Combination Of Citric Acid Research Articles

In vitro Ascertainment of Interactions between Kanamycin and Adjuvants against Various Bacterial Species

Background: In recent times, there has been incontrovertible evidence regarding the propensity of various bacteria that barge through the immune system of an already debilitated individual. In this regard, combination therapy presents us with a more effective approach than conventional monotherapy. A specific combination of antibiotics exhibits a synergistic antibacterial effect, which can be seen with kanamycin, which shows moderate antibacterial activity alone but acts synergistically with particular adjuvants, displaying a high degree of antibacterial activity Objective: This study aimed to carry out an in vitro evaluation of the interaction between kanamycin and adjuvants against various bacterial species. Methods: The interaction between kanamycin and adjuvants against various bacterial isolates was determined by checkerboard assay, and the synergistic interactions were further evaluated by time-kill kinetic assay under in vitro settings. Results: The interaction between kanamycin and citric acid was found to be synergistic against all strains of E. coli. Both kanamycin and citric reduced their MICs by at least 4 fold in combination. This synergistic interaction was further confirmed by the time-kill kinetic assay. The result of time kill kinetic assay of combination revealed that at MIC, there was a 2.36 log10 CFU/ml reduction compared to kanamycin (the most active antimicrobial agent alone), at 24 hours at 2 fold MIC, 2.41 log10 CFU/ml reduction was seen in comparison to kanamycin at 24 hours at its one fold MIC. For other bacterial species, the combination of citric acid and kanamycin showed additive or indifferent interactions. In the case of our second combination (kanamycin and sodium salicylate), all the bacterial species displayed additive and indifferent interaction. Conclusion: It has been concluded that the combination of kanamycin and citric acid (adjuvant) demonstrated a remarkable synergistic interaction against E. coli.

Enhancement of terephthalic acid recovered from PET waste using a combination of citric acid and dimethyl sulfoxide extraction

This study aimed to develop an eco-friendly, cost-efficient, and practically viable method for extracting terephthalic acid (H2BDC) from polyethylene terephthalic (PET) waste. Dimethyl sulfoxide (DMSO) was combined with either citric acid (C6H8O7) or H2SO4 to enhance the particle size of H2BDC, and the optimum conditions during the acidification step were determined. Additionally, response surface methodology was employed to examine the influence and interaction of extractant (NaOH) concentration, hydrolysis temperature, and time on the optimal H2BDC yield and recovery ratio. Experimental results demonstrated that NaOH concentration significantly impacted both H2BDC yield and recovery ratio, surpassing the effects of hydrolysis temperature and time. Under optimal conditions involving a temperature of 200 °C and a 12 h reaction time with 5% NaOH, the model predicted a 100% yield and recovery ratio, which closely matched the experimental results of 99% and 100% for yield and recovery ratio, respectively. To enhance particle size, a combination of DMSO and C6H8O7 was more effective than H2SO4. The maximum particle size achieved was 57.4 µm under the following optimum conditions: premixing 5 M C6H8O7 with DMSO at a 35:75 mL ratio and maintaining a reaction temperature of 75 °C for 40 min. The study demonstrated the stability and consistency of the method. The H2BDC yield remained between 96 and 98% with high purity over eight consecutive cycles of using the DMSO and C6H8O7 mixture. The findings highlight the importance of integrating C6H8O7 and DMSO to enhance H2BDC quality, meeting commercial product criteria with evidence of high purity and large particle size. This method presents a promising solution for extracting H2BDC from PET waste, with potential implications for the recycling industry and a positive environmental impact.

Understand the Stabilization Engineering of Ascorbic Acid, Mapping the Scheme for Stabilization, and Advancement.

