Physics advocates research on unifying chemical bonds and recognized parallels on a different (and non-reductive) level, as per the concept of the Great Unification of Forces in Nature. From this perspective, a Physicochemical Grand Unification of Forces would be a worthy project for humankind in order to increase our undertanding of existence and to improve our lives. This entry collection aims to present an account of chemical bonds and interactions in nano- to maco-environments.

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Topic Review
Interplay between Polyphenols and Lysyl Oxidase Enzymes
Collagen, the most abundant structural protein found in mammals, plays a vital role as a constituent of the extracellular matrix (ECM) that surrounds cells. Collagen fibrils are strengthened through the formation of covalent cross-links, which involve complex enzymatic and non-enzymatic reactions. Lysyl oxidase (LOX) is responsible for catalyzing the oxidative deamination of lysine and hydroxylysine residues, resulting in the production of aldehydes, allysine and hydroxyallysine. These intermediates undergo spontaneous condensation reactions, leading to the formation of immature cross-links, which are the initial step in the development of mature covalent cross-links. Additionally, non-enzymatic glycation contributes to the formation of abnormal cross-linking in collagen fibrils. During glycation, specific lysine and arginine residues in collagen are modified by reducing sugars, leading to the creation of Advanced Glycation End-products (AGEs). These AGEs have been associated with changes in the mechanical properties of collagen fibers.
  • 254
  • 13 Jul 2023
Topic Review
Hydrogels Based on Supramolecular Strategies
Supramolecular structures are of great interest due to their applicability in various scientific and industrial fields. The sensible definition of supramolecular molecules is being set by investigators who, because of the different sensitivities of their methods and observational timescales, may have different views on as to what constitutes these supramolecular structures. The supramolecular interaction between some materials and guest molecules has endowed gels with the capacity for reversible gel−sol transformation. A plausible example has to do with self-healing, which is one of the most intriguing characteristics of biological or artificial systems, such as the particular and specific applications described below, due to its intrinsic importance. Thermodynamic stability plays an important role, for example, in the preparation of ophthalmic hydrogels and metallo-supramolecular hydrogels.
  • 390
  • 19 Jun 2023
Topic Review
Silanes, as organic-inorganic hybrid modifiers of hyperbranched polymer (HBP), are of great interest as they resulted in a tremendous improvement in HBP properties like increasing thermal, mechanical and electrical properties compared to that of organic-only moieties. The basic components of silanes are monomeric silicon (Si) compounds with four substituent groups attached to the Si atom, which can be of any combination of reactive or non-reactive inorganic or organic groups, which are the fundamental building blocks of silanes.
  • 181
  • 14 Jun 2023
Topic Review
Applications of Polyvinyl Alcohol-Chitosan Hydrogel
Tissue engineering and regenerative medicine (TERM) holds great promise for addressing the growing need for innovative therapies to treat disease conditions. To achieve this, TERM relies on various strategies and techniques. The most prominent strategy is the development of a scaffold. Polyvinyl alcohol-chitosan (PVA-CS) scaffold emerged as a promising material in this field due to its biocompatibility, versatility, and ability to support cell growth and tissue regeneration. 
  • 192
  • 07 Jun 2023
Topic Review
Metal Hydrides and Graphene Supports
Energy production, distribution, and storage remain paramount to a variety of applications that reflect on our daily lives, from renewable energy systems, to electric vehicles and consumer electronics. Hydrogen is the sole element promising high energy, emission-free, and sustainable energy, and metal hydrides in particular have been investigated as promising materials for this purpose. While offering the highest gravimetric and volumetric hydrogen storage capacity of all known materials, metal hydrides are plagued by some serious deficiencies, such as poor kinetics, high activation energies that lead to high operating temperatures, poor recyclability, and/or stability, while environmental considerations related to the treatment of end-of-life fuel disposal are also of concern. Graphene is a 2D material with very appealing properties, highlighting its potential use as support for various reactive species, including metals and metal hydrides. By embedding hydride species into graphene supports, valuable nanocomposites can be obtained with direct use for energy storage applications.
  • 215
  • 01 Jun 2023
Topic Review
Advantages and Disadvantages of Covalent Inhibitors
The formation of covalent bonds that target proteins can offer drugs diverse advantages in terms of target selectivity, drug resistance, and administration concentration. The most important factor for covalent inhibitors is the electrophile (warhead), which dictates selectivity, reactivity, and the type of protein binding (i.e., reversible or irreversible) and can be modified/optimized through rational designs. Furthermore, covalent inhibitors are becoming more and more common in proteolysis, targeting chimeras (PROTACs) for degrading proteins, including those that are currently considered to be ‘undruggable’.
  • 607
  • 10 May 2023
Topic Review
Processes for Obtaining Syngas and Hydrogen
The growing demand for high-quality chemical products has already stimulated an increased interest in the conversion of hydrocarbon gases (natural gas, methane, biogas) into motor fuels and high value-added chemical products, as well as into hydrogen, which is increasingly in demand on the market. The conversion of natural gas into hydrogen and syngas is still the most complex and costly stage of modern gas chemical processes, the low efficiency of which hinders the development of modern gas chemistry. 
  • 291
  • 14 Apr 2023
Topic Review
Chemically Activated Glass-Ionomer Cements as Bioactive Materials
Glass-ionomer cement (GIC) is a long-established restorative dental material with several clinical applications that have remained relevant because of the chemical adhesive bond it forms at the tooth-restoration interface and its fluoride-releasing and recharging properties. It was invented by Wilson and Kent in 1969 and successfully introduced into clinical practice in 1972. Chemically activated GICs, commonly referred to as conventional GICs, typically consist of ion-leachable glasses based on calcium or strontium alumino-fluorosilicate and weak polymeric water-soluble acids of polyacrylic acid (PAA) homopolymer, or acrylic acid, maleic/itaconic acid copolymer. They set by an acid-base reaction, and the setting reaction is initiated by mixing glass powder and polymeric acids. 
  • 440
  • 30 Mar 2023
Topic Review
Aminoacid Surfactants
Aminoacid surfactants are a type of surfactant that is composed of both an amino acid and a hydrophobic tail. They have both hydrophilic and hydrophobic properties, which allows them to lower the surface tension between two immiscible phases, such as oil and water. Aminoacid surfactants are becoming increasingly popular in personal care and cosmetic products due to their mildness and biocompatibility. They are often used as alternatives to traditional surfactants, which can be harsh and irritating to the skin and eyes. Here are several types of amino acid surfactants, each with its own unique properties and applications. Alkyl-L-glutamate, alkyl-L-amino acids, alkyl-D-amino acids, alkyl-amino acids, and dipeptide surfactants are just a few examples of the different types of amino acid surfactants available. With their biodegradability, low toxicity, and excellent foaming and emulsifying properties, amino acid surfactants are a valuable addition to the surfactant industry.
  • 1067
  • 24 Mar 2023
Topic Review
Insights into Si-Si and Si-H Bond
During the last decades, the search for new methodologies for the synthesis of organosilicon compounds have increased due to the multiple applications in industry, in academy, among other areas. Silicon-hydrogen and silicon-silicon bond activation by d-block metals still represent the most important pathways for obtaining molecular entities that contain, witihin their structures, silane motifs. Although the chemistry of Si-H bond activation is under continue development, Si-Si bonds are poorly characterized and less used and thus, disilanes represent good starting precursors because of their stability towards ambient conditions. The present entry will focus on the physicochemical properties of Si-H and Si-Si bonds, some trends and finally highlighting their impact on the synthesis of metal complexes.
  • 1036
  • 15 Feb 2023
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