Polyacrylamide Hydrogel Enriched with Amber for In Vitro Plant Rooting

Novel biochar-filled hydrogel composites: Assessment of multifunctionality and potential in environmental applications

Hydrogels (HGs) are hydrophilic 3D-cross-linked polymers applied, inter alia, to improve soil resistance to drought. Their combination with biochar (BC), a product of biomass pyrolysis, can result in obtaining specific composites characterized by the advantages of both initial materials. The BC introduction into HG can double its swelling degree and increase their sorption capacity by more than threefold compared to the pure HG. Furthermore, the composites are able to increase plants biomass (up to 160%), even under heavy metal contamination, and are characterized by lower nutrient release rate (up to 25%) in comparison to the pure hydrogels. This review explores the properties of biochar-filled hydrogel composites, including swelling degrees and ability to absorb heavy metals and other toxic compounds. Additionally, it discusses their agricultural applications as soil conditioners and slow-release fertilizers, covering their effects on water and nutrient retention in the soil, soil microbial activity, as well as plant performance under contamination and drought stress. Finally, the cost-economic assessment and future prospects of these novel materials were proposed. The BC-filled HGs were considered as highly promising soil amendments, but their application potential depended entirely on the development of new production technologies and the investigation of interactions occurring between the composites and the selected soil components.

Polyacrylamide Hydrogel Containing Starch and Sugarcane Bagasse Ash: Synthesis, Characterisation, and Application in Cement Pastes and Mortars

Internal curing is a process based on the addition of materials that function as water reservoirs in cementitious media. Superabsorbent hydrogels are an alternative that can be used as an internal curing agent, as they have the ability to absorb and release water in a controlled manner. In the present work, superabsorbent hydrogels based on crosslinked polyacrylamide in the presence of starch and sugarcane bagasse ash (SCBA) were developed and applied to mortars as an internal curing agent. The synthesized hydrogels were evaluated by SEM, FTIR, and swelling analysis. Cement pastes and mortars were produced using different amounts of hydrogel (0.03%, 0.06%, and 0.1% by weight). An analysis of the cement pastes and mortars revealed that hydrogel contributes to hydration, thus improving the quality of the product. Furthermore, the addition of 0.03% hydrogel by weight increased the mechanical resistance of the mortars in up to 26.8% at 28 days of curing as compared with reference (without hydrogel). To the best of our knowledge, this is the first study to use a hydrogel based on polyacrylamide crosslinked with starch and SCBA as a curing agent for mortars and cement pastes. This approach is environmentally friendly, because it uses a natural product (starch) and a byproduct from the sugarcane industry (SCBA).

Synthesis, characterization and biocompatibility of hybrid hydrogels based on alginate, κ-carrageenan, and chitosan filled with montmorillonite clay

New hybrid hydrogel composites based on a mixture of natural polysaccharides (sodium alginate, κ-carrageenan, and chitosan) filled with the clay mineral of natural origin, montmorillonite (MMT), were studied. The structure of intercalated/flocculated MMT distribution in the interpenetrating network of polysaccharide matrix was characterized using FTIR, X-ray diffraction, and SEM techniques. Swelling kinetics was investigated using the weight analysis, whereas the phase transition of water in the composition of hybrid hydrogels, by DSC method. Their biosafety was estimated using the Nelyubov method, germination test on cress (L. sativum) seeds, and metabolic fingerprinting of microbial communities and dehydrogenase assay. The obtained results indicated promising water-retaining properties of the synthesized materials. The hydrogels had a good sorption affinity for cadmium (Cd) ions confining bioavailability of the selected toxic heavy metal. They were safe for soil microorganisms and did not generate metabolic stress for them. Moreover, they did not reduce the viability of pea seeds. Thus, the development of biosafe hybrid hydrogel composites with a comprehensive, good effect on the environment could be considered as successful.

