Literature

https://www.mdpi.com/journal/molecules/special_issues/gelatin

Sergio Calixto, Nina Ganzherli, Sergey Gulyaev and Susana Figueroa-Gerstenmaier

doi:10.3390/molecules23082064

Abstract: Because this issue journal is dedicated to Gelatin, here we present a few applications of gelatin in the field of optics. Optics is the science that studies the production, propagation, interaction and detection of light. Various materials sensitive to light (photosensitive) are used for detection of light, such as photomultipliers, CCDs, crystals, two dimensional (2D) materials and more. Among the 2D materials, the most popular for several centuries has been gelatin based photographic emulsion, which records spatial distributions of light. More recently (1970), films made of Gelatin with Dichromate (DCG) and dyes have been used. We describe some characteristics and applications of these two photosensitive materials. We also describe examples where gelatin is used as a Relative Humidity (RH) sensor and in the fabrication of optical elements based on gelatin. This article is intended for researchers outside the optics community. Keywords: gelatin; photosensitive materials; silver halide photographic emulsion; dichromated gelatin; selective tanning; short-wave UV radiation; photodestruction; diffraction efficiency; dyed gelatin; holographic structures; Weigert effect

Lukasz Radosinski, Karolina Labus, Piotr Zemojtel and Jakub W. Wojciechowski

doi:10.3390/molecules24183365

Abstract: To successfully design and optimize the application of hydrogel matrices one has to effectively combine computational design tools with experimental methods. In this context, one of the most promising techniques is molecular modeling, which requires however accurate molecular models representing the investigated material. Although this method has been successfully used over the years for predicting the properties of polymers, its application to biopolymers, including gelatin, is limited. In this paper we provide a method for creating an atomistic representation of gelatin based on the modified FASTA codes of natural collagen. We show that the model created in this manner reproduces known experimental values of gelatin properties like density, glass-rubber transition temperature, WAXS profile and isobaric thermal expansion coefficient. We also present that molecular dynamics using the INTERFACE force field provides enough accuracy to track changes of density, fractional free volume and Hansen solubility coefficient over a narrow temperature regime (273–318 K) with 1 K accuracy. Thus we depict that using molecular dynamics one can predict properties of gelatin biopolymer as an efficient matrix for immobilization of various bioactive compounds, including enzymes.

Keywords: biopolymers; gelatin; hydrogel; molecular dynamics; functional polymeric matrices

Robert D. Groot, Arjen Bot and Wim G. M. Agterof

J. Chem. Phys., Vol. 104, No. 22, p. 9202, 8 June 1996

The elasticity of gelatin gels at large deformation has been measured for various experimental conditions. The general pattern is that stress increases with strain in a nonlinear way up to the point where the gel fails. To interpret this nonlinear stress increase, we studied a number of molecular models by Monte Carlo simulation and by mean-field methods. The effect of finite polymer length is studied via the FENE model ~finite extensible nonlinear polymer connections! and via the exact statistics of Kramers’ model ~chains of freely rotating stiff rods! for a small number of elements per chain. To investigate the effect of fractal connections, the end-point distribution that comes forward from scaling theory has been generalized to arbitrary fractal dimension. Finally we studied a heterogeneous network model: connections formed by rods and coils. We also discuss the consequence of microphase separation. Combining experiment and theory we conclude the following: ~i! The elastically active network connections in gelatin are most certainly not Gaussian. ~ii! Strain hardening in gelatin can be attributed to either: ~a! finite polymer length ~the chain length between connection points should be some 2.5 times the persistence length!, or ~b! a fractal structure of the polymer strands ~the fractal dimension should be roughly d f 51.3–1.5!, or ~c! the presence of both stiff rods and flexible coils ~the length of the rods should be 1.4–4.4 times the radius of gyration of the coils!. ~iii! Models b and c describe the experimental data significantly better than model a. From a single parameter ~the fractal dimension! the fractal model correctly describes ~1! the nonlinearity of the stress–strain curve, ~2! the scaling of Young’s modulus with polymer concentration, ~3! the scaling of neutron scattering intensity with wave number, and ~4! it predicts the scaling exponent of the linear dynamic modulus with frequency in the glassy transition zone ~no experimental data available!. The experimental parameters found for the rod1coils model suggest a Rouse diffusion controlled growth mechanism for the rods. Although the theory presented here is applied to gelatin, its formulation is quite general, and its implications are also relevant for other strain hardening polymer gels.

E H Schacht doi:10.1088/1742-6596/3/1/004

Masutani EM, Kinoshita CK, Tanaka TT, Ellison AK, Yoza BA. Increasing Thermal Stability of Gelatin by UV-Induced Cross-Linking with Glucose. Int J Biomater. 2014;2014:979636. doi: 10.1155/2014/979636. Epub 2014 May 21. PMID: 24963297; PMCID: PMC4055452.

DOI: 10.1155/2014/979636

carbon/research/IJBM2014-979636.pdf

Wonseok Lee, Sanggyu Chong, Jihan Kim Subjects: Computational Engineering, Finance, and Science (cs.CE); Materials Science (cond-mat.mtrl-sci)

https://arxiv.org/abs/2401.06152

In this study, a versatile methodology for initiating polymerization from monomers in highly cross-linked materials is investigated. As polymerization progresses, force-field parameters undergo continuous modification due to the formation of new chemical bonds. This dynamic process not only impacts the atoms directly involved in bonding, but also influences the neighboring atomic environment. Monitoring these complex changes in highly cross-linked structures poses a challenge. To address this issue, we introduce a graph-network-based algorithm that offers both rapid and accurate predictions. The algorithm merges polymer construction protocols with LAMMPS, a large-scale molecular dynamics simulation software. The adaptability of this code has been demonstrated by its successful application to various amorphous polymers, including porous polymer networks (PPNs), and epoxy-resins, while the algorithm has been employed for additional tasks, such as implementing pore-piercing deformations and calculating material properties.

