PBS Solution Research Articles

High-efficiency ammonia electrosynthesis on self-supported Co2AlO4 nanoarray in neutral media by selective reduction of nitrate

A Co2AlO4 nanosheet array on carbon cloth (Co2AlO4/CC) is proposed as a superb electrocatalyst for converting nitrate (NO3−) to ammonia (NH3). In 0.1 M PBS solution with 0.1 M NO3−, it attains an NH3 yield of 7.9 mg h−1 cm−2 with a Faradaic efficiency of 92.6%, with high durability. A Zn-NO3− battery with such Co2AlO4/CC as cathode offers a power density of 3.43 mW cm−2 with an NH3 yield of 750 μg h−1 cm−2. Theoretical calculations reveal that Al ions reduce the electron cloud density on the surface of Co, making it highly conducive to NO3− adsorption at Co sites. Additionally, Co2AlO4 (220) surface inhibits hydrogen evolution reaction but is highly active for NO3− reduction with a low energetically uphill pathway (ΔG of 0.42 eV) for the potential-determining step (*NO3 to *NO3H), much smaller than that of Co3O4 (220) (ΔG of 0.83 eV).

Nanomolar Nitric Oxide Concentrations in Living Cells Measured by Means of Fluorescence Correlation Spectroscopy.

Measurement of the nitric oxide (NO) concentration in living cells in the physiological nanomolar range is crucial in understanding NO biochemical functions, as well as in characterizing the efficiency and kinetics of NO delivery by NO-releasing drugs. Here, we show that fluorescence correlation spectroscopy (FCS) is perfectly suited for these purposes, due to its sensitivity, selectivity, and spatial resolution. Using the fluorescent indicators, diaminofluoresceins (DAFs), and FCS, we measured the NO concentrations in NO-producing living human primary endothelial cells, as well as NO delivery kinetics, by an external NO donor to the immortal human epithelial living cells. Due to the high spatial resolution of FCS, the NO concentration in different parts of the cells were also measured. The detection of nitric oxide by means of diaminofluoresceins is much more efficient and faster in living cells than in PBS solutions, even though the conversion to the fluorescent form is a multi-step reaction.

Synthesis of nanocapsules blended polymeric hydrogel loaded with bupivacaine drug delivery system for local anesthetics and pain management

Local anesthetics are used clinically for the control of postoperative pain management. This study aimed to develop chitosan (CS) with genipin (GP) hydrogels as the hydrophilic lipid shell loaded poly(ε-caprolactone) (PC) nanocapsules as the hydrophobic polymeric core composites (CS-GP/PC) to deliver bupivacaine (BPV) for the prolongation of anesthesia and pain relief. The swelling ratio, in vitro degradation, and rheological properties enhancement of CS-GP/PC polymeric hydrogel. The incorporation of PC nanocapsules into CS-GP hydrogels was confirmed by SEM, FTIR, and XRD analysis. Scanning electron microscopy results demonstrated that the CS-GP hydrogels and CS-GP/PC polymeric hydrogels have a porous structure, the pore dimensions being non-uniform with diameters between 25 and 300 μm. The in vitro drug release profile of CS-GP/PC polymeric hydrogel has been achieved 99.2 ± 1.12% of BPV drug release in 36 h. Cellular viability was evaluated using the CCK-8 test on 3T3 fibroblast cells revealed that the obtained CS-GP/PC polymeric hydrogel with BPV exhibited no obvious cytotoxicity. The CS-GP/PC polymeric hydrogel loaded with BPV showed significant improvement in pain response compared to the control group animals for at least 7 days. When compared with BPV solution, CS-GP hydrogel and CS-GP/PC polymeric hydrogel improved the skin permeation of BPV 3-fold and 5-fold in 24 h, respectively. In vitro and in vivo results pointed out PC nanocapsules loaded CS-GP hydrogel can act as effective drug carriers, thus prolonging and enhancing the anesthetic effect of BPV. Histopathological results demonstrated the excellent biodegradability and biocompatibility of the BPV-loaded CS-GP/PC polymeric hydrogel system on 7, 14, and 21 days without neurotoxicity. HIGHLIGHTS Preparation and characterization of CS-GP/PC polymeric hydrogel system. BPV-loaded CS-GP/PC exhibited prolonged in vitro release in PBS solution. Cytotoxicity of BPV-loaded CS-GP/PC polymeric hydrogel against fibroblast (3T3) cells. Development of CS-GP/PC a promising skin drug-delivery system for local anesthetic BPV.

