Fibrinogen Solution Research Articles

Impact of Temperature on the Self-Assembly of Fibrinogen in Thrombin-Free Solutions.

Self-assembly of thrombin-free solutions of fibrinogen can be triggered not only by a drop in the ionic strength but also by an appropriate decrease in temperature. Accordingly, an in situ study of self-assembly of fibrinogen in saline buffered solution is carried out by means of time-resolved light scattering providing the molar mass, geometric size, and hydrodynamic radius of the growing intermediates. The resulting data provide access to the morphology of the intermediates and to the mechanism in which these intermediates grow during the early stages of self-assembly. Modeling the results of concentration dependent experiments based on temperature gradients in terms of a chain growth mechanism leads to the corresponding molar standard enthalpy and entropy of aggregation.

A Fibrin-Thrombin Based In Vitro Perfusion System to Study Flow-Related Prosthetic Heart Valves Thrombosis

Prosthetic heart valve (PHV) replacement has increased the survival rate and quality of life for heart valve-diseased patients. However, PHV thrombosis remains a critical problem associated with these procedures. To better understand the PHV flow-related thrombosis problem, appropriate experimental models need to be developed. In this study, we present an in vitro fibrin clot model that mimics clot accumulation in PHVs under relevant hydrodynamic conditions while allowing real-time imaging. We created 3D-printed mechanical aortic valve models that were inserted into a transparent glass aorta model and connected to a system that simulates human aortic flow pulse and pressures. Thrombin was gradually injected into a circulating fibrinogen solution to induce fibrin clot formation, and clot accumulation was quantified via image analysis. The results of valves positioned in a normal versus a tilted configuration showed that clot accumulation correlated with the local flow features and was mainly present in areas of low shear and high residence time, where recirculating flows are dominant, as supported by computational fluid dynamic simulations. Overall, our work suggests that the developed method may provide data on flow-related clot accumulation in PHVs and may contribute to exploring new approaches and valve designs to reduce valve thrombosis.

In situ injectable hydrogel encapsulating Mn/NO-based immune nano-activator for prevention of postoperative tumor recurrence

Postoperative tumor recurrence remains a predominant cause of treatment failure. In this study, we developed an in situ injectable hydrogel, termed MPB-NO@DOX + ATRA gel, which was locally formed within the tumor resection cavity. The MPB-NO@DOX + ATRA gel was fabricated by mixing a thrombin solution, a fibrinogen solution containing all-trans retinoic acid (ATRA), and a Mn/NO-based immune nano-activator termed MPB-NO@DOX. ATRA promoted the differentiation of cancer stem cells, inhibited cancer cell migration, and affected the polarization of tumor-associated macrophages. The outer MnO2 shell disintegrated due to its reaction with glutathione and hydrogen peroxide in the cytoplasm to release Mn2+ and produce O2, resulting in the release of doxorubicin (DOX). The released DOX entered the nucleus and destroyed DNA, and the fragmented DNA cooperated with Mn2+ to activate the cGAS-STING pathway and stimulate an anti-tumor immune response. In addition, when MPB-NO@DOX was exposed to 808 nm laser irradiation, the Fe-NO bond was broken to release NO, which downregulated the expression of PD-L1 on the surface of tumor cells and reversed the immunosuppressive tumor microenvironment. In conclusion, the MPB-NO@DOX + ATRA gel exhibited excellent anti-tumor efficacy. The results of this study demonstrated the great potential of in situ injectable hydrogels in preventing postoperative tumor recurrence.

Biomechanics, Energetics, and Structural Basis of Rupture of Fibrin Networks.

Fibrin provides the main structural integrity and mechanical strength to blood clots. Failure of fibrin clots can result in life-threating complications, such as stroke or pulmonary embolism. The dependence of rupture resistance of fibrin networks (uncracked and cracked) on fibrin(ogen) concentrations in the (patho)physiological 1-5gL-1 range is explored by performing the ultrastructural studies and theoretical analysis of the experimental stress-strain profiles available from mechanical tensile loading assays. Fibrin fibers in the uncracked network stretched evenly, whereas, in the cracked network, fibers around the crack tip showed greater deformation. Unlike fibrin fibers in cracked networks formed at the lower 1-2.7gL-1 fibrinogen concentrations, fibers formed at the higher 2.7-5gL-1 concentrations align and stretch simultaneously. Cracked fibrin networks formed in higher fibrinogen solutions are tougher yet less extensible. Statistical modeling revealed that the characteristic strain for fiber alignment, crack size, and fracture toughness of fibrin networks control their rupture resistance. The results obtained provide a structural and biomechanical basis to quantitatively understand the material properties of blood plasma clots and to illuminate the mechanisms of their rupture.