Vitamin C is extensively used in cosmetic formulation, howbeit stability is the supreme demerit that limits its use in beautifying products. Numerous techniques are being employed to inhibit the degradation of vitamin C caused by formulation components to facilitate the use in skin rejuvenating products. Diverse materials are being exercised in formulation to stabilize the ascorbic acid and ingredients selected in this formulation composition help for stabilization. The initial stable prototype is developed and further optimization is accomplished by applying the design of experiment tools. The stable pharmaceutical formulations were evaluated for the evaluation parameters and designated as two optimized formulations. The analytical method for the assay of ascorbic acid from the United States pharmacopeia and the related substance method from European pharmacopeia has been modified to be used for cream formulation. The DoE design exhibited that the stability of formulation is impacted by citric acid and tartaric acid but not by propylene glycol and glycerin. The analysis results of topical formulations for the evaluation parameter exhibited satisfactory results. The in-vitro release study method has been developed, optimized, and validated to fit the analysis. The in-vitro studies have been performed for selected compositions and both the formulation has similar kinds of release patterns. The stability study as per ICH guidelines exhibited that the product is stable for accelerated, intermediate, and room-temperature storage conditions. The optimized formulation shows constant release and permeation of ascorbic acid through the skin. The formulation with the combinations of citric acid, tartaric acid, and tocopherol is more stable and the degradation of vitamin C has been reduced significantly. The beaucoup strategies in the unique composition help to protect the degradation by inhibiting the multitudinous degradation pathways.

Reduction of surface treatment time by combination of citric acid and ascorbic acid while restoring shear bond strength of metal brackets bonded to bleached enamel: a pilot study

BackgroundTo investigate the effect of a 50% ascorbic acid with 50% citric acid solution on the immediate shear bond strength (SBS) of metallic brackets after tooth bleaching. The enamel etching pattern and the required quantity of these combined acids as antioxidants following 35% hydrogen peroxide (HP) bleaching were also determined.MethodsThe stability of the solution at room temperature was assessed at various time intervals. Fifty teeth were randomly divided into five groups: non-bleached (G1), bleached then acid etched (G2), bleached followed by a 10-minute treatment with 10% sodium ascorbate and acid etched (G3), 5-minute treatment with 50% ascorbic acid (G4), and 5-minute treatment with a combination of 50% ascorbic acid and 50% citric acid (G5). Groups G2, G3, G4 and G5 were bleached by 35% HP gel for a total of 32 min. Acid etching in groups G1, G2, and G3 was performed using 37% phosphoric acid (Ormco®, Orange, CA, USA) for 15 s. In all groups, metal brackets were immediately bonded using Transbond™ XT primer and Transbond™ PLUS adhesive, with light curing for 40 s. The SBS was tested with a universal testing machine, and statistical analysis was conducted using one-way ANOVA followed by Tukey’s HSD test. The level of significance was set at p < 0.05 for all statistical tests.ResultsStability tests demonstrated that the combined acids remained effective for up to 21 days. Group G5 significantly increased the SBS of bleached teeth to the level of G1 (p < 0.05), while G3 did not achieve the same increase in SBS (p > 0.05). SEM analysis revealed enamel etching patterns similar to those of both control groups (G1 and G2). Kinetic studies at 6 min indicated that the antioxidation in G5 reacted 0.2 mmole lower than in G3 and G4.Conclusion5-minute application of the combined acids enhanced the SBS of bleached teeth comparable to unbleached teeth. The combined acids remain stable over two weeks, presenting a time-efficient, single-step solution for antioxidant application and enamel etching in orthodontic bracket bonding.

Formulation of Effervescent Tablet from Kelulut Bee (Trigona sp.) Pollen from East Kalimantan

Since the beginning of human history, bee honey has been used by humans. However, there are also other bee products such as bee pollen (BP), royal jelly, propolis, and beeswax. Previous research has identified that pollen contains amino acids, lipids, flavonoids, micronutrients and many fat-soluble vitamins such as vitamins A, E and D, as well as water-soluble vitamins such as vitamins B1, B2, B6 and C. The objective of this study is to formulate bee pollen as effervescent tablet. The method in this study used alkaline granulation which requires an oven process for 24 hours and the use of a combination of sodium bicarbonate with citric acid. Three formulas were optimized in this study. The stability test results showed that formula number 3 has an average moisture content of 0.5696±0.6154%, and average flow rate of 0.67±0.02054 g/sec, the average compressibility in formula number 1 is 0.046±0.0452%. Overall, it is also known that formula number 2 has the smallest dissolution time compared to other formulations. The effect of the combination of citric acid and sodium bicarbonate used in the formulation of effervescent tablets from bee pollen on the physical quality of the tablets, namely friability, hardness, and dissolving time, the higher levels of citric acid and sodium bicarbonate used do not have a significant effect on friability, hardness, and time dissolving effervescent tablets from bee pollen from kelulut bees (Trigona sp).