Mounika Gosika, Angel J. Moreno

https://arxiv.org/abs/2310.20553

Ivan Kryven

https://doi.org/10.1038/s41467-018-08009-9

Percolation in complex networks is a process that mimics network degradation and a tool that reveals peculiarities of the network structure. During the course of percolation, the emergent properties of networks undergo non-trivial transformations, which include a phase transition in the connectivity, and in some special cases, multiple phase transitions. Such global transformations are caused by only subtle changes in the degree distribution, which locally describe the network. Here we establish a generic analytic theory that describes how structure and sizes of all connected components in the network are affected by simple and colour-dependent bond percolations. This theory predicts locations of the phase transitions, existence of wide critical regimes that do not vanish in the thermodynamic limit, and a phenomenon of colour switching in small components. These results may be used to design percolation-like processes, optimise network response to percolation, and detect subtle signals preceding network collapse.

Samira Chaibi & Djafer Benachour & Meriem Merbah & M. Esperanza Cagiao & Francisco J. Baltá Calleja 10.1007/s00396-015-3660-2

Abstract The crosslinking of gelatin using crosslinking agents based on condensation of the aldehyde groups and ε- amine groups present in lysine and hydroxylysine rests is a very attractive method reported recently. The present work deals with different films prepared from commercial gelatin of type B and animal origin, aiming at an improvement of physical properties. These films were modified by two plasti- cizing agents (glycerol, GLY, and poly (vinyl alcohol), PVA) and/or crosslinked by glutaraldehyde (GTA). The number of ε-amino groups present in the gelatin chains, before and after modification, was determined by the method of protein dos- age using 2,4,6-trinitro benzene sulfonic acid (TNBS). The addition of the plasticizing and/or crosslinking agents induced a decrease in the number of ε-amino-groups due to the fact that these groups are involved in the physical and/or chemical crosslinking reactions occurring among the different compo- nents. The variation of the crosslinking ratio was studied as a function of formulation type, crosslinking nature and GTA concentration. The use of microhardness (H) in this study emphasizes the effect of the crosslinking on the improvement of the micromechanical properties. The study of differential scanning calorimetry reveals that crosslinking induces a dras- tic decrease of crystallinity in the samples.

J.K. Jørgensen, Aage Stori, Keith Redford, Espen Ommundsen doi:10.1016/j.polymer.2005.10.084

Abstract Metallocene synthesised HDPE with MwZ82,000 and MnZ40,000 was modified with small amounts of 1,3-benzenedisulfonyl azide by reactive extrusion at 200 8C with the purpose to form long-chain branches. At the processing temperature the two azide groups decompose to nitrenes that work as cross-linkers for PE. Cross-linking occurs primarily by insertion of singlet nitrenes into CH bonds. Size exclusion chromatography revealed that the modification resulted in the formation of a long-chain branched (LCB) high molecular weight fraction. The LCB was detectable with SEC for concentrations above 100 ppm corresponding to approximately 0.03–0.04 branch points pr 104 carbon. No signs of the formation of low molecular species due to chain scission were observed. Dynamical mechanical analysis and shear creep test showed sign of long chain branching at concentrations down to the same limit as SEC (100 ppm). These signs were thermorheological complexity, increased zero shear viscosity, increased shear thinning and increased recovery compliance. The cross-linking efficiency of 1,3-BDSA were estimated to 40–60% from comparison of SEC data with random cross-linking theory and traditional SEC-LCB analyses.

Keywords: Cross-linking; Long-chain branching; Sulfonyl azides

Silke Keller, Tomke Bakker, Benjamin Kimmel, Lisa Rebers, Tobias Götz, Günter E. M. Tovar, Petra J. Kluger, Alexander Southan1 DOI: 10.1002/jbm.a.37008

Abstract Gelatin is one of the most prominent biopolymers in biomedical material research and development. It is frequently used in hybrid hydrogels, which combine the advantageous properties of bio-based and synthetic polymers. To prevent the biolog- ical component from leaching out of the hydrogel, the biomolecules can be equipped with azides. Those groups can be used to immobilize gelatin covalently in hydrogels by the highly selective and specific azide–alkyne cycloaddition. In this contribution, we functionalized gelatin with azides at its lysine residues by diazo transfer, which offers the great advantage of only minimal side-chain extension. Approximately 84– 90% of the amino groups are modified as shown by 1H-NMR spectroscopy, 2,4,6- trinitrobenzenesulfonic acid assay as well as Fourier-transform infrared spectroscopy, rheology, and the determination of the isoelectric point. Furthermore, the azido-func- tional gelatin is incorporated into hydrogels based on poly(ethylene glycol) diacrylate (PEG-DA) at different concentrations (0.6, 3.0, and 5.5%). All hydrogels were classified as noncyctotoxic with significantly enhanced cell adhesion of human fibroblasts on their surfaces compared to pure PEG-DA hydrogels. Thus, the new gelatin derivative is found to be a very promising building block for tailoring the bioactivity of materials.

KEYWORDS biocompatibility, biopolymers, functional materials, hydrogels, tissue engineering