Directional Growth of cm-Long PLGA Nanofibers by a Simple and Fast Wet-Processing Method.

The development of aligned nanofibers as useful scaffolds for tissue engineering is an actively sought-for research objective. Here, we propose a novel improvement of an existing self-assembly-based nanofabrication technique (ASB-SANS). This improvement, which we termed Directional ASB-SANS, allows one to produce cm2-large domains of highly aligned poly(lactic-co-glycolic acid) (PLGA) nanofibers in a rapid, inexpensive, and easy way. The so-grown aligned PLGA nanofibers exhibited remarkable adhesion to different substrates (glass, polyimide, and Si/SiOx), even when immersed in PBS solution and kept at physiological temperature (37 °C) for up to two weeks. Finally, the Directional ASB-SANS technique allowed us to grow PLGA fibers also on highly heterogeneous substrates such as polyimide-based, gold-coated flexible electrodes. These results suggest the viability of Directional ASB-SANS method for realizing biocompatible/bioresorbable, nanostructured coatings, potentially suitable for neural interface systems.

Preparation and Characterisation of Cellulose Nanocrystal/Alginate/Polyethylene Glycol Diacrylate (CNC/Alg/PEGDA) Hydrogel Using Double Network Crosslinking Technique for Bioprinting Application

In this study, we aimed to prepare and characterise hydrogel formulations using cellulose nanocrystals (CNCs), alginate (Alg), and polyethylene glycol diacrylate (PEGDA). The CNC/Alg/PEGDA formulations were formed using a double network crosslinking approach. Firstly, CNC was extracted from oil palm trunk, and the size and morphology of the CNCs were characterised using TEM analysis. Secondly, different formulations were prepared using CNCs, Alg, and PEGDA. The mixtures were crosslinked with Ca2+ ions and manually extruded using a syringe before being subjected to UV irradiation at 365 nm. The shear-thinning properties of the formulations were tested prior to any crosslinking, while the determination of storage and loss modulus was conducted post extrusion after the Ca2+ ion crosslink using a rheometer. For the analysis of swelling behaviour, the constructs treated with UV were immersed in PBS solution (pH 7.4) for 48 h. The morphology of the UV crosslinked construct was analysed using SEM imaging. The extracted CNC exhibited rod-like structures with an average diameter and length of around 7 ± 2.4 and 113 ± 20.7 nm, respectively. Almost all CNC/Alg/PEGDA formulations (pre-gel formulation) displayed shear-thinning behaviour with the power-law index η < 1, and the behaviour was more prominent in the 1% [w/v] Alg formulations. The CNC/Alg/PEGDA with 2.5% and 4% [w/v] Alg displayed a storage modulus dominance over loss modulus (G′ > G″) which suggests good shape fidelity. After the hydrogel constructs were subjected to UV treatment at 365 nm, only the F8 construct [4% CNC: 4% Alg: 40% PEGDA] demonstrated tough and flexible characteristics that possibly mimic the native articular cartilage property due to a similar water content percentage (79.5%). In addition, the small swelling ratio of 4.877 might contribute to a minimal change of the 3D construct’s geometry. The hydrogel revealed a rough and wavy surface, and the pore size ranged from 3 to 20 µm. Overall, the presence of CNCs in the double network hydrogel demonstrated importance and showed positive effects towards the fabrication of a potentially ideal 3D bioprinted scaffold.

Fabrication of water‐resistant, thermally stable, and antibacterial fibers through in situ multivalent crosslinking

AbstractFibers are emerging materials for biomedical applications, including drug delivery, sensing, tissue engineering, and wound dressing. However, fibers produced from water‐soluble polymers usually lose their morphology and quickly dissolve after exposure to water. Here, we developed a combined strategy of using multivalent crosslinkers along with in situ crosslinking to synthesize water‐resistant and thermally stable hybrid fibers. In our design, polyvinyl alcohol (PVA), aldehyde‐modified polyxylitol sebacate‐co‐polyethylene glycol (Ald_PXS‐co‐PEG, APP), and neomycin (Neo) were mixed to fabricate hybrid fibers through electrospinning. Several crosslinking chemistries were occurred in the hybrid fibers of PVA/APP/Neo, including the acetal bonds between PVA and APP, imine bonds between APP and Neo, and hydrogen bonds between PVA, APP, and Neo. These multiple chemical bonds allowed the PVA/APP/Neo fibers to maintain their fiber morphology after the immersion in the PBS solution, preserving the advantages of fibers (e.g., large surface‐to‐volume ratio and porosity) for applications in aqueous media. Particularly, the presence of Neo also provided the hybrid fibers with antimicrobial ability. Taken together, the in situ multivalent crosslinking has been demonstrated as a promising strategy to prepare stable and functional fibers for advanced applications.