Effect of a Combination of Citric Acid and Selenium Nanoparticles on Male Rats Nephrotoxicity Caused by Carbon Tetrachloride

Background: To investigate the therapeutic effects of a combination of citric acid and Se-NPs against carbon tetrachloride (CCl4)-induced renal damage in rats. Methods: Twenty-four rats were divided into three groups (n = 8 each). Group 1 (control) received the vehicle, while Group 2 received a single dose of 1 ml/kg CCl4 in liquid paraffin (1:1 volume) via intraperitoneal injection. Group 3 was administered a single dose of 1 ml/kg CCl4 in liquid paraffin and then treated twice a week for three weeks with a dose of 2.5 mg/kg Se-NPs. One-way ANOVA and Tukey’s method were used to compare the overall effects of each treatment. Result: CCL4 elevated MDA levels and decreased GSH levels in group 2 animals compared with those in the control group. Se-NPs significantly restored the oxidative stability in group 3. We found that CCL4 significantly increased its effect on renal function, whereas Se-NPs restored the renal structure affected by CCL4. As a result, Se-NPs can potentially reduce the markers of renal injury caused by CCl4, while also restoring oxidative stability and renal structure and function.

Extraction and selective precipitation of metal ions from LiCoO2 cathodes using citric acid

The most common methods for recycling Lithium-Ion Batteries use strong mineral acids and hydrogen peroxide. Alternative acids and reducing agents are currently being studied to reduce the environmental impact of these batteries recycling processes. This research provides a practical pathway for recycling batteries using citric acid as a sustainable lixiviant. The combination of citric acid and copper as extractant and reductant agents, respectively, to selectively recover lithium and cobalt from LiCoO2 has been studied. Leaching with 2 M citric acid and 70 °C in the presence of copper resulted in a recovery of nearly 100 % Li and around 81 % Co, contained in the liquid phase and the solid precipitate formed during the experiments. Cobalt solubility experiments and solid characterization were performed to understand further the formation of cobalt-citrate solid species detected. Experimental and theoretical results suggest that the precipitate could be identified as CoHCitrate, associated with the selective recovery of cobalt from LiCoO2. Results obtained in this work indicate that citric acid could be used not only as an extractant agent but also as a precursor to precipitate metals from LIBs, improving the efficiency and selectivity of recycling processes.

Performance improvement of magnesium oxysulfate cement by the combination of additives

Magnesium oxysulfate cement (MOS) is a lightweight and low-alkalinity inorganic cementitious material that has been widely used in the construction field. However, MOS required a longer setting time in certain conditions, which had received less research attention. This article explores the influence of various single and composite additives on the setting time and water resistance of MOS composite materials. Additionally, it delves into how the composition of active groups within these additives and fluctuations in pH levels during the hydration process impact the performance of MOS. The findings showed that composite additives significantly prolonged the initial setting time of MOS and improved the early compressive strength and water resistance. The combination of citric acid (CA) and sodium tripolyphosphate (SHPP) exhibited the best modification effect. After modification, the initial setting time increased by 215.4 % compared with pure MOS, and the compressive strength increased by 112.8 % after curing for 28 days. The setting time and mechanical strength of MOS composites could be regulated by adjusting the pH during hydration and its chelating effect on Mg2+, providing theoretical support for the broad application of MOS composites.

