Synthesis and comparison of the performance of two different water-soluble phthalocyanine based electrochemical biosensor.

Herein, a comparative study between novel water-soluble phthalocyanine-based biosensors was performed for the application of glucose sensing. For this purpose, two different copper (II) and manganese (III) phthalocyanines and their water-soluble derivatives were synthesized, and then their role as a supporting material for enzyme immobilization was evaluated by comparing their sensor performances. Two different phthalocyanine (AP-OH2-MnQ (MnPc) and AP-OH2-CuQ (CuPc)) were tested using electrochemical biosensor with immobilized glucose oxidase (GOx). To the best of our knowledge, the related water-soluble phthalocyanine-based glucose biosensors were attempted for the first time, and the developed approach resulted in improved biosensor characteristics. The constructed biosensors GE/MnPc/GOx and GE/CuPc/GOx showed good linearity between 0.003-1.0 mM and 0.05-0.4 mM, respectively. The limit of detection was estimated at 0.0026 mM for the GE/MnPc/GOx and 0.019 mM for the GE/CuPc/GOx. KMapp and sensitivity values were also calculated as 0.026 mM and 175.043 µAmM-1 cm-2 for the GE/MnPc/GOx biosensor and 0.178 mM and 117.478 µAmM-1 cm-2 for the GE/CuPc/GOx biosensor. Moreover, the fabricated biosensors were successfully tested to detect glucose levels in beverages with high recovery results. The present study shows that the proposed water-soluble phthalocyanines could be a good alternative for quick and cheap glucose sensing with improved analytical characteristics.

Multi-walled carbon nanotubes functionalized with a new Schiff base containing phenylboronic acid residues: application to the development of a bienzymatic glucose biosensor using a response surface methodology approach.

An innovative supramolecular architecture is reported for bienzymatic glucose biosensing based on the use of a nanohybrid made of multi-walled carbon nanotubes (MWCNTs) non-covalently functionalized with a Schiff base modified with two phenylboronic acid residues (SB-dBA) as platform for the site-specific immobilization of the glycoproteins glucose oxidase (GOx) and horseradish peroxidase (HRP). The analytical signal was obtained from amperometric experiments at - 0.050 V in the presence of 5.0 × 10-4 M hydroquinone as redox mediator. The concentration of GOx and HRP and the interaction time between the enzymes and the nanohybrid MWCNT-SB-dBA deposited at glassy carbon electrodes (GCEs) were optimized through a central composite design (CCD)/response surface methodology (RSM). The optimal concentrations of GOx and HRP were 3.0 mg mL-1 and 1.50 mg mL-1, respectively, while the optimum interaction time was 3.0 min. The bienzymatic biosensor presented a sensitivity of (24 ± 2) × 102 µA dL mg-1 ((44 ± 4) × 102 µA M-1), a linear range between 0.06 mg dL-1 and 21.6 mg dL-1 (3.1 µM-1.2 mM) (R2 = 0.9991), and detection and quantification limits of 0.02 mg dL-1 (1.0 µM) and 0.06 mg dL-1 (3.1 µM), respectively. The reproducibility for five sensors prepared with the same MWCNT-SB-dBA nanohybrid was 6.3%, while the reproducibility for sensors prepared with five different nanohybrids and five electrodes each was 7.9%. The GCE/MWCNT-SB-dBA/GOx-HRP was successfully used for the quantification of glucose in artificial human urine and commercial human serum samples.

Glucose Oxidase Coupling with Pistol-Like DNAzyme Based Colorimetric Assay for Sensitive Glucose Detection in Tears and Saliva.

