Gold catalysts screening in base-free aerobic oxidation of glucose to gluconic acid

Recent advances and synergistic effect of bioactive zeolite imidazolate frameworks (ZIFs) for biosensing applications

The rapid developments in the field of zeolitic imidazolate frameworks (ZIFs) in recent years have created unparalleled opportunities for the development of unique bioactive ZIFs for a range of biosensor applications. Integrating bioactive molecules such as DNA, aptamers, and antibodies into ZIFs to create bioactive ZIF composites has attracted great interest. Bioactive ZIF composites have been developed that combine the multiple functions of bioactive molecules with the superior chemical and physical properties of ZIFs. This review thoroughly summarizes the ZIFs as well as the novel strategies for incorporating bioactive molecules into ZIFs. They are used in many different applications, especially in biosensors. Finally, biosensor applications of bioactive ZIFs were investigated in optical (fluorescence and colorimetric) and electrochemical (amperometric, conductometric, and impedance) fields. The surface of ZIFs makes it easier to immobilize bioactive molecules like DNA, enzymes, or antibodies, which in turn enables the construction of cutting-edge, futuristic biosensors.

Catalytic conversion of cellulosic biomass to harvest high-valued organic acids

Catalytic conversion of biomass provides an alternative way for the production of organic acids from renewable feedstocks. The emerging process contains complex reactions and strategies to cut down those complex biogenic materials into target molecules. Here, we review the catalytic conversion of cellulosic biomass toward high-valued organic acids. This work has summarized the key controlling reactions which lead toward formic acid, glycolic acid, or sugar acids in oxidative conditions and the main pathways for lactic acid or levulinic acid in the anaerobic environment from cellulosic biomass and its derivatives. We evaluate and compare different strategies and methods such as one-pot and two-step conversion. Additionally, the optimization of catalytic reactions has been discussed to realize the design of C-C coupling reactions, the development of multifunctional materials, and new efficient system. In all, this article gives an insight guide to precisely convert cellulosic biomass into target organic acids.

Oxygen Vacancy-Induced Metal-Support Interactions in AuPd/ZrO2 Catalysts for Boosting 5-Hydroxymethylfurfural Oxidation

The construction of strong metal-support interactions in oxide-supported noble metal nanocatalysts has been considered an emerging and efficient way in improving catalytic performance in biomass-upgrading reactions. Herein, a citric acid (CA)-assisted synthesized ZrO2 layer with improved oxygen vacancy (Ov) concentrations on a natural clay mineral of halloysite nanotubes (HNTs) was designed. Moreover, AuxPdy/ZrO2@HNTs-zCA catalysts were prepared by loading AuPd bimetal and employed for aerobic oxidation of the lignocellulosic biomass-derived 5-hydroxymethylfurfural (HMF) platform to the bioplastic monomer 2,5-furandicarboxylic acid (FDCA) with water as the solvent. The results of catalytic experiments revealed that the Au3Pd1/ZrO2@HNTs-1.0CA catalyst exhibited excellent catalytic activity at 0.5 MPa O2, with a satisfactory FDCA yield of 99.5% and outstanding FDCA formation rate of 1057.9 mmol·g-1·h-1. The improved Ov concentration in the ZrO2 support enhanced the adsorption and activation ability of the catalyst for O2, and a higher Lewis acid concentration provided a stronger adsorption ability of the catalyst for reaction substrates. Besides, the synergistic effect of AuPd bimetallic nanoparticles steered the tandem oxidation of aldehyde and alcohol groups in HMF and accelerated the rate-determining step. More importantly, the relationship between the Ov concentration and catalytic performance also demonstrated that the enhanced catalytic activity for HMF oxidation was mainly attributed to the active interface of AuPd-ZrOx. This work offers fresh insights into rationally designing oxygen vacancy-driven strong interactions between the oxide support and noble nanoparticles for the catalytic upgrade of biomass platform chemicals.

