Glycerol Citrate Research Articles

New substrate for plant growth based on granite powder and biodegradable geomimetic composites obtained from bentonite-poly(glycerol citrate)

Granite powder (GP) alkaline waste of industrial origin that can provide nutrients for agricultural production. However, due to its high alkalinity it can reduce the availability of Fe and generate chlorosis in plants. In this work, the use of geomimetic composites mixed with GP has been proposed as an eco-friendly plant growth substrate. Thus, bentonite-poly(glycerol citrate) geomimetic composites (BPGC) were synthesized and added to GP. The effect on nutrient leaching, growth of Lolium perenne and physicochemical properties of substrates prepared were assessed. BPGC were synthesized by surface modification of bentonite with (3-aminopropyl)triethoxysilane and followed by polyesterification with glycerol and citric acid. Structural characterization by infrared spectroscopy, magnetic resonance and scanning electron microscopy allowed to verify that structural configuration mimics the structure of soil particles. BPGC showed a thermal degradation from ∼140 °C and a decrease on Tg as clay content in composite is increased. Leaching profiles of substrates produced from GP and BPGC showed the ability of mixture to interact with nutrients and reduce the losses of them, showing a greater tendency for retaining of potassium and phosphorus. Finally, the plant growth experiments showed no trend or relationship between the yield of Lolium perenne and the treatments assayed. Therefore, it is concluded that the addition of BPGC to GP modulated and improved the physicochemical properties of the substrates evidencing its potential application as amendment for the restoration of degraded soils, however, an improvement in the growth of the plants evaluated was not evident.

CTAB Surfactant Promotes Rapid, Efficient, and Simultaneous Removal of Cationic and Anionic Dyes through Adsorption on Glycerol/Citrate Polyester

The discharge of dye waste by industries has caused environmental impacts on water properties, aquatic species, and human life. The production of eco-friendly materials for dye removal from wastewater has gained increasing interest, particularly through adsorption, as it is an efficient method for removing pollutants. However, the selectivity and limited adsorption capacity of materials for simultaneously adsorbing cationic and anionic dyes make it challenging to address the prevailing dye effluent issue. In this work, a poly(glycerol citrate) polyester was prepared without a solvent, using microwave heating, and was combined with cetyltrimethylammonium bromide (CTAB) to modulate the simultaneous adsorption of cationic (Rhodamine B, RB) and anionic dyes (acid blue 113, AB and acid red 27, AR). The formation of the polyester was successfully confirmed by ATR-FTIR and the thermal properties were evaluated by TGA and DCS. In the presence of CTAB 5 mM, the material removes almost 100% of the dyes, reaching the kinetics equilibrium in 30 min following the Pseudo-second order model. Additionally, dye adsorption on the polyester in the presence of CTAB was described by the Freundlich isotherm model, indicating a heterogeneous polyester surface that promotes a multi-layer adsorption driven by electrostatic interaction and hydrogen bonds. The material showed an adsorption capacity of 73.7 ± 3.2, 82.1 ± 4.4, and 21.2 ± 0.6 mg/g for RB, AB, and AR, respectively. Our results provide evidence that the poly(glycerol citrate)/CTAB has a higher potential for application in wastewater treatment to remove both anionic and cationic dyes.

An eco-friendly composite hydrogel based on covalently crosslinked cellulose/poly (glycerol citrate) for thallium (Ι) removal from aqueous solutions

Cellulose/poly (glycerol citrate) reinforced with thiol-rich polyhedral oligomeric silsesquioxane and apple peel (POSS-SH@CAG-CEL/AP) was synthesized using gelation method in the presence of glutaraldehyde as a crosslinker agent and used as an efficient composite hydrogel for elimination of Tl(Ι) from aqueous solutions. This composite hydrogel and synthesized thiol-rich polyhedral oligomeric silsesquioxane were characterized by elemental analysis, FT-IR, NMR, TGA, and FE-SEM techniques. The effects of synthetic and environmental parameters on the adsorption capacity of the composite hydrogel were investigated and it was found that thiol-rich polyhedral oligomeric silsesquioxane has improved the hydrogel properties including the Tl(Ι) uptake and the thermal stability. The maximum adsorption capacity of 352.3 mg g−1 was obtained within 30 min under optimum reaction conditions. A typical Langmuir adsorption isotherm with was observed for adsorption of Tl(I) onto POSS-SH@CAG-CEL/AP and pseudo-second-order kinetic model provided the best correlation between experimental data. Thermodynamic studies showed that the Tl(I) adsorption was spontaneous process and exothermic. Also, the reusability tests confirmed that the POSS-SH@CAG-CEL/AP can be reused for four times without any remarkable change in its adsorption capacity. Thus, this reusable biobased composite hydrogel can be an ideal candidate for elimination of Tl(I) from aqueous solutions.