Non-invasive monitoring of glucose levels in tears and saliva is crucial for diagnosing and predicting various illnesses, such as diabetic nephropathy. However, the capability of the current glucose detection methods to identify small amounts of glucose with a high sensitivity remains a significant obstacle. This study proposes a simple, visual technique for sensitively detecting glucose levels from tears and saliva using glucose oxidase (GOx) to catalyze glucose and pistol-like DNAzyme (PLDz) to enhance the signal. In particular, the ß-D-glucose present in the samples serves as the initial molecule that GOx identifies and catalyzes to generate gluconic acid and hydrogen peroxide (H2O2). The H2O2 induces the self-cleavage of PLDz, activating the "part b" sequence. This activation initiates catalytic hairpin assembly (CHA) and releases the DNAzyme section in the H1 probe. The DNAzyme acts as a peroxidase analog, facilitating the catalysis of the 3,3',5,5'-tetramethylbenzidine (TMB)-hydrogen peroxide (H2O2) system and resulting in color changes. The proposed method exhibits a broad detection range of six orders of magnitude and a low limit of 0.32 µM for glucose detection. Furthermore, the proposed method was highly effective in detecting glucose in saliva and tears, suggesting that it could potentially diagnose hyperglycemia-related disorders in clinical environments.

Glucose Oxidase-Coated Calcium Peroxide Nanoparticles as an Innovative Catalyst for In Situ H2O2-Releasing Hydrogels.

In situ forming and hydrogen peroxide (H2O2)-releasing hydrogels have been considered as attractive matrices for various biomedical applications. Particularly, horseradish peroxidase (HRP)-catalyzed crosslinking reaction serves efficient method to create in situ forming hydrogels due to its advantageous features, such as mild reaction conditions, rapid gelation rate, tunable mechanical strength, and excellent biocompatibility. Herein, a novel HRP-crosslinked hydrogel system is reported that can produce H2O2 in situ for long-term applications, using glucose oxidase-coated calcium peroxide nanoparticles (CaO2@GOx NPs). In this system, CaO2 gradually produced H2O2 to support the HRP-mediated hydrogelation, while GOx further catalyzed the oxidation of glucose for in situ H2O2 generation. As the hydrogel is formed rapidly is expected and the H2O2 release behavior is prolonged up to 10 days. Interestingly, hydrogels formed by HRP/CaO2@GOx-mediated crosslinking reaction provided a favorable 3D microenvironment to support the viability and proliferation of fibroblasts, compared to that of hydrogels formed by either HRP/H2O2 or HRP/CaO2/GOx-mediated crosslinking reaction. Furthermore, HRP/CaO2@GOx-crosslinked hydrogel enhanced the angiogenic activities of endothelial cells, which is demonstrated by the in vitro tube formation test and in ovo chicken chorioallantoic membrane model. Therefore, HRP/CaO2@GOx-catalyzed hydrogels is suggested as potential in situ H2O2-releasing materials for a wide range of biomedical applications.

Fe-doped biodegradable dendritic mesoporous silica nanoparticles for starvation therapy and photothermal-enhanced cascade catalysis in tumor therapy.

Combination therapies have attracted significant attention because they address the limitations of monotherapy while improving overall efficacy. In this study, we designed a novel nanoplatform, named GOx@Fe-DMSN@PDA (GFDP), by integrating Fe2+ into dendritic mesoporous silica nanoparticles (DMSN) and selecting glucose oxidase (GOx) as the model drug loaded into the DMSN pores. Additionally, we coated the surface of the DMSN with polydopamine (PDA) to confer pH/near infrared (NIR) light-responsive controlled-release behavior and photothermal therapy (PTT). The introduction of Fe2+ into the DMSN framework greatly improved biodegradability and enhanced the peroxidase (POD)-like activity of GFDP. In addition, GOx could consume glucose and generate hydrogen peroxide (H2O2) within tumor cells to facilitate starvation therapy and enhance cascade catalysis. The PDA coating provided the DMSN with an intelligent response release ability, promoting efficient photothermal conversion and achieving the PTT effect. Cellular tests showed that under NIR light irradiation, GFDP exhibited a synergistic effect of PTT-enhanced starvation therapy and cascade catalysis, with a half-maximal inhibitory concentration (IC50) of 2.89 µg/mL, which was significantly lower than that of GFDP without NIR light irradiation (18.29 µg/mL). The in vivo anti-tumor effect indicated that GFDP could effectively accumulate at the tumor site for thermal imaging and showed remarkable synergistic therapeutic effects. In summary, GFDP is a promising nanoplatform for multi-modal combination therapy that integrates starvation therapy, PTT, and cascade catalysis.