Tensile Strength Improvements of Ramie Fiber Threads through Combination of Citric Acid and Sodium Hypophosphite Cross-Linking

Ramie (Boehmeria nivea) is believed to be one of the strongest natural fibers, but it still remains behind synthetic materials in terms of tensile strength. In this study, ramie materials were prepared to evaluate the modification crosslinking effect of natural fiber. The aim is to optimize various concentrations of citric acid (CA) crosslinking by adding Sodium hypophosphite (NaPO2H2), which is activated at different temperatures, to obtain the highest tensile mechanical strength. This crosslinking effect has been confirmed by FTIR to show the esterification process in the molecular structure of cellulose. The changes in the character of the fiber surface were analyzed by SEM. The tensile strength increased from 62.33 MPa for 0% CA to 124–172.86 MPa for decorticated fiber with a CA concentration of 0.75–1.875% (w/w). A significant increase in tensile strength was observed more than 19 times when CA/SHP 1% was treated at an activation temperature of 110 °C with a superior tensile strength of 1290.63. The fiber crosslinked with CA/SHP should be recommended for application of Natural Fiber Reinforced Polymer Composite (NFRPC), which has the potential to use in functional textile and industrial sector automotive or construction.

Complexation leaching of critical and strategic metals from nickel converter slag using organic acids

Nickel converter slag is a waste product formed during the converting process in nickel production. In recent times the processing of nickel converter slag has gained attention as a secondary source of cobalt (Co) and nickel (Ni). Nickel and cobalt are considered critical and strategic metals that are essential for nations’ economy and defence, as well as high-technology industry. In particular, Co and Ni can be utilised in the batteries, superalloys, and automobiles. Extraction of critical and strategic metals from slag can be categorised as technospheric mining. In this study, the slag was characterised using combination of XRF, XRD, ICP-OES, FESEM and TIMA for better understanding of deportment of Ni and Co and texture of Ni converter (CV) slag. Complexation leaching by using a combination of citric acid and EDTA was undertaken to extraction by using the leaching agent and complexing agent. The preliminary test showed the most promising result. The leaching experiment was carried out with various parameters such as the reagent concentration, temperature, particle size, and pulp density. The optimum condition for extracting Co and Ni from CV slag is following; citric acid 1 M, EDTA 0.3 M, 80 °C, 6 hr, pulp density 2.5% (w/v), − 75 μm and 250 rpm, which recovered 85.29% of Co and 59.85% of Ni.

Synthesis of Some Distinct Curcumin-Based Pyrano [2,3-D] Pyrimidines with Barbituric Acid, Cinnamaldehyde, and Benzaldehyde

Curcumin is a powerful radical oxygen scavenger. The modification of of curcumin’s α, β-unsaturated 1,3-diketone moiety can be carried out to improve its physicochemical stability and functionality. This research aimed to conduct a modification of curcumin structure and to study the antioxidant activity of the modified curcumin-based compound. The modified curcumin made from a combination of benzaldehyde and cinnamaldehyde, using barbituric acid and combination of citric acid as catalyst and ethanol as solvent. The combination of ethanol solvent and 20 mmol% citric acid catalyst produce the highest yield of curcumin product which has a yield of 99.3581±0.2873% and was chosen as the best combination for the next modification using different β-diketone compounds. In the following stage, the mixture was reacted with either benzaldehyde or cinnamaldehyde. Yield, TLC, and antioxidant activity parameters were assessed for all modified products and were accompanied by their characterization using UV-Vis spectrophotometry. This study showed that curcumin cinnamaldehyde had a yield of 47.4831±2.7032%, a maximum wavelength of 416 nm, and antioxidant activity of IC50 18.2130±2.8766 mg/L with a molecular mass of 594 m/z. Keywords: antioxidant activity, benzaldehyde, cinnamaldehyde, curcumin, dimedone, modification

Technospheric mining of critical and strategic metals from nickel slag – Leaching with citric acid and hydrogen peroxide

