scholarly journals Genipin-crosslinked chitosan/alginate/alumina nanocomposite gels for 3D bioprinting

2021 ◽  
Author(s):  
Jessica Condi Mainardi ◽  
Kurosch Rezwan ◽  
Michael Maas
Keyword(s):  
Electrostatic Interactions ◽  
Network Formation ◽  
Covalent Binding ◽  
Processing Route ◽  
3D Bioprinting ◽  
Separation And Purification ◽  
Bioactive Materials ◽  
Bacterial Viability ◽  
Crosslinked Chitosan ◽  
The Individual

AbstractImmobilizing microorganisms inside 3D printed semi-permeable substrates can be desirable for biotechnological processes since it simplifies product separation and purification, reducing costs, and processing time. To this end, we developed a strategy for synthesizing a feedstock suitable for 3D bioprinting of mechanically rigid and insoluble materials with embedded living bacteria. The processing route is based on a highly particle-filled alumina/chitosan nanocomposite gel which is reinforced by (a) electrostatic interactions with alginate and (b) covalent binding between the chitosan molecules with the mild gelation agent genipin. To analyze network formation and material properties, we characterized the rheological properties and printability of the feedstock gel. Stability measurements showed that the genipin-crosslinked chitosan/alginate/alumina gels did not dissolve in PBS, NaOH, or HCl after 60 days of incubation. Alginate-containing gels also showed less swelling in water than gels without alginate. Furthermore, E. coli bacteria were embedded in the nanocomposites and we analyzed the influence of the individual bioink components as well as of the printing process on bacterial viability. Here, the addition of alginate was necessary to maintain the effective viability of the embedded bacteria, while samples without alginate showed no bacterial viability. The experimental results demonstrate the potential of this approach for producing macroscopic bioactive materials with complex 3D geometries as a platform for novel applications in bioprocessing.

scholarly journals The effect of avidin-biotin interactions in detection systems for in situ hybridization.

1992 ◽  
Vol 40 (1) ◽  
pp. 135-141 ◽  
Author(s):  
E J Speel ◽  
B Schutte ◽  
F C Ramaekers ◽  
A H Hopman
Keyword(s):  
In Situ Hybridization ◽  
Network Formation ◽  
Transitional Cell ◽  
Fluorescein Isothiocyanate ◽  
Staining Technique ◽  
Dna Probe ◽  
Detection Systems ◽  
Amplification Method ◽  
The Individual

The effect of avidin-biotin interactions in several detection systems for the non-radioactive in situ hybridization (ISH) technique was studied in a model system using a transitional cell carcinoma line and a biotinylated DNA probe. We performed fluorescence ISH to unravel the individual steps in a sensitive and frequently used amplification method which makes use of the alternating cytochemical detection layers of fluorescein isothiocyanate-conjugated avidin (AvFITC) and biotinylated goat anti-avidin (BioGAA) antibodies to detect the hybridized and biotinylated probe. Our experiments revealed that BioGAA antibodies bind with their antigen binding sites and not with their biotin moieties to avidin molecules that have already interacted with the DNA probe. The probable working mechanism of this amplification method is presented in a model. Furthermore, we used a peroxidase staining technique to compare with each other the sensitivity of several other detection systems in which avidin-biotin interactions play an important role, e.g., the avidin-biotinylated peroxidase complex (ABC) system. The experiments show that avidin molecules can not be efficiently used to interconnect two biotinylated molecular layers, since their introduction leads to firmly closed cytochemical networks. Such a closed network is already formed between the hybridized and biotinylated DNA probe and a first detection layer of avidin molecules, as appears from the finding that biotinylated molecules could hardly be coupled to these avidin molecules in a following detection layer. Therefore, the results presented here provide us with new insight into the molecular basis of cytochemical network formation. This will enable us to choose the proper procedures for increasing the sensitivity of ISH detection systems.

scholarly journals Amine-grafted Walnut Shell for Efficient Removal Phosphate and Nitrate from Aqueous Solution

2021 ◽  
Author(s):  
Evans Dovi ◽  
Aaron Albert Aryee ◽  
Jianjun Li ◽  
Zhaohui Li ◽  
Lingbo Qu ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Industrial Effluents ◽  
Environmental Safety ◽  
Water Bodies ◽  
Walnut Shell ◽  
Uptake Capacity ◽  
Effective Removal ◽  
Characterization Studies ◽  
Lower Temperature ◽  
The Individual