Conception and Clinical Efficacy of an Osmotic, Polymeric, Stable Nasal Filmogen Barrier for Preventive Treatment of Allergen and Pollution Induced Rhinitis and Respiratory Symptoms

Background: Pollution induced allergic rhinitis and respiratory symptoms is becoming a major health problem in the world for which still there is no safe and preventive treatment. Objectives: Conceive and evaluate the allergen preventive properties and clinical efficacy of an osmotic, polymeric, stable filmogen spray, called PCNS. Materials and Methods: Amb A 1 (ragweed), Der P 1 and 2 (dust mite), Bet v 1 (birch), Alt a 1 (Alternaria, fungus), and Fel d 1 (cat dander) allergens were exposed at a concentration of 5µg/ml (20 µl per tube) on the polymeric test product film (120 and 240µl layer) and the allergens crossing the barrier were quantified in the agar gel beneath the film. 0.40% HPMC and PBS solutions, tested identically, served as controls. Clinical efficacy of PCNS nasal spray was evaluated in patients suffering from allergic rhinitis and/or respiratory symptoms (29 in test product v/s 15 in saline controls) for 22 days. Nasal, ocular, respiratory symptoms and Rhino conjunctivitis Quality of Life Questionnaire (RQLQ) were measured. Statistical analyses: The normality of the populations was determined by the Shapiro-Wilk test, then statistical analysis was performed by two-tailed Student’s test for comparisons between two groups and the two-way ANOVA followed by the post hoc Bonferroni’s test for comparisons of multiple groups. p<0.05 was considered statistically significant. The analyses were performed with the software GraphPad Prism (version 8.4.2, La Jolla, USA). NS indicates not significant. Results: PCNS polymeric spray blocked the diffusion of all the allergens while 0.40% HPMC was able to prevent diffusion of only Alt a 1 and Fel d 1 allergens. Mean reflective total nasal symptom scores (rTNSS), reflective total ocular symptom score (rTOSS), and respiratory symptoms including effect on wheezing, cough, dyspnea, and chest tightness were moderately improved in the control saline group, but the improvements were nearly twice better in the PCNS group. RQLQ was improved by 23% in saline spray v/s 46% PCNS group. 4/15 patients in saline group v/s 1/29 in PCNS group required rescue medication during the study. PCNS was highly effective in reducing allergen and pollution induced respiratory symptoms. Conclusion: a polymeric, osmotic, and stable nasal barrier against pollutants and allergens represents an innovative approach against pollution induced respiratory symptoms.

Mechanical Analysis and Corrosion Analysis of Zinc Alloys for Bioabsorbable Implants for Osteosynthesis.

Zinc alloys have recently been researched intensely for their great properties as bioabsorbable implants for osteosynthesis. Pure zinc (Zn) itself has relatively poor strength, which makes it insufficient for most clinical use. Research has already proven that the mechanical strength of zinc can be enhanced significantly by alloying it with silver. This study evaluated zinc silver alloys (ZnAg) as well as novel zinc silver titanium alloys (ZnAgTi) regarding their mechanical properties for the use as bioabsorbable implants. Compared to pure zinc the mechanical strength was enhanced significantly for all tested zinc alloys. The elastic properties were only enhanced significantly for the zinc silver alloys ZnAg6 and ZnAg9. Regarding target values for orthopedic implants proposed in literature, the best mechanical properties were measured for the ZnAg3Ti1 alloy with an ultimate tensile strength of 262 MPa and an elongation at fracture of 16%. Besides the mechanical properties, the corrosion rates are important for bioabsorbable implants. This study tested the corrosion rates of zinc alloys in PBS solution (phosphate buffered solution) with electrochemical corrosion measurement. Zinc and its alloys showed favorable corrosion rates, especially in comparison to magnesium, which has a much lower degradation rate and no buildup of hydrogen gas pockets during the process. Altogether, this makes zinc alloys highly favorable for use as material for bioabsorbable implants for osteosynthesis.

An efficient chemodosimeter for the detection of Hg(II) via diselenide oxidation.