Dual-mode detection of glucose based on pistol-like DNAzyme-mediated exonuclease-assisted signal cycle.

Detecting glucose accurately and sensitively from clinical samples like tears and saliva is still difficult. We have created a sensor that can detect glucose with high sensitivity and accuracy by combining the use of glucose oxidase (GOx) to catalyze glucose, a pistol-like DNAzyme (PLDz) to transform the signal, gold nanoparticles (AuNPs) to enhance the optical properties and the exonuclease-III (Exo-III) to amplify the signal. As a result, the proposed method exhibits a low detection limit of 7.5 pM and a wide detection range covering seven orders of magnitude. The suggested dual-mode strategy provides a sensitive, precise and specific detection method for glucose. Another advantage is that the dual-mode technique significantly improves the precision and consistency of the measurements, demonstrating its immense potential for use in biomedical research and clinical diagnostics.

[Box: see text].

Designing Mesoporous Prussian Blue@zinc Phosphate Nanoparticles with Hierarchical Pores for Varisized Guest Delivery and Photothermally-Augmented Chemo-Starvation Therapy.

Background: With the rapid development of nanotechnology, constructing a multifunctional nanoplatform that can deliver various therapeutic agents in different departments and respond to endogenous/exogenous stimuli for multimodal synergistic cancer therapy remains a major challenge to address the inherent limitations of chemotherapy. Methods: Herein, we synthesized hollow mesoporous Prussian Blue@zinc phosphate nanoparticles to load glucose oxidase (GOx) and DOX (designed as HMPB-GOx@ZnP-DOX NPs) in the non-identical pore structures of their HMPB core and ZnP shell, respectively, for photothermally augmented chemo-starvation therapy. Results: The ZnP shell coated on the HMPB core, in addition to providing space to load DOX for chemotherapy, could also serve as a gatekeeper to protect GOx from premature leakage and inactivation before reaching the tumor site because of its degradation characteristics under mild acidic conditions. Moreover, the loaded GOx can initiate starvation therapy by catalyzing glucose oxidation while causing an upgradation of acidity and H2O2 levels, which can also be used as forceful endogenous stimuli to trigger smart delivery systems for therapeutic applications. The decrease in pH can improve the pH-sensitivity of drug release, and O2 can be supplied by decomposing H2O2 through the catalase-like activity of HMPBs, which is beneficial for relieving the adverse conditions of anti-tumor activity. In addition, the inner HMPB also acts as a photothermal agent for photothermal therapy and the generated hyperthermia upon laser irradiation can serve as an external stimulus to further promote drug release and enzymatic activities of GOx, thereby enabling a synergetic photothermally enhanced chemo-starvation therapy effect. Importantly, these results indicate that HMPB-GOx@ZnP-DOX NPs can effectively inhibit tumor growth by 80.31% and exhibit no obvious systemic toxicity in mice. Conclusion: HMPB-GOx@ZnP-DOX NPs can be employed as potential theranostic agents that incorporate multiple therapeutic modes to efficiently inhibit tumors.

Gas Cluster Ion Beam-Assisted Deposition for Fabricating Dry Multilayers Containing Enzyme and Substrate with On-Demand Release.

Gas cluster ion beam (GCIB)-assisted deposition is used to build multilayered protein-based structures. In this process, Ar3000-5000+ clusters bombard and sputter molecules from a reservoir (target) to a collector, an operation that can be sequentially repeated with multiple targets. The process occurs under a vacuum, making it adequate for further sample conservation in the dry state, since many proteins do not have long-term storage stability in the aqueous state. First of all, the stability in time and versatility in terms of molecule selection are demonstrated with the fabrication of peptide multilayers featuring a clear separation. Then, lysozyme and trypsin are used as protein models to show that the activity remaining on the collector after deposition is linearly proportional to the argon ion dose. The energy per atom (E/n) of the Ar clusters is a parameter that was also changed for lysozyme deposition, and its increase negatively affects activity. The intact detection of larger protein molecules by SDS-PAGE gel electrophoresis and a bioassay (trypsin at ≈25 kDa and glucose oxidase (GOx) at ≈80 kDa) is demonstrated. Finally, GOx and horseradish peroxidase, two proteins involved in the same enzymatic cascade, are successively deposited on ß-d-glucose to build an on-demand release material in which the enzymes and the substrate (ß-d-glucose) are combined in a dry trilayer, and the reaction occurs only upon reintroduction in aqueous medium.

