared measurements, and modeling. A detailed description of the vibrational dynamics of water as measured by inelastic neutron scattering is presented. The dependence of the water vibrational density of states on temperature and pressure, and in the presence of biological molecules, is discussed. Results about the collective dynamics of water and its dispersion curves as measured by coherent inelastic neutron scattering and inelastic X-ray scattering in different thermodynamic conditions are reported.

ChemInform Abstract: Modular and Orthogonal Synthesis of Hybrid Polymers and Networks

AbstractReview: 219 refs.

Direct Colorimetric Biosensors from Polydiacetylenes

Polydiacetylenes (PDAs) have gained much interest in recent years because of their distinctive chromatic transition property. The PDA molecules can be self-assembled into thin films or vesicles that could undergo blue-red transformations in response to different stimuli, like temperature, pH, and the presence of biological molecules. Due to this unique chromatic property, PDA materials have emerged as an attractive option for biosensing applications. Functionalized PDA has been used as a platform for detection of biological analytes, including viruses, microorganisms, and proteins. In this paper, we will review the formation of PDA films and vesicles, their optical properties, and their potential applications as biosensors.

Polydiacetylene as a Biosensor: Fundamentals and Applications in the Food Industry

Biosensors offer the potential for real-time pathogen detection. Polydiacetylene (PDA) is an ideal choice for use as a sensor due to its unique optical properties. PDA molecules can form thin films or vesicles that change color from deep blue to red in response to different stimuli, like temperature, pH, and the presence of biological molecules. PDA films and vesicles have been proven to be promising devices for the detection of bacteria and bacterial toxins. Langmuir troughs (for films) and microcalorimetry (for vesicles) are among the many techniques used to characterize PDA films and vesicles. In order to enable more applications of PDA films, it is imperative to elucidate and gain a deeper understanding of the molecular interactions associated with their color change. In addition, it is necessary to transfer the PDA film onto a solid support like plastic in order to incorporate PDA biosensors into an intelligent packaging system. Through the use of such a system, consumers can monitor food quality, thereby preventing foodborne outbreaks. In this review, we discuss the formation of PDA films and vesicles, their characteristics, and their potential applications as biosensors. The possibility to incorporate PDA biosensors into an intelligent packaging system to be used in the food industry is also explored.

Role of fetal bovine serum in the prevention of calcification in biological fluids

The presence of biological molecules can significantly regulate the crystallization of inorganic hard tissues in living organisms. The purpose of this study is to investigate the influence of fetal bovine serum (FBS) on the precipitation and phase transformation of calcium phosphate. The precipitation of large-sized calcium phosphate in RPMI1640, a widely used cell culture, is readily induced by an addition of calcium solution. However, FBS can retard this unexpected calcification process in RPMI1640. Using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy, it is revealed that FBS can suppress the aggregation of nano-calcium phosphate clusters. Furthermore, FBS can also retard the phase transformation of unstable amorphous calcium phosphate to crystallized hydroxyapatite in biological milieus. The results show that FBS has a very strong negative influence on the precipitation of calcium phosphate, which plays an important role in stabilizing the blood compositions. This study also implies the application of FBS in the treatment of pathological calcification.

Fluorescent Properties of Pentamethine Cyanine Dyes with Cyclopentene and Cyclohexene Group in Presence of Biological Molecules

A series of pentamethine cyanine dyes with cyclohexene or cyclopentene group in polymethyne chain, assumed as DNA groove-binders, were studied as fluorescent probes for nucleic acids as well as for native and denatured proteins. It was revealed that the presence of methyl or dimethyl substituent in 5 position of the cyclohexene group hinders the formation of dye-DNA fluorescent complex, while the methyl substituent in 2 position leads to the increasing of the dye-DNA complex fluorescence intensity. The dyes SL-251, SL-1041, and SL-1046 containing methyl group in the 2 position of the cyclic group, are reported as bright DNA-sensitive dyes. The study of the dyes DNA-binding specificity demonstrated significant AT-preference that points to the groove-binding interaction mode. At the same time, the dyes SL-251, SL-377, and SL-957 with the 2-methyl substituted cyclohexene group were shown to be sensitive fluorescent dyes both for nonspecific (in SDS presence) proteins detection and for native BSA.

Atomic force microscope chamber for in situ studies of ice

To investigate the surface morphologies of biological systems in a controlled gaseous environment (e.g., the temperature, humidity and composition), most commercial atomic force microscopes require modification. We have designed a double-jacketed environmental chamber specifically for a Nanoscope IIIa (Digital Instruments, Santa Barbara, CA) force microscope. We use cold nitrogen and thermoelectric devices to control the temperature in the chamber; the nitrogen simultaneously serves to create an inert environment. We have also designed a temperature controlled sample stage utilizing thermoelectric devices for fine temperature regulation. A variation of this sample stage allows us to image samples in fluids at cold temperatures with an O-ringless configuration. The relative humidity within the chamber is also measured with commercially available relative humidity sensors. We investigate the surface morphology of ice Ih in its pure phase and shall extend the study to ice in the presence of biological molecules, such as antifreeze proteins. We present a detailed description of our design and our first images of polycrystalline ice and single crystals of ice grown in situ from the vapor.

Simulating arterial wall calcification in vitro: biomimetic crystallization of calcium phosphates under controlled conditions.

A method to simulate the biological and pathological crystallization of calcium phosphate in vitro is presented. The pathological crystallization of calcium phosphates during atherosclerosis is still poorly understood as it depends on a variety of external factors, e.g., the presence of biological molecules that act as crystallization promoters or inhibitors. A computer-controlled double-diffusion device is presented that permits crystallization under constant external conditions (constant pH, constant concentrations of Ca2+ and PO4(3-)). The crystallization of hydroxyapatite occurs in a well-defined way. The presence of additives (cholesterol, magnesium) distinctively alters the morphology of the crystals. The simulation of pathological crystallization as in atherosclerosis is possible if the external conditions are kept strictly constant during the experiment. In order to obtain a meaningful insight into biological crystallization, this approach is essential as otherwise the external conditions change continuously during the experiment. The effect of additives can be conveniently studied.