Mercury ions are toxic and exhibit hazardous effects on the environment and biological systems, and thus demand for the selective and sensitive detection of mercury has become considerably an important issue. Here, we have developed a diselenide containing coumarin-based probe 3 for the selective detection of Hg(II) with a "turn-on" response (a 48 fold increase in fluorescence intensity) at 438 nm. The probe could quantitatively detect Hg(II) with a detection limit of 1.32 μM in PBS solution. Moreover, the probe has operable efficiency over the physiological range with an increase in the quantum yield from 1.2% to 57.3%. The reaction of the probe with Hg(II) yielded a novel monoselenide based coumarin 4via diselenide oxidation, which was confirmed by single crystal XRD. Furthermore, the biological use of the probe for the detection of Hg(II) was confirmed in the MCF-7 cell line. To the best of our knowledge, this is the first reaction-based probe for Hg(II) via diselenide oxidation.

Encapsulation of closo-dodecaiodododecaborate in 2-hydroxypropyl-γ-cyclodextrin prevents hemolysis.

Na2B12I12 has many of the properties desired by an X-ray contrast agent but is lethal at the concentrations needed for medical imaging. We demonstrate here that PBS solutions with >50 mM Na2B12I12 induce hemolysis, consistent with the previously reported superchaotropic nature of the anion. The presence of <1 equiv. of 2-hydroxypropyl-γ-cyclodextrin prevents hemolysis and suggests a strategy for exploiting B12I122- as an X-ray contrast agent.

RuO2 nanoparticle-decorated TiO2 nanobelt array as a highly efficient electrocatalyst for the hydrogen evolution reaction at all pH values

RuO2 nanoparticles decorated TiO2 nanobelt on titanium plate is active for electrocatalytic hydrogen evolution, requiring overpotentials of 130, 143, and 380 mV to drive 100 mA cm−2 in 0.5 M H2SO4, 1.0 M KOH, and 1.0 M PBS solution, respectively.

Fabrication of Antheraea pernyi Silk Fibroin-Based Thermoresponsive Hydrogel Nanofibers for Colon Cancer Cell Culture.

Antheraea pernyi silk fibroin (ASF)-based nanofibers have wide potential for biomaterial applications due to superior biocompatibility. It is not clear whether the ASF-based nanofibers scaffold can be used as an in vitro cancer cell culture platform. In the current study, we fabricated novel ASF-based thermoresponsive hydrogel nanofibers by aqueous electrospinning for colon cancer (LoVo) cells culture. ASF was reacted with allyl glycidyl ether (AGE) for the preparation of allyl silk fibroin (ASF-AGE), which provided the possibility of copolymerization with allyl monomer. The investigation of ASF-AGE structure by 1H NMR revealed that reactive allyl groups were successfully linked with ASF. ASF-based thermoresponsive hydrogel nanofibers (p (ASF-AGE-NIPAAm)) were successfully manufactured by aqueous electrospinning with the polymerization of ASF and N-isopropylacrylamide (NIPAAm). The p (ASF-AGE-NIPAAm) spinning solution showed good spinnability with the increase of polymerization time, and uniform nanofibers were formed at the polymerization time of 360 min. The obtained hydrogel nanofibers exhibited good thermoresponsive that the LCST was similar with PNIPAAm at about 32 °C, and good degradability in protease XIV PBS solution. In addition, the cytocompatibility of colon cancer (LoVo) cells cultured in hydrogel nanofibers was assessed. It was demonstrated that LoVo cells grown on hydrogel nanofibers showed improved cell adhesion, proliferation, and viability than those on hydrogel. The results suggest that the p (ASF-AGE-NIPAAm) hydrogel nanofibers have potential application in LoVo cells culture in vitro. This study demonstrates the feasibility of fabricating ASF-based nanofibers to culture LoVo cancer cells that can potentially be used as an in vitro cancer cell culture platform.

Study of Leukopenia Induced by a High Dose of Cyclophosphamide in Mice

Abstract: The study was conducted to evaluate the toxic effect of different concentrations of cyclophosphamide (CTX) by inducing leukopenia. Adult female Swiss albino mice weighting (20±4g) arranged in three groups of six animals each housed. A control mice saline PBS solution (group I), mice treated with 200 mg/Kg (4mg/mouse) cyclophosphamide, High dose (group II) and mice treated with treated 100 mg/kg (2mg/mouse) body weight Low dose (group III) for three weeks. Cyclophosphamide causes a significant decrease (P &lt; 0.01) in total leukocyte count (TLC), total erythrocyte count (TEC), and red blood cell distribution (RDW) in all groups compared to the control group of mice. Observed leukopenia inform marked reduced in the absolute numbers of lymphocytes, monocytes, and neutrophils in comparison to the control group of mice. The results indicate that cyclophosphamide alters the blood profile only after high doses while low doses had the least impact on blood pictures. Cyclophosphamide causes a significant increased (P &lt; 0.01) in activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum after CTX treatment with no effect on the serum albumin level compared to the control group. While lower doses had less effect on liver enzymes.