Self-activated hydrogel cascade reactor integrated with glucose oxidase and silver nanoparticle for enhanced treatment of bacterial infection.

The recognition of silver nanoparticles (AgNPs) as a nanozyme with peroxidase-like activity has offered a promising solution to address the challenges of bacterial resistance and argyria risk. However, the catalytic efficacy of AgNPs is limited by the need for a strong acidic environment and high concentrations of hydrogen peroxide (H2O2). In this work, we developed a self-activated hydrogel cascade reactor (AUGP) for enhanced treatment of bacterial infection. The AUGP integrates the properties of glucose oxidase (GOx) and polyacrylamide (pAAm) hydrogel microsphere. The confinement effect of pAAm hydrogel microsphere enables glucose oxidation to occur in a confined space, which creates an acidic environment to activate AgNPs activity, initiating the cascade reaction between GOx and AgNPs. Meanwhile, the confinement effect facilitates the accumulation of a high local concentration of H2O2, allowing AUGP to generate hydroxyl radicals (•OH) without the need for external H2O2. Additionally, the release of Ag+ from AUGP is achieved upon the generation of •OH. The synergistic action of Ag+ and •OH confers exceptional antibacterial efficacy to AUGP. Importantly, the etching effect of H2O2 ensures the absence of any residual AgNPs, reducing the risk of argyria. In vivo studies validated the efficacy of AUGP in wound disinfection with minimal toxicity.

Spodoptera frugiperda Salivary Glucose Oxidase Reduces the Release of Green Leaf Volatiles and Increases Terpene Emission from Maize.

The intricate relationships between plants and insects are essential for understanding ecological dynamics. Among these interactions, HIPVs serve as a pivotal defense mechanism. Our findings reveal the highly conserved nature of the GOX gene within the Lepidoptera order, highly expressed in the salivary glands of S. frugiperda, and its role in mediating maize's defense responses. Notably, salivary GOX activity expression significantly decreases subsequent gene knockout. The presence of GOX in the saliva of S. frugiperda significantly modulates the emission of HIPVs during maize consumption. This research delineates that GOX selectively inhibits the emission of certain green leaf volatiles (GLVs) while concurrently enhancing the release of terpene volatiles. This study unveils a novel mechanism whereby S. frugiperda utilizes GOX proteins in OS to modulate volatile emissions from maize, offering fresh perspectives on the adaptive evolution of phytophagous insects and their interactions with their preferred host plants.

In-Situ Generation of Hydrogen Polysulfides (H2Sn) with Thioglucose, Glucose Oxidase, and Chloroperoxidase.

Hydrogen polysulfides (H2Sn) have emerged as critical physiological mediators that are closely associated with hydrogen sulfide (H2S) signaling. H2Sn exhibit greater nucleophilicity than H2S while also having electrophilic characteristics, enabling unique activities such as protein S-persulfidation. Despite their physiological importance, mechanisms and reactivities of H2Sn remain inadequately explored due to their inherent instability in aqueous environments. Consequently, there is a need to develop biocompatible methods for controlled H2Sn generation to elucidate their behaviors in biological contexts. Herein, we present a dual enzyme system (containing glucose oxidase (GOx) and chloroperoxidase (CPO)) with thioglucose as the substrate to facilitate the controlled release of H2Sn. Fluorescence measurements with SSP4 and the trapping studies allowed us to confirm the production of H2Sn. Such a method may be useful in elucidating the reactivity of hydrogen polysulfides in biological systems as well as provide a potential delivery of H2Sn to target sites for biological applications.