Critical and strategic metals (CSMs), such as cobalt (Co) and nickel (Ni), are fundamental components of the high technology industry. Securing the supply of CSMs is fast becoming a priority for nations. Thus, secondary sources such as mine wastes, slags, tailings, and residues are being exploited to extract CSMs since they contain notable amounts of those metals. Recovering valuable metals from secondary sources can be categorised as technospheric mining. In this study, the extraction of cobalt and nickel from nickel slag was examined using a combination of an organic acid, citric acid, and hydrogen peroxide as the oxidant. Optimum conditions consisted of 1 M citric acid, 0.5% (v/v) hydrogen peroxide, at a temperature of 60 °C, a pulp density of 2.5%, a particle size of −100 + 75 μm, and an agitation speed of 400 rpm, for a period of 6 h. At the optimum conditions, 84.0% Ni and 91.7% Co were extracted from flash furnace (FF) slag, and 65.0% Ni and 99.1% Co from converter (CV) slag. It is expected that a combination of citric acid and hydrogen peroxide created peroxycitric acid in the solution, which is a strong oxidant and a key factor in the dissolution of the metals. The leach residue from FF slag showed a porous surface resulting from preferential dissolution within the slag structure. The residue from the converter (CV) slag mainly consisted of magnetite as a result of the dissolution of fayalite (Fe2SiO4). The kinetic studies demonstrated that the dissolution of Ni and Co from FF slag is controlled by diffusion. On the other hand, a rate controlling factor for Ni from CV slag is mixed control and for Co is a chemical reaction. Based on the temperature varied experiments, the calculated activation energy for Ni and Co from FF slag were 34.4 kJ/mol and 27.6 kJ/mol, respectively. The activation energies for the leaching of Ni and Co from the CV slag were 16.1 kJ/mol and 23.7 kJ/mol, respectively.

Acrylamide and 5-Hydroxymethylfurfural in Synthetic Sugar Cane Syrup: Mitigation by Additives.

The ability of additives to reduce the formation of acrylamide in simulated sugar cane syrups was investigated. Organic acids, B vitamins, and inorganic salts were added individually and in combination to simulated thickened cane juice, and the mixtures were heated at 120 °C for 30 min. Calcium chloride (1%), citric acid (0.1%), and vitamin B3 (0.1%) were the most effective individual additives from each chemical family. The effects of CaCl2 (0-1%), citric acid (0-0.125%), and vitamin B3 (0-0.1125%), when added in combination, on the concentrations of acrylamide and hydroxymethylfurfural (HMF) were studied using a Box-Behnken design. Combinations of all three additives lowered the acrylamide production, but only the combination of citric acid and vitamin B3 had a significant synergistic effect. However, all these additives stimulated the production of HMF, and no significant interactive effect between pairs of additives on HMF production was observed. Calcium chloride stimulated the formation of HMF most strongly. These results indicate that certain combinations of these additives effectively reduce acrylamide formation, but they also lead to an increase in the formation of HMF in sugar syrup.

Cost-effective and eco-friendly copper recovery from waste printed circuit boards using organic chemical leaching

Electronic waste generation is indeed a global concern; therefore, appropriate management and recycling are becoming highly significant. Printed circuit boards (PCBs) are significant portion of e-waste; contains a large number of valuable metals, rendering this material an important recovery resource. Among all other metals, the high Copper concentration of PCB residues, which is often ten times higher than that of rich-content rocks, makes these residues an appealing secondary source of Cu recovery. The primary goal of this study is to develop a simple and economical method for recovering Cu from waste PCBs. To leach metals, a combination of citric acid, acetic acid, and hydrogen peroxide (H2O2) was utilized. The influence of systemic factors such as citric acid concentration, acetic acid concentration, and H2O2 concentration on Cu leaching process was investigated. The results proved that the combination of citric acid, acetic acid, and H2O2 has increased the leaching efficiency of copper. More copper was dissolved when leaching with 0.5–1.5 M citric acid, 2.5–7.5%, and 2.5–7.5% H2O2 at 30 °C; however the individual acids produces less amount of Cu such as 26.86 ppm, 22.33 ppm, and 6.28 ppm whereas, high amount of Cu is obtained from the leaching solution containing 1 M citric acid, 5% acetic acid and 5% H2O2 with 325.89 ppm respectively. Thus, the combination of these acids and can be used as standardized method for leaching of Cu. These findings suggest that organic acids can replace inorganic acids as eco-friendly lixiviants for waste management.