Microwave-Assisted Base-Free Oxidation of Glucose with H2O2 on Gold- and Manganese-Containing SBA-15-Insight into Factors Affecting the Reaction Pathway

The aim of this work was to gain insights into the role of manganese in MnSBA-15 support for gold in the base-free glucose oxidation with H₂O₂ using a microwave reactor. MnSBA-15 (manganese-acidity source) and SBA-15 (for comparison) were modified with Au (2.2 wt. %) and Cu (for comparison). The physicochemical properties of the catalysts were investigated by XRD, N₂ ads/des, TEM, UV-vis, XPS, pyridine adsorption combined with FTIR, ATR-FTIR, and 2-propanol decomposition. The effects of the Mn presence in the support, Au NPs size that determines the number of active Au centers, and the Fermi energy (E_F), together with the effects of the pore size, reaction temperature, and time on the activity and selectivity of the applied catalysts were assessed and discussed. It has been demonstrated that the presence of Mn generated Lewis acid centers which did not participate in glucose and H₂O₂ adsorption, and thus, were not directly involved in the reaction pathway. Both reagents were adsorbed on gold nanoparticles. H₂O₂ was decomposed to molecular oxygen which oxidized glucose to gluconic acid (50-90% of glucose conversion depending on the reaction time and ~100% selectivity). The presence of manganese in MnSBA-15 was responsible for increased Au NPs size and only slightly influenced the negative charge on gold particles. To achieve effective activity a compromise between the number of active gold species and the level of E_F has to be reached (for 5.7 nm Au NPs).

A Comprehensive Review on the Use of Metal–Organic Frameworks (MOFs) Coupled with Enzymes as Biosensors

Several studies have shown the development of electrochemical biosensors based on enzymes immobilized in metal–organic frameworks (MOFs). Although enzymes have unique properties, such as efficiency, selectivity, and environmental sustainability, when immobilized, these properties are improved, presenting significant potential for several biotechnological applications. Using MOFs as matrices for enzyme immobilization has been considered a promising strategy due to their many advantages compared to other supporting materials, such as larger surface areas, higher porosity rates, and better stability. Biosensors are analytical tools that use a bioactive element and a transducer for the detection/quantification of biochemical substances in the most varied applications and areas, in particular, food, agriculture, pharmaceutical, and medical. This review will present novel insights on the construction of biosensors with materials based on MOFs. Herein, we have been highlighted the use of MOF for biosensing for biomedical, food safety, and environmental monitoring areas. Additionally, different methods by which immobilizations are performed in MOFs and their main advantages and disadvantages are presented.

Synthesis, Catalytic Properties and Application in Biosensorics of Nanozymes and Electronanocatalysts: A Review

The current review is devoted to nanozymes, i.e., nanostructured artificial enzymes which mimic the catalytic properties of natural enzymes. Use of the term "nanozyme" in the literature as indicating an enzyme is not always justified. For example, it is used inappropriately for nanomaterials bound with electrodes that possess catalytic activity only when applying an electric potential. If the enzyme-like activity of such a material is not proven in solution (without applying the potential), such a catalyst should be named an "electronanocatalyst", not a nanozyme. This paper presents a review of the classification of the nanozymes, their advantages vs. natural enzymes, and potential practical applications. Special attention is paid to nanozyme synthesis methods (hydrothermal and solvothermal, chemical reduction, sol-gel method, co-precipitation, polymerization/polycondensation, electrochemical deposition). The catalytic performance of nanozymes is characterized, a critical point of view on catalytic parameters of nanozymes described in scientific papers is presented and typical mistakes are analyzed. The central part of the review relates to characterization of nanozymes which mimic natural enzymes with analytical importance ("nanoperoxidase", "nanooxidases", "nanolaccase") and their use in the construction of electro-chemical (bio)sensors ("nanosensors").