Hydrogen peroxide and glucose detection using surface plasmon resonance imaging biosensor with corrodible silver thin film.

A surface plasmon resonance imaging (SPRI)-based biosensor is demonstrated for the detection of both hydrogen peroxide (H2O2) and glucose. The H2O2 to be detected acts as an oxidant and etch the silver film. This process gradually effects on resonance condition and consequently the reflected light intensity at a fixed angle. The etching rate of the silver film shows a clear relation with the H2O2 concentration. Therefore, monitoring the reflected light intensity progressively changing over a few minutes, enables accurate detection of H2O2 concentrations ranging from 0 to 200 µM (within physiological range of 0.25-50 µM), with a remarkable limit of detection (LOD) as low as 40 nM. In this regard, the behavior of the surface plasmon resonance (SPR) dip in response to the reduction of the silver film thickness is predicted by Winspall simulation software. These simulation results are in good agreement with the experimental results. Moreover, the proposed method can be applied to determine glucose concentrations ranging from 0 to 10 mM, encompassing the physiological range of 3-8 mM. This is achieved by observing the generated H2O2 through the enzymatic oxidation reaction between glucose and glucose oxidase (Gox). The sensor demonstrates remarkable sensitivity and selectivity, with a detection limit as low as 175 µM for glucose concentration. Furthermore, accurate measurement of glucose concentration in an actual human serum sample is achievable with the proposed sensor, using the standard addition method. The suggested glucose sensor shows promising prospects for use in routine glucose testing, employing a label-free, real-time, and multiplex detection approach.© 2017 Elsevier Inc. All rights reserved.

Determination of glucose oxidase activity by tyrosine fluorescence spectrophotometry.

A novel Fe2+/Tyr/H2O2 fluorescence reaction system has been established for the purpose of analyzing glucose oxidase activity. This system involves the catalysis of glucose oxidase on glucose to produce H2O2, which in turn oxidizes tyrosine to a highly fluorescent substance under the catalysis of Fe2+. The fluorescence intensity is subsequently employed to ascertain the enzymatic activity of glucose oxidase. The enzymatic oxidation reaction and tyrosine fluorescence reaction conditions were optimized based on the H2O2 standard curve equation. Direct fluorescence spectrophotometry was used to determine the activity range and detection limit of glucose oxidase, which were found to be 7.00 × 10-5-7.00 × 10-2 U/mL and 3.36 × 10-5 U/mL (Enzyme-like activity is 6.72 × 10-4 U/mL, The enzyme reaction time is 5 min), respectively, with a relative standard deviation of less than 3.2 %. This method has been successfully applied to determine the activity of glucose oxidase in food additives, with a recovery rate ranging from 96.00 % to 102.0 %.

Investigation of Direct Electron Transfer of Glucose Oxidase on a Graphene-CNT Composite Surface: A Molecular Dynamics Study Based on Electrochemical Experiments.

Graphene and its variants exhibit excellent electrical properties for the construction of enzymatic interfaces. In particular, the direct electron transfer of glucose oxidase on the electrode surface is a very important issue in the development of enzyme-based bioelectrodes. However, the number of studies conducted to assess how pristine graphene forms different interfaces with other carbon materials is insufficient. Enzyme-based electrodes (formed using carbon materials) have been extensively applied because of their low manufacturing costs and easy production techniques. In this study, the characteristics of a single-walled carbon nanotube/graphene-combined enzyme interface are analyzed at the atomic level using molecular dynamics simulations. The morphology of the enzyme was visualized using an elastic network model by performing normal-mode analysis based on electrochemical and microscopic experiments. Single-carbon electrodes exhibited poorer electrical characteristics than those prepared as composites with enzymes. Furthermore, the composite interface exhibited 4.61- and 2.45-fold higher direct electron efficiencies than GOx synthesized with single-carbon nanotubes and graphene, respectively. Based on this study, we propose that pristine graphene has the potential to develop glucose oxidase interfaces and carbon-nanotube-graphene composites for easy fabrication, low cost, and efficient electrode structures for enzyme-based biofuel cells.

