A Mini-Review for an Adsorption of Polycyclic Aromatic Hydrocarbons (PAHs) by Physical Gel

On 4 December in 2002, the mainstream source of exposure to Polycyclic Aromatic Hydrocarbons (PAHs) was defined by the Scientific Committee as food and inhaled air. Several Polycyclic Aromatic Hydrocarbons (PAHs) such as benzo[a]pyrene, chrysene, and dibenzo(a,h)anthracene in food caused the risk of human health. These are produced by the cooking processes, including combustion processes and pyrolysis sources. Certain food preparation methods like grilling, roasting, and smoking are accumulated PAHs in the sink pipes. As PAHs are toxic and carcinogenic, it raises health and environmental problems. What is the method for preventing PAHs exist in wastewater? This review article introduces a functional material, gelatin physical gels, to trap and remove the PAHs. The physical gel changes from colorless to pale yellow during the adsorption of PAHs in household wastewater. The concentration of PAHs is determined by GC-MS analysis, which decreases the potential risk of human exposure in an environment with PAHs.

Design of a Waterborne Polyurethane–Urea Ink for Direct Ink Writing 3D Printing

In this work, polycaprolactone–polyethylene glycol (PCL–PEG) based waterborne polyurethane–urea (WBPUU) inks have been developed for an extrusion-based 3D printing technology. The WBPUU, synthesized from an optimized ratio of hydrophobic polycaprolactone diol and hydrophilic polyethylene glycol (0.2:0.8) in the soft segment, is able to form a physical gel at low solid contents. WBPUU inks with different solid contents have been synthesized. The rheology of the prepared systems was studied and the WBPUUs were subsequently used in the printing of different pieces to demonstrate the relationship between their rheological properties and their printing viability, establishing an optimal window of compositions for the developed WBPUU based inks. The results showed that the increase in solid content results in more structured inks, presenting a higher storage modulus as well as lower tan δ values, allowing for the improvement of the ink’s shape fidelity. However, an increase in solid content also leads to an increase in the yield point and viscosity, leading to printability limitations. From among all printable systems, the WBPUU with a solid content of 32 wt% is proposed to be the more suitable ink for a successful printing performance, presenting both adequate printability and good shape fidelity, which leads to the realization of a recognizable and accurate 3D construct and an understanding of its relationship with rheological parameters.

ABA Type Amphiphiles with Poly(2-Benzhydryl-2-Oxazine) Moieties: Synthesis, Characterization and Inverse Thermogelation

<div>Thermoresponsive polymers are frequently discussed for various applications. Here, we introduce a novel amphiphilic triblock copolymer, which undergoes inverse thermogelation, i.e. is forms a physical gel upon cooling. The polymers comprises poly(2-benzhydryl-2-oxazine) as the hydrophobic building block, a polymer which has not been reported to date. The physical gels are surprisingly strong with a storage modulus of 22 kPa at 25 wt.% in water. In addition, relatively high yield and flow points were determined by rheology.</div>

ABA Type Amphiphiles with Poly(2-Benzhydryl-2-Oxazine) Moieties: Synthesis, Characterization and Inverse Thermogelation

<div>Thermoresponsive polymers are frequently discussed for various applications. Here, we introduce a novel amphiphilic triblock copolymer, which undergoes inverse thermogelation, i.e. is forms a physical gel upon cooling. The polymers comprises poly(2-benzhydryl-2-oxazine) as the hydrophobic building block, a polymer which has not been reported to date. The physical gels are surprisingly strong with a storage modulus of 22 kPa at 25 wt.% in water. In addition, relatively high yield and flow points were determined by rheology.</div>

Influence of Propylene Glycol Concentrations in Mangostin Pericarp Extract Gels Formulation: Gels Physical Characteristics, Antibacterial Activity Against Staphylococcus aureus, and Functional Antioxidant Activity Based on Radical 2,2-diphenyl-1-picrylhydrazyl Scavenging Activity

Mangostin (Garcinia mangostana L.) fruit pericarp (GMP) extract has been shown to have antimicrobial and antioxidant activities. This study aimed to formulate and evaluate gel formulations of GMP extract using sodium carboxymethylcellulose as a gelling agent and propylene glycol (PG) in varying concentrations (i.e. 0-40%). GMP extract was evaluated for total mangostin content and antioxidant activity based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method. Physical gel characteristics were also examined. All gels had similar pH and spreadability, however, gel with 40% PG produced significantly lower viscosity. Antibacterial activities against S.aureus were shown to be the same among GMP extract gels. The antioxidant activity of all GMP extract gels could be confirmed based on the radical DPPH scavenging method. PG content of 40% significantly reduced the increase of GMP extract gel viscosity after being stored for four weeks at room temperature. Additionally, the lowest syneresis was also shown for GMP extract gel with 40% PG content.