Abstract The presence of emerging pollutants such as PO43− and NO3− in water bodies has attracted worldwide concern about their severe effects on water bodies and the health of humankind in general. Therefore, to preserve the health of humankind and environmental safety, it is of the essence that industrial effluents are treated before they are discharged into water bodies. To accomplish this, the walnut shell was functionalized (ACWNS) with amine for effective removal of PO43− and NO3−. Characterization studies of ACWNS were conducted using FTIR, XRD, XPS and BET techniques. Removal of both ions was enhanced at lower temperature (293 K). The maximum uptake capacity of phosphate and nitrate, at 293 K, was 82.2 and 35.7 mg g− 1, respectively. The primary mechanism by which these ions were uptaken onto ACWNS could be electrostatic interactions and hydrogen bonding.Pseudo-second-order kinetics fitted the PO43̶ and NO3− adsorption, while Freundlich and Langmuir models best fitted the PO43̶ and NO3̶ adsorption, respectively. Furthermore, in the binary system, the uptake capacity of phosphate decreased by 14.4% while nitrate witnessed a reduction in its uptake capacity by 10.4 %. So ACWNS has a higher attraction towards both ions and this could be attributed to the existence of a variety of active areas on ACWNS that exhibit a degree of specificity for the individual anions. Results obtained from real water samples analysis confirmed ACWNS as highly efficient to be utilized for practical remediation processes.

scholarly journals Distinct Contributions of Different Domains within the HIV-1 Gag Polyprotein to Specific and Nonspecific Interactions with RNA

Viruses ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 394 ◽  
Author(s):  
Tomas Kroupa ◽  
Siddhartha A. K. Datta ◽  
Alan Rein
Keyword(s):  
Salt Concentration ◽  
Electrostatic Interactions ◽  
Rna Binding ◽  
High Specificity ◽  
Viral Rna ◽  
Gag Protein ◽  
Gag Polyprotein ◽  
The Individual ◽  
Hiv 1

Viral genomic RNA is packaged into virions with high specificity and selectivity. However, in vitro the Gag specificity towards viral RNA is obscured when measured in buffers containing physiological salt. Interestingly, when the binding is challenged by increased salt concentration, the addition of competing RNAs, or introducing mutations to Gag protein, the specificity towards viral RNA becomes detectable. The objective of this work was to examine the contributions of the individual HIV-1 Gag polyprotein domains to nonspecific and specific RNA binding and stability of the initial protein-RNA complexes. Using a panel of Gag proteins with mutations disabling different Gag-Gag or Gag-RNA interfaces, we investigated the distinct contributions of individual domains which distinguish the binding to viral and nonviral RNA by measuring the binding of the proteins to RNAs. We measured the binding affinity in near-physiological salt concentration, and then challenged the binding by increasing the ionic strength to suppress the electrostatic interactions and reveal the contribution of specific Gag–RNA and Gag–Gag interactions. Surprisingly, we observed that Gag dimerization and the highly basic region in the matrix domain contribute significantly to the specificity of viral RNA binding.

scholarly journals An Efficient Cluster Head Selection and Routing in Mobile WSN

2019 ◽  
Vol 13 (10) ◽  
pp. 56 ◽  
Author(s):  
Manikanthan S.V ◽  
Padmapriya T
Keyword(s):  
Network Formation ◽  
Cluster Head ◽  
Data Communication ◽  
Path Selection ◽  
Sensor Nodes ◽  
Destination Node ◽  
Cluster Head Selection ◽  
Multi Stage ◽  
Large Numbers ◽  
The Individual

Wireless Sensor Networks (WSN) includes numerous sensor nodes that are connected to each other through the use of wireless short distance links. The transfer of data between the individual nodes is found to be energy-constrained and the energy-efficient protocol in WSNs is a huge requirement. In addition, the deployment of large numbers of sensor nodes increases the size of the network, which in turn increases the energy consumption rate. An efficient protocol is developed in this research that includes grid-based mobile communication network formation, efficient path selection through cluster head selection and data communication. In addition, multi-stage authentication is implemented to provide security from source node to destination node for the transfer of data. Implementation is performed via NS2-based platform and the result obtained shows that the proposed system outperforms other existing techniques in terms of packet delivery and use of energy through network lifetime.