Development of cross-linked glucose oxidase integrated Cu-nanoflower electrode for reusable and stable glucose sensing.

The demand for glucose-sensing devices has increased along with the increasing diabetic population. Here, we aimed to construct a system with a glucose oxidase (GOx)-integrated Cu-nanoflower (Cu-NF) as the underlying electrode. This novel system was successfully developed by creating a cross-linked GOx within a Cu-NF matrix, forming a c-GOx@Cu-NF-coated film on a carbon screen-printed electrode (CSPE). A comparison of the stabilities of the cross-linking methods demonstrated enhanced durability, with an activity level of >88 % maintained after approximately 35 days of storage in room temperature buffer. Regarding the ability of the c-GOx@Cu-NF modified CSPE to detect glucose via electrochemical methods, the redox potential gap (ΔE) and peak current increased in the presence of GOx. In comparison to that of glucose, the sensitivity of c-GOx@Cu-NF was approximately 8 times greater than that of GOx@Cu-NF, with a detection limit of 0.649 µM and a linear range of 5-500 µM. It sustained an average relative activity of 80 % over 20 days. After 10 cycles of repeated use, the activity remained above 75 %. In terms of evaluating the electrode's specificity for glucose, the detection rate for individual similar substances was approximately 1 %. The introduction of a crosslinking strategy to Cu-NF, leading to enhanced mechanical stability and conductivity, improved the detection capability. Furthermore, this approach led to increased long-term storage stability and reusability, allowing for specific glucose detection. To our knowledge, this report represents the first demonstration of a c-GOx@Cu-NF system for integrating electrochemical biosensing devices into digital healthcare pathways, offering enhanced sensing accuracy and mechanical stability.

Oxalic Acid Treatment: Short-Term Effects on Enzyme Activities, Vitellogenin Content, and Residual Oxalic Acid Content in House Bees, Apis mellifera L.

Honeybees (Apis mellifera L.) have to face many challenges, including Varroa destructor infestation, associated with viral transmission. Oxalic acid is one of the most common treatments against Varroa. Little is known about the physiological effects of oxalic acid, especially those on honeybees' immune systems. In this study, the short-term effects (0-96 h) of oxalic acid treatment on the immune system components (i.e., glucose oxidase, phenoloxidase, glutathione S-transferase, catalase activities, and vitellogenin contents) of house bees were preliminarily investigated. Oxalic acid contents of bee bodies and haemolymphs were also measured. The results confirm that oxalic acid is constitutively present in bee haemolymphs and its concentration is not affected by treatment. At 6 h after the treatment, a maximum peak of oxalic acid content was detected on bees' bodies, which gradually decreased after that until physiological levels were reached at 48 h. In the immune system, the oxalic acid treatment determined a peak in glucose oxidase activity at 48 h, indicating a potential defence response and an increase in vitellogenin content at 24 h. No significant changes were recorded in phenoloxidase, glutathione S-transferase, and catalase activities. These results suggest a time-dependent response to oxalic acid, with potential immune system activation in treated bees.

Blocking the utilization of carbon sources via two pathways to induce tumor starvation for cancer treatment.

Glucose oxidase (GOx) is often used to starvation therapy. However, only consuming glucose cannot completely block the energy metabolism of tumor cells. Lactate can support tumor cell survival in the absence of glucose. Here, we constructed a nanoplatform (Met@HMnO2-GOx/HA) that can deplete glucose while inhibiting the compensatory use of lactate by cells to enhance the effect of tumor starvation therapy. GOx can catalyze glucose into gluconic acid and H2O2, and then HMnO2 catalyzes H2O2 into O2 to compensate for the oxygen consumed by GOx, allowing the reaction to proceed sustainably. Furthermore, metformin (Met) can inhibit the conversion of lactate to pyruvate in a redox-dependent manner and reduce the utilization of lactate by tumor cells. Met@HMnO2-GOx/HA nanoparticles maximize the efficacy of tumor starvation therapy by simultaneously inhibiting cellular utilization of two carbon sources. Therefore, this platform is expected to provide new strategies for tumor treatment.

