Proteins in Cosmetics
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
Proteins having large molecular masses show water- and fat-binding capacity, airtrapping activity, gelling, thickening, and emulsifying properties. Gelation phenomena are often observed in protein solutions and dispersions; they are mainly due to the attraction-repulsion forces between charged groups in the protein, which leads to the formation of a three-dimensional network where water molecules are entrapped. This effect is generally amplified when an excess of ionized carboxylic groups is present, leading to prevailing repulsive forces with subsequent unfolding of polypeptide chains . This general behavior is supported by comparisons of the properties of native proteins with deamidated and succinylated derivatives, where additional carboxylic groups are introduced in the protein molecules. Protein gels are characterized by a relatively high viscosity, plasticity, and elasticity; they are used to provide a structural matrix for holding water, flavors, sugars, and other ingredients in food applications. Gelation has not been used so far in cosmetic systems, owing to the relatively high content of protein required and because the systems obtained are generally opaque, but development of enhanced modified protein will probably make this effect of some importance in cosmetic preparations.
Injectable Scaffolds for Bone Tissue Repair and Augmentation
Naznin Sultana, Sanchita Bandyopadhyay-Ghosh, Chin Fhong Soon in Tissue Engineering Strategies for Organ Regeneration, 2020
The intermediate period between mixing and gelation (working time) is an important parameter to characterizing settability. Working time is usually calculated from the cure profile (rheological) obtained under constant strain conditions (Page et al. 2013). Gelation time can be evaluated by ‘inverted tube test’, as proposed by Gupta and co-workers (Gupta et al. 2006). In this test, if a tube is tilted and the injectable solution flows, it is defined as a sol phase, while it is considered to be in gel phase if the solution cannot flow. The time at which the gel does not flow is defined as the gelation time. International standard ISO 9917 is used to determine the setting times of the bone cements. A Gilmore needle method is usually used to find out the setting time. The cement specimen is considered to be set when a tip needle of 1 mm diameter, loaded with 400-g mass does not make perceptible circular indentation on the surface of the cement (Li et al. 2008).
Marine Biopolymers
Se-Kwon Kim in Marine Biochemistry, 2023
In the fast gelation with Ca2+, as illustrated in Figure 3.3, when the sodium alginate is dropped into the Ca2+ solution (CaCl2), the process of gelation happens immediately in the surface of the drop. In the meantime, when the cations of Ca2+ penetrate into the drop, the gelation will pull the alginate molecules from the center of the drop to the surface. Because of that, the content of alginate near the surface of the drop (becoming the gel bead) is higher in the center and we obtain the heterogenous gel. Figure 3.3 shows that the center of the gel bead has the very low alginate content and becomes the hole of solution. This feature is convenient for immobilization of cells since the cells will accumulate with high density near the surface, the mass transfer into and out of the gel is faster, and the effectiveness of the biocatalyst is better. The mechanism of fast gelation is proved in Figure 3.4. In the cross-section of a calcium alginate gel bead after the immobilization of yeast cells, Figure 3.4 clearly shows the hollow area (zero zone) in the center of the gel bead with only aqueous solution, with the gel with cells concentrated near the surface of the gel bead.
Biofilm inhibition and antifouling evaluation of sol-gel coated silicone implants with prolonged release of eugenol against Pseudomonas aeruginosa
Published in Biofouling, 2021
Prasanth Rathinam, Bhasker Mohan Murari, Pragasam Viswanathan
Room temperature-processed acid-base catalyzed sol–gels have been used for various biomedical applications due to their widely accepted bioresorbable and biocompatible properties, tailorable composition and microstructure, excellent prolonged release properties, the ease of introducing multiple functional groups or elements, and the possibility of depositing them on any substrata by using inexpensive and straightforward techniques (Brinker and Scherer 2013). The sol–gel process involves the transition of a solution system from a liquid ‘sol’ (mostly colloidal) into a solid ‘gel’ phase through gelation, condensation and drying processes (Dehghanghadikolaei et al. 2018). Large quantities of biological molecules can be added into the porous solution system and uniformly distributed in the concrete matrix. Thus, sol–gels are prepared as thin films, coatings and hydrogels for fire-retardant, anti-static, water/oil repellent, insect-repellent, antimicrobial and catalytic applications, as well as for the encapsulation of enzymes, proteins, growth factors and antimicrobial agents (Brinker and Scherer 2013).
Incorporation of rosuvastatin-loaded chitosan/chondroitin sulfate nanoparticles into a thermosensitive hydrogel for bone tissue engineering: preparation, characterization, and cellular behavior
Published in Pharmaceutical Development and Technology, 2019
Mahboubeh Rezazadeh, Maryam Parandeh, Vajihe Akbari, Zahra Ebrahimi, Azade Taheri
Between different PF127/HA hydrogel systems, P20/H2 existed in a sol at room temperature which was converted to a semisolid gel when the temperature was increased to 35 °C. The in vitro morphology of the P20/H2 hydrogels before and after incorporation of the CTS/CS nanoparticles is shown in Figure 6. Gel formation was also traced through the viscosity of the systems, which significantly increased during the gelation process. Figure 7 illustrates the temperature-dependent gelation of PF127 and the CTS/CS-embedded P20/H2 hydrogel. PF127 showed rapid increase (in a few seconds) in viscosity at 35 °C; however, the nanoparticles loaded P20/H2 system began to gel process at 27 °C, and the viscosity increased to 70 Pa.s until 35 °C (within 120 s). The gelation behavior of P20/H2 without nanoparticles was similar to Figure 7(b) with slight decrease in gelation time (data not shown). In particular, the presence of HA and HPMC did not hamper the PF127 gelation process; rather, it led to increase in viscosity of the system.
Unification of medicines and excipients: The roles of natural excipients for promoting drug delivery
Published in Expert Opinion on Drug Delivery, 2023
Minfang Feng, Xingxing Dai, Cuiting Yang, Yingying Zhang, Yuting Tian, Qingsong Qu, Mengke Sheng, Zhixun Li, Xinhui Peng, Shuai Cen, Xinyuan Shi
The gel is a three-dimensional network structure formed by cross-linking polymers or colloidal particles with a linear structure through chemical bonds between molecules (including intra-molecular and extra-molecular interactions). The types of chemical bonds are based on their structures and properties. The occurrence of gelation can be affected by temperature, solution pH, ions, etc. So, the gelation of solutes can be triggered by changing temperature or other influencing factors. For the gelation of polysaccharide molecules in water, the polysaccharides are associated with each other through chemical bonds. And they stabilize the water molecules around them by hydrogen bonds between water molecules and polysaccharides and lead to hydrogen bonds between water molecules and water molecules, which results in gelation [225–227]. Polysaccharides in herbal medicine frequently crosslink with polymer by the effect of crosslinkers like Psyllium polysaccharide, Bletilla striata polysaccharide, Tremella polysaccharide, etc. The forming mechanism of Psyllium polysaccharide-based hydrogel is shown in Figure 6. Firstly, trigger the propagation of Psyllium polysaccharide, acrylamide(AAm), and methacrylamide(MAAm). Then, Psyllium polysaccharide, AAm/MAAm polymer, was generated. Last, a three-dimensional network was formed after adding a crosslinker(N, N’-methylenebisacrtlamide) crosslinked the AAm/MAAm polymer and Psyllium polysaccharide.
Related Knowledge Centers
- Macromolecule
- Polymer
- Polymer Chemistry
- Gel
- Branching
- Cross-Link
- Thickening Agent
- Flory–Stockmayer Theory
- Carothers Equation
- Mechanics of Gelation