Methacrylated fibrinogen hydrogels for 3D cell culture and delivery.

Methacrylation was performed on fibrinogen to design a new biomedical hydrogel for 3D cell culture or as a biodegradable delivery matrix for in vivo implantation. The methacrylation of denatured fibrinogen in solution was performed using methacrylic anhydride (MAA). The extent of fibrinogen methacrylation was quantified by proton NMR and controlled using stochiometric quantities of MAA during the reaction. The methacrylated fibrinogen (FibMA) hydrogels were formed by light-activated free-radical polymerization in the presence of macromolecular cross-linking polymers made from acrylated poly(ethylene glycol) (PEG). The biocompatibility and biodegradability of the FibMA hydrogels were characterized by in vitro assays and in vivo implantation experiments using quantitative magnetic resonance imaging (MRI) of the implant volume. The FibMA supported the growth and metabolic activity of human dermal fibroblasts in both 2D and 3D cultures. The methacrylation did not alter important biological attributes of the fibrinogen, including the ability to support cell adhesion and 3D cell culture, as well as to undergo proteolysis. Animal experiments confirmed the biodegradability of the FibMA for potential use as a scaffold in tissue engineering, as a bioink for 3D bioprinting, or as a biodegradable matrix for in vivo sustained delivery of bioactive factors. STATEMENT OF SIGNIFICANCE: This paper describes methacrylated fibrinogen (FibMA) and the formation of a biomedical hydrogel from FibMA for cell culture and other biomedical applications. Inspired from methacrylated gelatin (GelMA), the FibMA is made from blood-derived fibrinogen which is more suitable for clinical use. Sharing similar properties to other hydrogels made from methacrylated proteins, the FibMA has yet to be reported in the literature. In this manuscript, we provide the methodology to produce the FibMA hydrogels, we document the mechanical versatility of this new biomaterial, and we show the biocompatibility using 3D cell culture studies and in vivo implantations.

An Investigation on the Fibrin Glue's Impact on Myringoplasty's Success Rate: A Randomized Controlled Study

Objective: The study's goal is to evaluate the success rates of graft uptake in platelet-rich fibrin-assisted underlay myringoplasties employing temporalis fascia grafts to those in traditional underlay myringoplasties. Methods: This study was conducted in Mayo Hospital in Lahore's ENT department carried out this double-blind, randomized, controlled trial investigation. We recruited 60 individuals with dry central tympanic membrane perforations. Patients with co-morbidities such as diabetes and sensorineural hearing loss were not included. Probability basic random sampling was used. The patients were split into two groups using a lottery system. With the help of SPSS version 26, statistical analysis was carried out. The P-value was calculated using the chi-square test. Results: There were 60 patients, of whom 38 were males and 22 were women. The control group's average age was 27.53 ± 11.41 years, but the study group's average age (Fibrin) was 31.77 ± 12.43 years. At the 2-month follow-up, the grafts were successfully absorbed by every patient in the platelet-rich fibrin group. 23 out of 30 patients in the control group who underwent the conventional method successfully absorbed their grafts, however, the remaining 7 patients had different issues that led to graft rejection. Practical Implication: The tympanic membrane would mend more quickly if platelet-rich fibrin was used after ear procedures. Fibrin glue in tympanoplasty has been tried in several locations throughout the globe. [7,8] When concentrated fibrinogen solutions are combined with thrombin, fibrin glue is created. It may also be made from platelet-rich plasma. Our research compares platelet-rich fibrin-assisted underlay myringoplasties employing temporalis fascia grafts to traditional underlay myringoplasties to see which has a higher graft uptake success rate. Conclusions: The use of platelet-rich fibrin on the anterior ligament grafting line and perforation edges during underlay myringoplasty has greatly increased the success rate of the graft. Keywords: platelet-rich fibrin, temporal fascia graft, myringoplasty