Advances in catalytic routes for the production of carboxylic acids from biomass: a step forward for sustainable polymers

Polymers are ubiquitously present in our daily life because they can meet a wide range of needs and fields of applications. This success, based on an irresponsible linear consumption of plastics and the access to cheap oil, is creating serious environmental problems. Two lines of actions are needed to cope with them: to adopt a circular consumption of plastics and to produce renewable carbon-neutral monomers. This review analyses the recent advances in the chemocatalytic processes for producing biomass-derived carboxylic acids. These renewable carboxylic acids are involved in the synthesis of relevant general purpose and specialty polyesters and polyamides; some of them are currently derived from oil, while others can become surrogates of petrochemical polymers due to their excellent performance properties. Polyesters and polyamides are very suitable to be depolymerised to other valuable chemicals or to their constituent monomers, what facilitates the circular reutilisation of these monomers. Different types of carboxylic acids have been included in this review: monocarboxylic acids (like glycolic, lactic, hydroxypropanoic, methyl vinyl glycolic, methyl-4-methoxy-2-hydroxybutanoic, 2,5-dihydroxypent-3-enoic, 2,5,6-trihydroxyhex-3-enoic acids, diphenolic, acrylic and δ-amino levulinic acids), dicarboxylic acids (2,5-furandicarboxylic, maleic, succinic, adipic and terephthalic acids) and sugar acids (like gluconic and glucaric acids). The review evaluates the technology status and the advantages and drawbacks of each route in terms of feedstock, reaction pathways, catalysts and economic and environmental evaluation. The prospects and the new research that should be undertaken to overcome the main problems threatening their economic viability or the weaknesses that prevent their commercial implementation have also been underlined.

Gold-Based Nanoparticles on Amino-Functionalized Mesoporous Silica Supports as Nanozymes for Glucose Oxidation

The transformation of glucose represents a topic of great interest at different levels. In the first place, glucose is currently conceived as a green feedstock for the sustainable production of chemicals. Secondly, the depletion of glucose at the cellular level is currently envisioned as a promising strategy to treat and alter the erratic metabolism of tumoral cells. The use of natural enzymes offers multiple advantages in terms of specificity towards the glucose substrate but may lack sufficient robustness and recyclability beyond the optimal operating conditions of these natural systems. In the present work, we have evaluated the potential use of an inorganic based nanohybrid containing gold nanoparticles supported onto ordered mesoporous supports. We have performed different assays that corroborate the enzyme-mimicking response of these inorganic surrogates towards the selective conversion of glucose into gluconic acid and hydrogen peroxide. Moreover, we conclude that these enzyme-like mimicking surrogates can operate at different pH ranges and under mild reaction conditions, can be recycled multiple times and maintain excellent catalytic response in comparison with other gold-based catalysts.

Highly selective oxidation of glucose to gluconic acid and glucaric acid in water catalyzed by an efficient synergistic photocatalytic system

A TiO₂/HPW/CoPz composite is an excellent photocatalyst for selective oxidation of glucose to gluconic acid and glucaric acid in water.

Oxidation of lignocellulosic platform molecules to value-added chemicals using heterogeneous catalytic technologies

This minireview gives an overview about heterogeneous catalytic technologies for the oxidation of key platform molecules (glucose, 5-hydroxymethylfurfural, furfural and levulinic acid) into valuable chemicals.

Au/CeO2-ZnO/Al2O3 as Versatile Catalysts for Oxidation Reactions: Application in Gas/Liquid Environmental Processes

The present work showcases the versatility of nanogold systems supported on Zn-doped ceria when applied in two important environmental processes, the total CO oxidation, and the liquid phase oxidation of glucose to gluconic acid. In the CO oxidation the suitability of these materials is clearly demonstrated achieving full conversions even at sub-ambient conditions. Regarding the glucose oxidation our materials display high conversion values (always over 50%) and very importantly full or almost full selectivity toward gluconic acid-an added value platform chemical in the context of biomass upgrading routes. The key factors controlling the successful performance on both reactions are carefully discussed and compared to previous studies in literature. To our knowledge this is one of the very few works in catalysis by gold combining liquid and gas phase reactions and represents a step forward in the flexible behavior of nano gold catalysts.