Efficacy of marigold (Tagetes erecta L.) for the treatment of tannery and surgical industry wastewater under citric acid amendment: a lab scale study.

Contamination of land and aquatic ecosystems with heavy metals (HMs) is a global issue having the persistent potential to damage the quality of food and water. In the present study, Tagetes erecta L. plants were used to assess their potential to uptake HMs from wastewater. Plants were grown in soil for 20days and then transplanted in hydroponic system containing Hoagland nutrient solution. After more than 15days of growth, plants were then subjected to wastewater from tannery and surgical industries in different concentrations ranging from 25 to 100% in combination of citric acid (5 and 10mM). After 6weeks of treatment, plants were collected and segmented into roots, stem, and leaves for characterizing the morphological properties including plant height, roots length, fresh and dry mass of roots, stem, and leaves. For evaluation of the effect of wastewater on the plants, photosynthetic pigments; soluble proteins; reactive oxygen species (ROS); antioxidant enzymes SOD, POD, CAT, and APX; and metal accumulation were analyzed. Application of industrial wastewater revealed a significant effect on plant morphology under wastewater treatments. Overall growth and physiological attributes of plant decreased, and metal accumulation enhanced with increasing concentration of wastewater. Similarly, the production of ROS and antioxidant enzymes were also increased. Chlorophyll, protein content, and enzyme production enhanced with CA (5 and 10mM) mediation; however, ROS production and EL were reduced. Metals analysis showed that the maximum accumulation of Pb was in roots, while Cr and Ni in the stem which further increased under CA mediation. Overall, the metal accumulation ability was in the order of Pb > Ni > Cr under CA.

Enhancement of heavy metals desorption from the soil by eddy deep leaching in hydrocyclone

An eddy deep leaching technology was developed in this paper to address the challenge of treating heavy metal contaminants in industrial mining areas. The desorption effect of As, Cd, Sb and Pb was investigated utilizing chemical leaching and physical eddy techniques. It was found that the heavy metals concentration increased with decreasing particle size. The highest proportion of Cd in the form distribution of soil was in the bound to iron and manganese oxides, while the maximum proportion of As, Sb and Pb were in the residual. The optimal solid-liquid ratio of the hydrocyclone was 1:20, and the corresponding separation efficiency and flow rate were 84.7% and 1.76 m3/hr, respectively. The grade efficiency of soil particle separation increases with particle size and exceeds 99% for particles above 1,000 µm. Leaching experiments have revealed that oxalic acid (OA) and a combination of oxalic acid and EDTA (OAPE) were more efficient than citric acid (CA) and a combination of citric acid and EDTA (CAPE) for the desorption of heavy metals, respectively. The comparison of OAPE and eddy leaching found that the latter improved the desorption efficiency by 9.4%, 7.5%, 7.2% and 7.8% for As, Cd, Sb and Pb compared to the former, respectively. The results demonstrated that the eddy leaching technique could further enhance the desorption efficiency of heavy metals. It is expected to provide technical support for soil remediation with reduced usage of leaching agents.

Inhibition of acrylamide and 5‐hydroxymethylfurfural formation in French fries by additives in model reaction

AbstractAcrylamide (AA) and 5‐hydroxymethylfurfural (HMF) are Maillard reaction products that are formed during frying; they are toxic and are considered a potential health risk due to their high consumption levels in western diets. The purpose of this study was to evaluate various strategies for the formation of AA and HMF in French fries. HMF was quantified with a UV‐spectrophotometer and AA was determined by high‐pressure liquid chromatography (HPLC) with the help of diode array detection (DAD) detector. Principal component analysis was used to visualize the effects of the various additive treatments, and these data were also used to evaluate the best‐fitting regression models between AA and HMF with reducing sugar, asparagine, and color value (a*), and browning index. The resulting models showed a highly significant correlation (r &gt; 0.90, p &lt; 0.001). Organic acids and salts and pectin all significantly reduced the final AA content due to the change in pH. Additionally, amino acids decreased AA while maintaining the pH at its original value. With a combination of citric acid and l‐lysine, a synergistic AA‐lowering effect was observed.Practical applicationThis research will benefit the Indian food industry by demonstrating how an additive can be used as a pretreatment to compress the AA and HMF content of foods. This frequently raises the customer's awareness of consumable goods and the importance of determining the maximum amount that can be consumed daily to protect themselves from contaminants such as HMF and AA.