DYNAMIC SURFACE PROPERTIES OF FIBRIN

Fibrin is formed via polymerization of one of the main blood proteins, fibrinogen, under the action of an enzyme, thrombin. Dynamic surface elasticity and dynamic surface tension of mixed solutions of fibrinogen and thrombin are measured as functions of surface age and enzyme concentration (50–800 U/L). The nonmonotonic pattern of the dependences for the dynamic surface elasticity indicates the multistage character of fibrin film formation and makes it possible to monitor the transition from unfolded protein to individual filamentous aggregates; a network of branched fibrils; and, finally, a continuous film. The dynamic surface elasticity of fibrin films is twofold higher than the corresponding values for fibrinogen (115 and 55 mN/m, respectively). The use of different types of microscopy makes it possible to assess the morphology of the obtained films.

ACTION OF VENOM OF VIPERA LEBETINA ON BLOOD COAGULATION in vitro

Aim. In this study we focused on the search of fibrinogen-targeted proteases in the venom of Vipera lebetina. Methods. Fractionation of the venom was performed using FPLC chromatographic system Acta Prime on Q Sepharose. Analysis of protein mixtures was performed using SDS-PAGE. Аction on blood coagulation system was analyzed using APTT assay [2]. Proteolytic action on fibrinogen and identification of protein components with fibrinolytic activity was performed using electrophoresis of mixture of fibrinogen solution (2 mg/ml) with venom`s fractions. For a comprehensive evaluation of the effect of the obtained fractions on hemostasis, an original approach with modified aggregatometry was used [3]. This approach made it possible to take into account the ability of fractions to activate platelets, initiate blood coagulation, or inhibit platelet aggregation. Hemolytic action of fractions was estimated using fresh human red cells. Amount of released hemoglobin was estimated by spectrophotometry on Optizen POP. Results. Crude venom of V. lebetina was fractionated using ion-exchange chromatography on Q Sepharose. Elution was performed using a stepwise gradient of NaCl (0.1, 0.2, 0.3, 0.5, and 0.7 M NaCl) in 0.05 M Tris-HCl buffer at pH 8.3. Fractions eluted at 0.1 and 0.2 M of NaCl contained several proteins with different molecular weights ranging from 75 kDa to low molecular weight fractions according to the SDS-PAGE. Proteins that cleave α- and β-chains of fibrinogen were found in fractions 0.1 and 0.2, indicating the presence of an enzyme with fibrinogenolytic activity in the venom of V. lebetina. The fractions 0.3, 0.5, and 0.7 did not show any significant fibrinogenolytic activity. After platelet aggregation study we concluded that fraction 0.1 contained a protein with fibrinogenolytic activity. An increase in platelet aggregation was observed for the fraction 0.2 after the addition of ADP. This may indicate the presence of an active compound that promotes platelet aggregation. Further research is necessary to determine its nature. Fractions 0.3, 0.5, and 0.7 had no effect on platelet aggregation. A decrease in blood plasma clotting time in APTT to 5 s and 7 s, compared to a control value of 70 s, was shown for fractions eluted at NaCl concentrations of 0.1 M and 0.2 M, respectively. The fractions 0.3, 0.5 had only a slight effect on reducing blood plasma clotting. A slightly increased level of hemolysis was shown in the presence of the unbound fraction and the whole venom. It can be suggested that proteins with phospholipase activity are present in the non-binded fraction. Conclusions. Thus, fibrinogen-specific proteases, hemolytic agents, activators of blood clotting were found in the venom of Vipera lebetina. Most of these compounds must to be purified and can be used for basic biochemical research.