Advances in Theoretical Studies on the Design of Single Boron Atom Compounds

2018 ◽  
Vol 24 (29) ◽  
pp. 3466-3475 ◽  
Author(s):  
Martiniano Bello
Keyword(s):  
Molecular Recognition ◽  
Drug Design ◽  
Boron Atom ◽  
Force Fields ◽  
Covalent Binding ◽  
Binding Modes ◽  
In Silico Studies ◽  
Reversible Covalent ◽  
The Individual ◽  
Insight Into

Background: Single Boron Atom Compounds (SBACs) have been used for drug discovery in diseaseassociated proteins due to the empty p-orbital in the atomic structure of boron, which allows it to experience diverse binding modes during molecular recognition with a range of proteins. Objective: During the molecular recognition process with a protein target, SBACs can assume an anionic tetragonal arrangement or a neutral trigonal planar structure to produce four possible reversible covalent or non-covalent binding modes with a protein. However, the development of new SBACs has been hampered by the fact that most of the force fields present in many of the software packages used in drug design lack the various types of boron atom parameters. Methods: We review in silico studies in which a series of theory-based computational strategies have been used to overcome the lack of boron parameters in most of the force fields used in drug design. Results: The modeling studies discussed in this review have provided substantial insight into the molecular recognition of SBACs targeting different receptors, including the elucidation of some of the key interactions, which serve as a guide for the development of selective SBACs. Conclusion: Although the strategies employed in many of the studies presented here should serve in the development of selective SBACs, it is clear that the development of the precise force field parameters, which include not only the individual atom types but also the entire molecule, is still lacking, yet it is a necessary requirement for the design of new SBACS as well as for gaining insight into their molecular recognition.

Solid-State C-13 NMR Studies of Vulcanized Elastomers XVII. Effect of Carbon Black Grade on the Network Structure in Natural Rubber Vulcanizates

1997 ◽  
Vol 70 (4) ◽  
pp. 671-680 ◽  
Author(s):  
Makio Mori ◽  
Jack L. Koenig
Keyword(s):  
Solid State ◽  
Carbon Black ◽  
Natural Rubber ◽  
Network Formation ◽  
Physical Adsorption ◽  
Nmr Studies ◽  
Carbon Black Concentration ◽  
Effective Level ◽  
The Individual ◽  
Natural Rubber Vulcanizates

Abstract The vulcanization chemistry and network formation of carbon black filled natural rubber vulcanized with sulfur and TBBS were studied using solid-state C-13 NMR and equilibrium swelling measurements. A reduction in the sulfur rank of the A1 type sulfide and increased production of B1 type polysulfide are observed when the carbon black concentration increases in natural rubber. At the same loading level, the structural property or grade of carbon black does not affect qualitatively the type of sulfide formation. The efficiency of the intermolecular crosslinking over the whole range of sulfurizations is 45.7% for the unfilled vulcanizate. The extent of the chemical sulfurization reactions (NMR result) is constant with black incorporation, while the total network (swelling result) increases with increases in the black loading. The amount of physical entanglements, estimated from the comparison of the NMR and swelling results, is found to increase linearly with the carbon black concentration. The entanglements increase as a function of the 300% modulus, which suggests that the effective level of reinforcement depends on the nature of the individual carbon black. It is assumed that physical adsorption plays a major role in the polymer-filler interactions in the natural rubber/carbon black system.

scholarly journals DNA-Metallodrugs Interactions Signaled by Electrochemical Biosensors: An Overview

2007 ◽  
Vol 2007 ◽  
pp. 1-11 ◽  
Author(s):  
Mauro Ravera ◽  
Graziana Bagni ◽  
Marco Mascini ◽  
Domenico Osella
Keyword(s):  
Electrostatic Interactions ◽  
Electrochemical Biosensor ◽  
Covalent Binding ◽  
Electrochemical Biosensors ◽  
Dna Biosensors ◽  
New Techniques ◽  
Guanine Oxidation ◽  
Technological Advances ◽  
Semiquantitative Evaluation ◽  
Biological Environment

The interaction of drugs with DNA is an important aspect in pharmacology. In recent years, many important technological advances have been made to develop new techniques to monitor biorecognition and biointeraction on solid devices. The interaction between DNA and drugs can cause chemical and conformational modifications and, thus, variation of the electrochemical properties of nucleobases. The propensity of a given compound to interact with DNA is measured as a function of the decrease of guanine oxidation signal on a DNA electrochemical biosensor. Covalent binding at N7 of guanine, electrostatic interactions, and intercalation are the events that this kind of biosensor can detect. In this context, the interaction between a panel of antitumoral Pt-, Ru-, and Ti-based metallodrugs with DNA immobilized on screen-printed electrodes has been studied. The DNA biosensors are used for semiquantitative evaluation of the analogous interaction occurring in the biological environment.