Au nanozyme-based colorimetric sensor array integrates machine learning to identify and discriminate monosaccharides.

As different monosaccharides exhibit different redox characteristics, this paper presented a novel colorimetric sensor array based on the glucose oxidase-like (GOx-like) activity of Au nanoparticles (NPs) for monosaccharides identification. AuNPs can use O2, ABTS+•, or [Ag(NH3)2]+ as an electron acceptor to catalyze the oxidation of monosaccharides in different velocity, resulting in cross-responsive signals. The current sensor array can distinguish between different monosaccharides or their mixtures through linear discriminant analysis (LDA) and hierarchical clustering analysis (HCA). Moreover, the glucose and fructose concentrations can be estimated simultaneously using a neural network regression model based on the sensor array. This method shows potential for monosaccharide detection in industrial, medical, and biological applications.

A Glucose Oxidase-Curcumin Composite Nanoreactor for Multimodal Synergistic Cancer Therapy.

Glucose oxidase (GOx) selectively oxidizes ß-d-glucose into gluconic acid and hydrogen peroxide; thus, it has emerged as a promising anticancer agent by tumor starvation and oxidative therapy. Here, we developed a nanoscale platform or "nanoreactor" that incorporates GOx and the bioactive natural product curcumin (CUR) to achieve a multimodal anticancer nanocomposite. The composite nanoreactor was formed by loading CUR in biodegradable polymeric nanoparticles (NPs) of poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-PCL). Prime-coating of the NPs with an iron(III)-tannic acid complex enabled facile immobilization of GOx on the NP surface. The NPs were monodisperse with a hydrodynamic diameter of 122 nm and a partially negative surface charge. The NPs were also associated with an excellent CUR loading efficiency and sustained release up to 96 h, which was accelerated by surface-immobilized GOx and followed supercase II transport. Viability assays were conducted on two model cancer cell lines, MCF-7 and MDA-MB-231 cells, as well as human dermal fibroblasts as a representative normal cell line. The assays revealed significantly improved potency of CUR in the composite nanoreactor, with up to 6000- and 1280-fold increase in MCF-7 and MDA-MB-231 cells, respectively, and lower toxicity toward normal cells. The NPs were also able to promote intracellular reactive oxygen species (ROS) generation and dissipation of the mitochondrial membrane potential, providing important clues on the mechanism of action of the nanoreactor. Further investigation of caspase-3 activity revealed that the nanoreactor had no effect or inhibited caspase-3 levels, signifying a caspase-independent mechanism of inducing apoptosis. Our findings present a promising nanocarrier platform that combines therapeutic agents with distinct mechanisms of action acting in synergy for more effective cancer therapy.

The influence of near-infrared carbon dots on the conformational variation and enzymatic activity of glucose oxidase: A multi-spectroscopic and biochemical study with molecular docking.

In recent years, the exceptional biocatalytic properties of glucose oxidase (GOx) have spurred the development of various GOx-functionalized nanocatalysts for cancer diagnosis and treatment. Carbon dots, renowned for their excellent biocompatibility and distinctive fluorescence properties, effectively incorporate GOx. Given the paramount importance of GOx's enzymatic activity in therapeutic efficacy, this study conducts a thorough exploration of the molecular-level binding dynamics between GOx and near-infrared carbon dots (NIR-CDs). Utilizing various spectrometric and molecular simulation techniques, we reveal that NIR-CDs form a ground-state complex with GOx primarily via hydrogen bonds and van der Waals forces, interacting directly with amino acid residues in GOx's active site. This binding leads to conformational change and reduces thermal stability of GOx, slightly inhibiting its enzymatic activity and demonstrating a competitive inhibition effect. In vitro experiments demonstrate that NIR-CDs attenuate the GOx's capacity to produce H2O2 in HeLa cells, mitigating enzyme-induced cytotoxicity and cellular damage. This comprehensive elucidation of the intricate binding mechanisms between NIR-CDs and GOx provides critical insights for the design of NIR-CD-based nanotherapeutic platforms to augment cancer therapy. Such advancements lay the groundwork for innovative and efficacious cancer treatment strategies.