Separation of plant protection products from complex aqueous bodies using carbon-mineral composites incorporated with double metals (Ni/Mn or Ni/Fe)

Due to the extensive application of pesticides and their hazardous effects on organisms, there is an urgent need to remove them effectively from wastewater. Metal-incorporated carbon-mineral composites (Ni/Mn-CMC and Ni/Fe-CMC) described in this paper can certainly be applied for this purpose. They were synthesized by combining mechanochemical and pyrolytic processes and their physicochemical properties were investigated using numerous methods (SEM-EDS, N2 adsorption/desorption, XRD, surface charge, FTIR). Adsorption capacity towards diuron and carboxin with and without impurities commonly detected in natural ecosystems, cadmium ions or arsenite, was measured. The obtained results indicated that Ni/Fe-CMC is more efficient adsorbent of pesticides due to its well-developed surface. It was able to bind 158.34 mg g-1 of diuron and 133.58 mg g-1 of carboxin in the solutions, where only one pesticide was present. In turn, these values for the Ni/Mn-CMC sample were 126.49 mg g-1 and 102.08 mg g-1, respectively. It should be noted that the composites maintained their high adsorption capacity in the multicomponent solutions, i.e., containing both pesticide and metal ions. Then, the maximum reduction in pesticide adsorption was only 8.36. Ni/Mn-CMC and Ni/Fe-CMC were successfully regenerated with ethanol without changing their structure and adsorption capacity. Also, the extracts from investigated materials did not have negative impact on plant growth. This confirmed suitability of carbon-mineral composites for repeated multiple use without toxic effects to organisms.

Synthesis of xylan and lignin based hydrogels and their use as growth media for rice (Oryza sativa)

Different hydrogels were synthesised using lignin and xylan (extracted from rice straw) as the raw material, PVA as matrix template, citric acid, and succinic acid as crosslinkers and were structurally characterised by FT-IR and SEM analysis. Citric acid cross-linked hydrogels caused loose bonding between polymers and resulted in formation of large pores whereas succinic acid cross-linked hydrogels were observed to have less porosity and tight bonding network. The swelling ratio and reswelling capacity of hydrogels revealed that lignin hydrogels outperformed all other hydrogels. All the synthesised hydrogels were tested for their use as soil culture media ingredient for the germination of rice seedlings. All the hydrogels performed well in stress conditions as compared to normal conditions. Xylan/lignin hydrogel and lignin hydrogels performed best under stress conditions. These hydrogels could be used effectively as an ingredient of soil culture media owing to their tendency to absorb and retain water properly.

Comparison of Structural, Water-Retaining and Sorption Properties of Acrylamide-Based Hydrogels Cross-Linked by Physical and Chemical Methods

Two series of hydrogels based on acrylamide and its copolymers with acrylonitrile and acrylic acid were synthesized by two cross-linking methods - chemical (using N,N'-methylene bis-acrylamide) and physical (using montmorillonite (MMT)) ones. The structure of the gels was characterized by Fourier Transform Infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The swelling and sorption properties were analyzed as a function of both the monomer composition and the cross-linking method. The shift of the band corresponding to Si-O (995-1030 cm-1 ) confirmed the formation of intercalation structures for MMT-cross-linked gels. Moreover, physically cross-linked gels demonstrated a non-monotonic dependence of the swelling degree on the MMT concentration, and acrylamide-acrylic acid copolymer MMT-cross-linked gels showed pH sensitivity and the highest swelling degree of 150 g/g. The highest sorption capacity towards cadmium(II) ions was demonstrated by acrylamide-acrylic acid copolymer gels, both covalently cross-linked (30 mg/g) and MMT-cross-linked (8.9 mg/g).

Personalization of Minimally-Invasive Aesthetic Procedures with the Use of Ultrasound Compared to Alternative Imaging Modalities

Ultrasonography is a well-tolerated procedure that aids in the targeted esthetic therapies of special cutaneous regions, as well as in the prevention (vascular mapping, identification of previous filler, and others) and management of potential complications (vascular occlusion, external vascular compression, product misplacement or migration, inflammatory reactions, and others). It has lately been promoted as the first-line imaging tool to address injectables. In this article, we aim to review the evolving role of ultrasonography in cosmetic filler procedures, from the fundamental ultrasound characterization of cosmetic fillers to the ultrasound-enhanced detection and management of cosmetic filler complications, including ultrasound's role in hyaluronidase-guided injections for cosmetic filler dissolution. Furthermore, the paper explores the integral role played by ultrasound in enhancing the precision, efficacy, and safety of additional minimally invasive aesthetic techniques such as mesotherapy, radiofrequency, cryolipolysis, and polydioxanone procedures.