scholarly journals Comparative Analysis of [Au(en)2]3+ and [Pt(en)2]2+ non Covalent Binding to Calf Thymus DNA

2000 ◽  
Vol 7 (5) ◽  
pp. 253-256 ◽  
Author(s):  
Giordana Marcon ◽  
Tim O'Connell ◽  
Pierluigi Orioli ◽  
Luigi Messori
Keyword(s):  
Comparative Analysis ◽  
Electrostatic Interactions ◽  
Covalent Binding ◽  
Minor Groove ◽  
Sodium Cyanide ◽  
Calf Thymus Dna ◽  
Minor Groove Binder ◽  
Calf Thymus ◽  
Dna Conformations ◽  
A Minor

Reactions of the complexes bisethylendiammine gold(III) and bisethylendiammine platinum(II) with calfthymus DNA were comparatively analysed. Both complexes bind DNA non-covalently most probably on the basis of electrostatic interactions. Binding of either complex at low ratios results into modest modifications of B-type DNA conformations, as detected by CD. Far larger CD alterations are observed at high ratios. The gold(III) chromophore is scarcely perturbed by DNA addition Binding of [Au(en)2]Cl3 to calf thymus DNA is reversed by sodium cyanide. By analogy with the case of [Pt(en)2]Cl2 it is suggested that Auen acts as a minor groove binder.

scholarly journals Multinozzle Multichannel Temperature Deposition System for Construction of a Blood Vessel

2017 ◽  
Vol 23 (1) ◽  
pp. 64-69 ◽  
Author(s):  
Huanbao Liu ◽  
Huixing Zhou ◽  
Haiming Lan ◽  
Fu Liu ◽  
Xuhan Wang
Keyword(s):  
Tissue Engineering ◽  
Blood Vessel ◽  
3D Model ◽  
Model Structure ◽  
3D Bioprinting ◽  
Porous Structures ◽  
Bioactive Materials ◽  
Organ Regeneration ◽  
Hierarchical Porous ◽  
Temperature Deposition

3D bioprinting is an emerging technology that drives us to construct the complicated tissues and organs consisting of various materials and cells, which has been in widespread use in tissue engineering and organ regeneration. However, the protection and accurate distribution of cells are the most urgent problems to achieve tissue and organ reconstruction. In this article, a multinozzle multichannel temperature deposition and manufacturing (MTDM) system is proposed to fabricate a blood vessel with heterogeneous materials and gradient hierarchical porous structures, which enables not only the reconstruction of a blood vessel with an accurate 3D model structure but also the capacity to distribute bioactive materials such as growth factors, nutrient substance, and so on. In addition, a coaxial focusing nozzle is proposed and designed to extrude the biomaterial and encapsulation material, which can protect the cell from damage. In the MTDM system, the tubular structure of a blood vessel was successfully fabricated with the different biomaterials, which proved that the MTDM system has a potential application prospect in tissue engineering and organ regeneration.

The Influence of Activators on the Vulcanization Process. II. The Influence of Zinc Oxide on the Structure of Vulcanizates

1959 ◽  
Vol 32 (3) ◽  
pp. 780-784 ◽  
Author(s):  
J. Beniska ◽  
B. Dogadkin
Keyword(s):  
Zinc Oxide ◽  
Stearic Acid ◽  
Zinc Sulfide ◽  
Network Formation ◽  
Marked Influence ◽  
Sh Groups ◽  
The Individual ◽  
Kinetics Of ◽  
Vulcanization Process ◽  
Kinetics Of Swelling

Abstract The influence of zinc oxide and stearic acid on the structures of vulcanizates was traced in stocks with mercaptobenzothiazole by means of the kinetics of swelling. It was found that zinc oxide in the presence of stearic acid has a marked influence on the rate and degree of crosslinked network formation in vulcanizates. In the formation of crosslinks (sulfur bridges) a number of reactions participate: the direct combination of rubber molecules with biradicals of sulfur, during which polysulfide bonds are mainly formed; the oxidation of rubber mercaptans (-SH groups), which is followed by the formation of mono-sulfide, disulfide and polysulfide links; and the decomposition of polysulfide links, which is followed by the formation of new crosslinks with a smaller number of sulfur atoms per crosslink. Zinc oxide has a varying influence on the individual reactions : the first two are activated by it, and the last one is retarded by it, because it does not react with the polysulfide sulfur to form zinc sulfide.

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