Electrochemical Behaviour of Ti and Ti-6Al-4V Alloy in Phosphate Buffered Saline Solution.

The electrochemical behavior of commercially pure titanium (CP Ti) and Ti-6Al-4V (Grade 5) alloy in phosphate buffered saline solution (PBS, pH = 7.4) at 37 °C (i.e., in simulated physiological solution in the human body) was examined using open circuit potential measurements, linear and potentiodynamic polarization and electrochemical impedance spectroscopy methods. After the impedance measurements and after potentiodynamic polarization measurements, the surface of the samples was investigated by scanning electron microscopy, while the elemental composition of oxide film on the surface of each sample was determined by EDS analysis. The electrochemical and corrosion behavior of CP Ti and Ti-6Al-4V alloys is due to forming a two-layer model of surface oxide film, consisting of a thin barrier-type inner layer and a porous outer layer. The inner barrier layer mainly prevents corrosion of CP Ti and Ti-6Al-4V alloy, whose thickness and resistance increase sharply in the first few days of exposure to PBS solution. With longer exposure times to the PBS solution, the structure of the barrier layer subsequently settles, and its resistance increases further. Compared to Ti-6Al-4V alloy, CP Ti shows greater corrosion stability.

Improved biotribological performance of Ti6Al4V alloy through the synergetic effects of porous TiO2 layer and zwitterionic hydrogel coating

To improve the biotribological properties of Ti6Al4V alloy for artificial joints, motivated by the composite structure of ‘natural articular cartilage - subchondral bone’ and the hydration lubrication mechanism of articular cartilage, a soft/hard bilayer coating composed of a porous TiO 2 layer and a zwitterionic hydrogel coating was designed and fabricated on Ti6Al4V alloy through micro-arc oxidation (MAO) combined with ultraviolet (UV) radiation technology. Characterization results revealed that the bio-inspired bilayer coating could be successfully constructed on Ti6Al4V alloy, and such a coating displayed good hydrophilicity (WCA: 32°). Notably, by ball - on - disk friction test, this biomimetic bilayer coating exhibited an ultra-low friction coefficient (∼0.038) in PBS solution, which was reduced by an order of magnitude compared with that of the Ti6Al4V alloy substrate. This was due to the synergistic effects of soft/hard composite structure and the hydration lubrication of zwitterionic MPC polymer. This work provides a novel and effective strategy for surface modification of Ti6Al4V alloy for artificial joints.

Comparison of the Morphological and Structural Characteristic of Bioresorbable and Biocompatible Hydroxyapatite-Loaded Biopolymer Composites.

Calcium phosphate (CaP)-based ceramic–biopolymer composites can be regarded as innovative bioresorbable coatings for load-bearing implants that can promote the osseointegration process. The carbonated hydroxyapatite (cHAp) phase is the most suitable CaP form, since it has the highest similarity to the mineral phase in human bones. In this paper, we investigated the effect of wet chemical preparation parameters on the formation of different CaP phases and compared their morphological and structural characteristics. The results revealed that the shape and crystallinity of CaP particles were strongly dependent on the post-treatment methods, such as heat or alkaline treatment of as-precipitated powders. In the next step, the optimised cHAp particles have been embedded into two types of biopolymers, such as polyvinyl pyrrolidone (PVP) and cellulose acetate (CA). The pure polymer fibres and the cHAp–biopolymer composites were produced using a novel electrospinning technique. The SEM images showed the differences between the morphology and network of CA and PVP fibres as well as proved the successful attachment of cHAp particles. In both cases, the fibres were partially covered with cHAp clusters. The SEM measurements on samples after one week of immersion in PBS solution evidenced the biodegradability of the cHAp–biopolymer composites.