Biobased poly(glycerol citrate) synthesis optimization via design of experiments

AbstractNowadays, glycerol polyesters are willingly studied, due to their potential to use in tissue engineering and drug delivery systems. Poly(glycerol citrate) is a quite new material that could have very interesting properties because of the easy formation of three‐dimensional hydrophilic networks. Moreover, both glycerol and citric acid are commonly used chemicals in the food and pharmaceutical industry. They are cheap, well available, and well‐known substances. In this work poly(glycerol citrate) was synthesized in bulk polycondensation with water removal. The polyester structure was widely characterized by FTIR, NMR, GPC, and the end group titration methods. The synthesis procedure was optimized and described via five mathematical models with the use of the design of experiments. The presented method was developed for further industrial use and allows for avoiding gelling phenomena. Based on this work, poly(glycerol citrate) could be obtained with desired properties, moreover, the process is prepared for scaling‐up.

Poly(glycerol citrate)‐polylactide nonwovens toward tissue engineering applications

AbstractIn 2002, Robert Langer proposed that new polyester for tissue engineering should have good mechanical properties followed by: covalent bonding (as crosslinking) and hydrogen‐bonding interactions; and should be elastic like rubber materials due to three‐dimensional network structure. Considering these hypotheses, a polyester made of glycerol and citric acid was designed in this work. Poly(glycerol citrate) should be attractive for tissue engineering because both glycerol and citric acid, taking part in natural human metabolic pathways; and due to the reactant's functionality, 3D networks should be produced easily. Moreover, the reagents are cheap, available, and often used in the food and pharmaceutical industries. In this work, poly(glycerol citrate) was synthesized and then used with PLA for creating porous nonwovens by electrospinning. Produced materials were tested for possible application in the field of tissue engineering. The obtained materials have properties similar to collagen fibers, but still, require refinement for medical applications.

Environmentally friendly adhesives derived from glycerol-based polymers

Biodegradable, renewable, and environmentally friendly glycerol-based wood adhesives were synthesized through polycondensation reaction between dicarboxylic acids (sebacic and citric acid) and glycerol using different molar ratios, i.e. poly(glycerol sebacate) – PGS, poly(glycerol citrate-co-sebacate) – PGCS, and poly(glycerol citrate) – PGC. Thermal properties of the synthesized polymers were evaluated after cross-linking. Results showed that thermal stability was influenced by polymer molecular structure, being lower for PGC due to the presence of quaternary carbons of citric acid. Differential scanning calorimetry analyses showed an intermediate glass transition for the copolymer in comparison with homopolymers. Tensile shear strength tests showed that the presence of citric acid in the polymer improves adhesion and reduces adhesive flexibility, contrary to what happens to polymers with sebacic acid. This behavior was also proved through morphological analyses of the fracture surface. Adhesives with tailor-made properties were produced from glycerol, opening up new revenues for a by-product of the biodiesel production chain.

Kinetics of Polycondensation of Citric Acid with Glycerol Based on a Genetic Algorithm

Poly(glycerol citrate) is a biodegradable aliphatic polyester made of citric acid and glycerol. Because of the high functionality of the reactants, citric acid—4 and glycerol—3, there are many possibilities for creating different polymer chain structures. In this work, the polycondensation of citric acid with glycerol and its kinetics were studied through the kinetic model, allowing for estimation of relevant kinetic constants values for the first time with the employment of a genetic algorithm. The proposed kinetic model is multidimensional and contains eight parameters. The values of kinetic constants of the reaction included in our kinetic model were estimated. Relevant Arrhenius plots justify the applied model because of values of the R2 coefficient of nearly 1.0. Considerations on the competitiveness of various reactionary acts are presented.

Protoenzymes: The Case of Hyperbranched Polymer-Scaffolded ZnS Nanocrystals.

Enzymes are biological catalysts that are comprised of small-molecule, metal, or cluster catalysts augmented by biopolymeric scaffolds. It is conceivable that early in chemical evolution, ancestral enzymes opted for simpler, easier to assemble scaffolds. Herein, we describe such possible protoenzymes: hyperbranched polymer-scaffolded metal-sulfide nanocrystals. Hyperbranched polyethyleneimine (HyPEI) and glycerol citrate polymer-supported ZnS nanocrystals (NCs) are formed in a simple process. Transmission electron microscopy (TEM) analyses of HyPEI-supported NCs reveal spherical particles with an average size of 10 nm that undergo only a modest aggregation over a 14-day incubation. The polymer-supported ZnS NCs are shown to possess a high photocatalytic activity in an eosin B photodegradation assay, making them an attractive model for the study of the origin of life under the “Zn world” theory dominated by a photocatalytic proto-metabolic redox reaction network. The catalyst, however, could be easily adapted to apply broadly to different protoenzymatic systems.