Immobilization of Stabilized Gold Nanoparticles on Various Ceria-Based Oxides: Influence of the Protecting Agent on the Glucose Oxidation Reaction

The influence of the protecting agent’s nature on gold particle size and dispersion was studied in this work over a series of gold-based catalysts. CO and glucose oxidation were chosen as catalytic reactions to determine the catalyst’s structure–activity relationship. The nature of the support appeared to be the predominant factor for the increase in activity, as the oxygen mobility was decisive for the CO oxidation in the same way that the Lewis acidity was decisive for the glucose oxidation. For the same catalyst composition, the use of montmorillonite as the stabilizing agent resulted in better catalytic performance.

Advances in porous and nanoscale catalysts for viable biomass conversion

Solid catalysts with unique porosity and nanoscale properties play a promising role for efficient valorization of biomass into sustainable advanced fuels and chemicals.

Photocatalytic oxidation of glucose in water to value-added chemicals by zinc oxide-supported cobalt thioporphyrazine

Efficient photocatalytic oxidation of glucose into value-added chemicals was achieved by ZnO/CoPzS₈ composite in water, the presence of CoPzS₈ changed the glucose reaction pathway and glucaric acid was obtained in this photocatalytic system.

Nanostructured Metal Catalysts for Selective Hydrogenation and Oxidation of Cellulosic Biomass to Chemicals

Conversion of biomass to chemicals provides essential products to human society from renewable resources. In this context, achieving atom-economical and energy-efficient conversion with high selectivity towards target products remains a key challenge. Recent developments in nanostructured catalysts address this challenge reporting remarkable performances in shape and morphology dependent catalysis by metals on nano scale in energy and environmental applications. In this review, most recent advances in synthesis of heterogeneous nanomaterials, surface characterization and catalytic performances for hydrogenation and oxidation for biorenewables with plausible mechanism have been discussed. The perspectives obtained from this review paper will provide insights into rational design of active, selective and stable catalytic materials for sustainable production of value-added chemicals from biomass resources.

Products of sugar beet processing as raw materials for chemicals and biodegradable polymers

This paper presents an overview of alternative uses for products of sugar beet processing, especially sucrose, as chemical raw materials for the production of biodegradable polymers. Traditionally, sucrose has not been considered as a chemical raw material, because of its use in the food industry and high sugar prices. Beet pulp and beetroot leaves have also not been considered as raw materials for chemical production processes until recently. However, current changes in the European sugar market could lead to falling demand and overproduction of sucrose. Increases in the production of white sugar will also increase the production of waste biomass, as a result of the processing of larger quantities of sugar beet. This creates an opportunity for the development of new chemical technologies based on the use of products of sugar beet processing as raw materials. Promising methods for producing functionalized materials include the acidic hydrolysis of sugars (sucrose, biomass polysaccharides), the catalytic dehydration of monosaccharides to HMF followed by catalytic oxidation of HMF to FDCA and polymerization to biodegradable polymers. The technologies reviewed in this article will be of interest both to industry and science.

This paper presents an overview of alternative uses for products of sugar beet processing, especially sucrose, as chemical raw materials for the production of biodegradable polymers.

The Preparation of Hyaluronic Acid Nanoparticles from Aspicilia lichens Using Bifido Bacteria for Help in the Treatment of Diabetes in Rats In Vivo

Many common herbs and spices are claimed to have blood sugar lowering properties that make them useful for people with or at high risk of diabetes. The main of compounds of kiwifruit (Actinidia deliciosa), rhubarb (Rheum ribes), membrane inner of egg shell, wool of sheep, human fingernail (unguis), hyaluronic acid produced by the Bifidobacterium, and usnic acid of Aspicilia lichen were extracted by different methods. All compounds of the extract were divided into five groups. We used variables such as pH, different compounds, concentration, number of injections, and blood glucose monitoring in different situations. Our study, extracts changed to nanoform. The extract compounds and nanoparticles were analyzed by gas chromatography mass spectroscopy, Fourier transform infrared spectroscopy, hydrogen-1 nuclear magnetic resonance, and scanning electron microscope. The average size of the nanoparticles was found to be 55 nm. Five groups of nanoparticles were injected into rats, and they reduced their blood glucose levels significantly (statistical significance was declared at p < 0.05). The synthesized hyaluronic acid helped to treat diabetes in rats. Copyright © 2017 John Wiley & Sons, Ltd.