The Effect of the HLB Value of Sucrose Ester on Physiochemical Properties of Bigel Systems

The current research explored the effect of different sucrose esters (SEs), with different hydrophilic–lipophilic balance (HLB) values, on bigel structure and properties. Bigels consisting of a water phase with glycerol and gelatin and an oil phase with glycerol mono-stearate, lecithin, and SEs with different HLB values were prepared. Rheological and thermal analyses revealed similar gelation-melting transitions governed by glycerol-monostearate crystallization (at ≈55 °C) for all bigel samples. The bigel matrix of the H1 and H2 samples (bigels consisting of SEs with HLBs of 1 and 2, respectively) demonstrated physical gel rheological characteristics of higher elastic and solid-like behavior compared with the H6 sample (bigel consisting SE with HLB 6). A similar trend was observed in the mechanical analysis with respect to hardness, firmness, and spreadability values, which were in the order of H1 > H2 > H6. This behavior was attributed to droplet size observed in the microscopy analysis, revealing significantly smaller droplets in the H1 and H2 samples compared with the H6 sample. These differences in droplet size were attributed to the diffusion kinetics of the low-molecular-weight surfactants. More specifically, the ability of mono-esterified SEs to diffuse faster than fully esterified SEs due to lower molar mass leads to a higher SE content at the oil-in-water (O/W) interface as opposed to the bulk oil phase. The results demonstrate the importance of the interface content in O/W bigel systems, providing an effective way to alter and control the bigel bulk properties.

Synthesis and Investigation of Thermo-Induced Gelation of Partially Cross-Linked Poly-2-isopropyl-2-oxazoline in Aqueous Media

Water-soluble, partially cross-linked poly-2-isopropyl-2-oxazoline combining the properties of chemical and physical gels was synthesized by a two-step procedure. Thermally induced sol-gel transition in its aqueous solution was studied by rheology, light scattering, and turbidimetry. It was demonstrated that the synthesized product is bimodal; it consists of linear and cross-linked components. The cross-linked components are responsible for the gelation, while the linear ones abate the viscosity growth. Heating the solution above the phase transition temperature leads to the self-assembly of the particles into a physical gel. The combination of chemical and physical cross-linking was found to be a prospective route for thermosensitive gel development.

Bioinspired Thermosensitive Hydrogel as a Vitreous Substitute: Synthesis, Properties, and Progress of Animal Studies

In many vitreal diseases, the surgeon removes the natural vitreous and replaces it with silicone oils, gases, or balanced salt solutions to fill the eyeball and hold the retina in position. However, these materials are often associated with complications and have properties that differ from natural vitreous. Herein, we report an extension of our previous work on the synthesis of a biomimetic hydrogel that is composed of thiolated gellan as an analogue of type II collagen and poly(methacrylamide-co-methacrylate-co-bis(methacryloyl)cystamine), a polyelectrolyte, as an analogue of hyaluronic acid. This thermosensitive hydrogel can be injected into the eye as a viscous solution at 45 °C. It then forms a physical gel in situ when it reaches body temperature, and later forms disulfide covalent crosslinks. In this article, we evaluated two different formulations of the biomimetic hydrogels for their physical, mechanical, and optical properties, and we determined their biocompatibility with several cell lines. Finally, we report on the progress of the four-month preclinical evaluation of our bio-inspired vitreous substitute in comparison to silicone oil or a balanced salt solution. We assessed the eyes with a slit-lamp examination, intraocular pressure measurements, electroretinography, and optical coherence tomography. Preliminary results are very encouraging for the continuing evaluation of our bio-inspired hydrogel in clinical trials.