Synthesis and Characterization of Glycerol Citrate Polymer and Yttrium Oxide Nanoparticles as a Potential Antibacterial Material

Synthesis and Characterization of Glycerol Citrate Polymer and Yttrium Oxide Nanoparticles as a Potential Antibacterial Material

Biodegradable nanocomposite of glycerol citrate polyester and ultralong hydroxyapatite nanowires with improved mechanical properties and low acidity

Glycerol citrate polyester based on the condensation of glycerol and citric acid has a great potential in biomedical applications owing to biocompatible monomers and biodegradation properties. However, the applications of glycerol citrate polyester are impaired by its poor mechanical properties and high acidity caused by citric acid produced in the degradation process. In this work, a new kind of nanocomposite has been developed using ultralong hydroxyapatite (HAP) nanowires as the “skeleton”, and strongly bound glycerol citrate polyester as the “muscle”. The ultralong HAP nanowires interweave with each other to form a three-dimensional nanoporous network, and glycerol citrate polyester is homogeneously distributed in the nanoporous network. Owing to the reinforcement of ultralong HAP nanowires, the mechanical properties of the as-prepared nanocomposite are significantly improved compared with the pure glycerol citrate polyester, and the tensile strength even reaches to the level of human cortical bones. Furthermore, the acidity of the aqueous solution after degradation is neutralized by the reaction between citric acid and ultralong HAP nanowires, and the pH value can be stabilized. The as-prepared nanocomposite can solve some problems of the pure glycerol citrate polyester, and shows promising applications in the biomedical field.

Transparent Composites Made from Tunicate Cellulose Membranes and Environmentally Friendly Polyester.

A series of optically transparent composites were made by using tunicate cellulose membranes, in which the naturally organized cellulose microfibrillar network structure of tunicate tunics was preserved and used as the template and a solution of glycerol and citric acid at different molar ratios was used as the matrix. Polymerization through ester bond formation occurred at elevated temperatures without any catalyst, and water was released as the only byproduct. The obtained composites had a uniform and dense structure. Thus, the produced glycerol citrate polyester improved the transparency of the tunicate cellulose membrane while the cellulose membrane provided rigidity and strength to the prepared composite. The interaction between cellulose and polyester afforded the composites high thermal stability. Additionally, the composites were optically transparent and their shape, strength, and flexibility were adjustable by varying the formulation and reaction conditions. These composites of cellulose, glycerol, and citric acid are renewable and biocompatible and have many potential applications as structural materials in packaging, flexible displays, and solar cells.

A size-controlled synthesis and characterization of mixed monolayer protected silver-S-(CH2)11-NHCO-coumarin nanoparticles and their Raman activities

Abstract

Glycerol citrate polyesters produced through heating without catalysis

AbstractThe influence of various heating methods without catalysis to prepare polyesters from citric acid : glycerol blends were studied. In the presence of short‐term microwave treatments, i.e., 60 s at 1200 W, blends of glycerol and citric acid invariably formed solid amorphous polyesters. Fourier transform infrared spectroscopy showed that citric acid and glycerol blends can form highly stable polymers composed of ester bonds. The glycerol citrate polyester polymers exhibited the least degradation in water, more in acid solutions (0.1–1.0M HCl), and the most deterioration in strong alkaline solutions (0.1–1.0M NaOH) after 72 h soakings. Polyesters of glycerol and citric acid were studied with differential scanning calorimetry and thermal gravimetric analysis. The polyesters were found to be thermally stable (up to 313°C). © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Instrumental Physical Analysis of Microwaved Glycerol Citrate Foams

Solid glycerol citrate polyester polymeric foams generated by microwave heating were further cured in a conventional oven at 100 °C for 0, 6, 24, 48, or 72 h and their physical properties were tested. Curing glycerol citrate polyesters resulted in decreased moisture content (MC), altered color, increased hydrated polymer weight loss (HWL), and increased polymer oven weight loss (OWL). Polyester polymer samples were evaluated for firmness and springiness employing a texture analyzer (Model TA/TX2i). Oven curing increased polymer firmness and springiness. For example, firmness and springiness in 48 h cured samples increased 202 and 143%, respectively, when compared to uncured controls. High correlations were found comparing OWL, MC, HWL, firmness, and springiness. Compression molded samples obtained from ground cured and non-cured polymers were evaluated for tensile strength, elongation and Young’s modulus using the Instron universal test machine (Model 4201). Curing promoted higher tensile strengths and elongation but did not affect Young’s modulus values. High correlations were found between springiness, firmness, tensile strength, and elongation. The texture analyzer was shown to have merit in the preliminary evaluation of the glycerol citrate polyester polymers.

An improved method for the reconstitution of frozen red blood cells.

Abstract. Continuous flow dialysis of red cells which have been stored frozen at –20 to –25°C in 40% glycerol citrate solution improves the percentage recovery and stability of the red cell samples and reduces the time of the recovery procedure.

An Improved Method for the Reconstitution of Frozen Red Blood Cells

Continuous flow dialysis of red cells which have been stored frozen at -20 to -25 °C in 40% glycerol citrate solution improves the percentage recovery and stability of the red cell samples and reduces the time of the recovery procedure.