Inhibition of PPO-related browning in fresh noodles: A combination of chemical and heat treatment

Enzymatic browning has been a significant factor affecting the sale of fresh noodles. This study used a combination of physical and chemical methods to achieve a long-lasting and effective anti-browning effect in fresh noodles. The results showed that the combinations of citric acid (CA), NaOH, and KOH with heat treatment blunted the polyphenol oxidase activity and improved the color of fresh noodles. Specifically, the L* value of fresh noodles stored at 6 °C treated by the combination of CA and 75 °C (CHFN-75) at 72 h (81.71) was significantly higher than that of the control at 72 h (74.42). Mixolab and confocal laser scanning microscopy showed that the combined treatment affected the protein and starch of the flour. However, the hardness and chewiness of the cooked noodles increased only slightly, and the adhesiveness decreased slightly. The innovative combination can be used as an effective way to delay the darkening of fresh noodles.

PH-sensitive alginate hydrogel for synergistic anti-infection

This work designed a pH-sensitive sodium alginate hydrogel for combating bacterial infection caused by tissue damage. The antibacterial hydrogels were prepared using sodium alginate, citric acid, and vancomycin by one-step in situ method. Vancomycin (Van) was loaded into hydrogels via reversible imine bonds for controlled drug delivery. The morphology, swelling properties, and antibacterial activity of hydrogel were characterized. The hydrogel shown strong water absorbent behavior and pH-dependent performance. The result under weak acid conditions, the drug release rate of van-loaded gel was faster than neutral and alkaline conditions and followed zero-order kinetic release model, and the cumulative release amount could reach 86.7 % over 320 min. The van-loaded gel had highly effective antibacterial activity in a weak acid environment, the combination of citric acid and vancomycin had a synergistic therapeutic effect for acute infection. The drug-loaded hydrogel shows good biocompatibility. Compared with gauze, the drug-loaded hydrogel exhibited good coagulation properties, high platelet adhesion, high fluid absorption capacity, and proper balance of fluid on the wound bed. This work proposed this simple alginate-based drug delivery system has potential applications in the field of clinical treatment of infections.

A new injectable quick hardening anti-collapse bone cement allows for improving biodegradation and bone repair.

The development of injectable cement-like biomaterials via a minimally invasive approach has always attracted considerable clinical interest for modern bone regeneration and repair. Although α-tricalcium phosphate (α-TCP) powders may readily react with water to form hydraulic calcium-deficient hydroxyapatite (CDHA) cement, its long setting time, poor anti-collapse properties, and low biodegradability are suboptimal for a variety of clinical applications. This study aimed to develop new injectable α-TCP-based bone cements via strontium doping, α-calcium sulfate hemihydrate (CSH) addition and liquid phase optimization. A combination of citric acid and chitosan was identified to facilitate the injectable and anti-washout properties, enabling higher resistance to structure collapse. Furthermore, CSH addition (5%-15%) was favorable for shortening the setting time (5-20min) and maintaining the compressive strength (10-14MPa) during incubation in an aqueous buffer medium. These α-TCP-based composites could also accelerate the biodegradation rate and new bone regeneration in rabbit lateral femoral bone defect models in vivo. Our studies demonstrate that foreign ion doping, secondary phase addition and liquid medium optimization could synergistically improve the physicochemical properties and biological performance of α-TCP-based bone cements, which will be promising biomaterials for repairing bone defects in situations of trauma and diseased bone.