Novel pH-responsive chitosan/sodium alginate/PEG based hydrogels for release of sodium ceftriaxone

pH-sensitive hydrogels have gained attraction in many biomedical fields. In this study, pH-sensitive hydrogels based on polyelectrolyte complex of chitosan/sodium alginate/PEG with 1,4-diaminobutane as a cross-linking agent were blended by solution casting method. FTIR was conducted to study the interactions among the polymer chains and crosslinker. The influence of the cross-linker concentration on the swelling behavior of the hydrogels was studied. SEM images exhibited the spongy hydrogel matrix and the drug entrapped in the hydrogel is also observed in drug loaded sample. TGA was conducted to check the effect of cross-linking density on the thermal stability of the hydrogel matrix. The release profile of sodium ceftriaxone (CTX) as a model drug in the solutions of PBS, SGF and SIF was investigated. In SGF, drug was released more than 10% in 30 min, while in PBS and SIF, the drug was released in a controlled manner. The comparison of UV spectra of pure and released drug confirmed its chemical stability in the developed hydrogels. The release profile according to the pharmacopeia standards designated the prepared hydrogels as a suitable candidate for drug release applications.

Near-infrared triggered injectable ferrimagnetic chitosan thermosensitive hydrogel for photo hyperthermia and precisely controlled drug release in tumor ablation

The combination of photothermal therapy (PTT) and chemotherapy has been a promising strategy for clinical cancer treatment, but traditional platforms using photothermal agents as drug carriers are poor at continuous fixation at the tumor site, often resulting in undesired thermal damage to surrounding healthy tissues and toxicity due to uncontrolled drug leakage. To provide an alternative strategy, an injectable ferrimagnetic chitosan thermosensitive hydrogel was developed in this study. The prepared hydrogel exhibited the gelation ability at 37℃ and long term stability in PBS solution. The firmly embedded photothermal agent iron oxide nanocubes (IONCs) endowed the chitosan hydrogel with excellent hyperthermia performance under near-infrared (NIR) triggering, and thus realized precisely responsive controlled release of loaded drugs. Compared with the pure photo hyperthermia and DOX therapies, ferrimagnetic chitosan hydrogel loaded with DOX showed synergistic effect and sustained treatment in tumor cells killing. Furthermore, the good biocompatibility of the hydrogel also ensured its application as a tumor ablation material.

Fully integrated flexible biosensor for wearable continuous glucose monitoring

Continuous physiological monitoring is a promising alternative to current chronic disease management for obtaining big data sets to help individualized therapy. Here, we present a continuous glucose monitoring platform consisting of a screen-printed electrochemical biosensor and a fully integrated wireless electrochemical analysis system. A biocompatible conjugated polymer (poly (N-phenylglycine)) was employed as the support material for enzyme immobilization. Specifically, a polyurethane outer layer was decorated onto the working electrode of the biosensor to construct a diffusion limiting membrane and improve the linear range of the glucose sensor. We optimized the fabricated glucose sensor so that it achieves a linear range of 1–30 mM and a sensitivity of 12.69 μA mM−1·cm−2 in vitro. The long-term stability is up to 30 days by storing in PBS solution at 4°C. The overall system design was very small (0.8 × 1.8 cm) and consisted of a signal conditioning part, a programmable electrochemical chip, and a wireless connection using Bluetooth Low Energy with a smartphone. Finally, we carried out biocompatibility tests and animal experiments to demonstrate the device can successfully monitor blood glucose in vivo.

Tailoring Competitive Adsorption Sites by Oxygen-Vacancy on Cobalt Oxides to Enhance the Electrooxidation of Biomass.

The electrooxidation of 5-hydroxymethylfurfural (HMF) offers a promising green route to attain high-value chemicals from biomass. The HMF electrooxidation reaction (HMFOR) is a complicated process involving the combined adsorption and coupling of organic molecules and OH- on the electrode surface. An in-depth understanding of these adsorption sites and reaction processes on electrocatalysts is fundamentally important. Herein, the adsorption behavior of HMF and OH- , and the role of oxygen vacancy on Co3 O4 are initially unraveled. Correspondingly, instead of the competitive adsorption of OH- and HMF on the metal sites, it is observed that the OH- can fill into oxygen vacancy (Vo) prior to couple with organic molecules through lattice oxygen oxidation reaction process, which could accelerate the rate-determining step of the dehydrogenation of 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) intermediates. With the modulated adsorption sites, the as-designed Vo-Co3 O4 shows excellent activity for HMFOR with the earlier potential of 90 and 120mV at 10mA cm-2 in 1 m KOH and 1 m PBS solution. This work sheds insight on the catalytic mechanism of oxygen vacancy, which benefits designing a novel electrocatalysts to modulate the multi-molecules combined adsorption behaviors.