TRANSMISSION ELECTRON MICROSCOPY FOR THE DIRECT ANALYSIS OF FIBRIN CLOT STRUCTURE

The aim of our study was to compare the structure of clots formed as a result of thrombin-induced fibrin polymerization in the presence or absence of monoclonal fibrin-specific antibodies fragments as factors that change the clot structure. We concentrated on the final stage of fibrin clot formation at maximal turbidity point for every sample. Methods. Fibrin polymerization was studied by transmission electron microscopy (TEM) of negatively contrasted samples on H-600 Transmission Electron Microscope (“Hitachi”,Japan); 1% water solution of uranyl acetate (“Merck”, Germany) was used as a negative contrast. For sample preparation, in sterile glass tubes were sequentially added 0.32 mg/mL human fibrinogen, 0.025 M CaCl2 in 0.05 M ammonium formiate buffer (pH 7.9), and a total sample volume was 0.22 mL. The polymerization of fibrin was initiated by the introduction of thrombin at a final concentration of 0.25 NIH/mL. After 180 s, aliquots were taken from the polymerization medium. Each aliquot was diluted to a final fibrinogen concentration of 0.07 mg/mL; 0.01 mL probes of fibrinogen solution were transferred to a carbon lattice, which was treated with a 1% uranyl acetate solution after 2 minutes. Investigations were per-formed using an H-600 electron microscope at 75 kV. Electron microscopic images were obtained at magnification of 20,000 -50,000. Results. Two monoclonal antibodies fragments were obtained towards the mixture of separated Aα-, Bβ- and γ-chains of fibrinogen. Antibodies fragments that were marked as III-1D and I-4A, had different epitopes within fragment Аα105-206 of D-region of fibrinogen. It was shown that addition of antibody fragment I-4A lead to formation of abnormal fibrils that were thinner than in the control sample and were organized in the dense network (Figure). Control sample exhibited the thick fibrils with well-structured classically organized network. The difference between control and I-4A samples demonstrated that antibody I-4A disrupted the structure of polymerized fibrin. In the same time the fibrils obtained in the presence of antibody fragment III-1D were closer to the control ones. Conclusions. TEM is an informative method for the study of the fibrin network formation. Its application allows to estimate the disruption in fi brin formation directly. In a combination with turbidity study and other functional tests TEM can provide important information about molecular mechanisms of clot formation.

Systematic mapping of the conformational landscape and dynamism of soluble fibrinogen

BackgroundFibrinogen is a soluble, multisubunit, and multidomain dimeric protein, which, upon its proteolytic cleavage by thrombin, is converted to insoluble fibrin, initiating polymerization that substantially contributes to clot growth. Fibrinogen contains numerous, transiently accessible “cryptic” epitopes for hemostatic and immunologic proteins, suggesting that fibrinogen exhibits conformational flexibility, which may play functional roles in its temporal and spatial interactions. Hitherto, there have been limited integrative approaches characterizing the solution structure and internal flexibility of fibrinogen. MethodsHere, utilizing a multipronged, biophysical approach involving 2 solution-based techniques, temperature-dependent hydrogen-deuterium exchange mass spectrometry and small angle X-ray scattering, corroborated by negative stain electron microscopy, we present a holistic, conformationally dynamic model of human fibrinogen in solution. ResultsOur data reveal 4 major and distinct conformations of fibrinogen accommodated by a high degree of internal protein flexibility along its central scaffold. We propose that the fibrinogen structure in the solution consists of a complex, conformational landscape with multiple local minima. This is further supported by the location of numerous point mutations that are linked to dysfibrinogenemia and posttranslational modifications, residing near the identified fibrinogen flexions. ConclusionThis work provides a molecular basis for the structural “dynamism” of fibrinogen that is expected to influence the broad swath of its functionally diverse macromolecular interactions and fine-tune the structural and mechanical properties of blood clots.

Fibrinogen-based cell and spheroid sheets manipulating and delivery for mouse hindlimb ischemia

In this research, we introduced a novel strategy for fabricating cell sheets (CSs) prepared by simply adding a fibrinogen solution to growth medium without using any synthetic polymers or chemical agents. We confirmed that the fibrinogen-based CS could be modified for target tissue regardless of size, shape, and cell types. Also, fibrinogen-based CSs were versatile and could be used to form three-dimensional (3D) CSs such as multi-layered CSs and those mimicking native blood vessels. We also prepared fibrinogen-based spheroid sheets for the treatment of ischemic disease. The fibrinogen-based spheroid sheets had much higher in vitro tubule formation and released more angiogenic factors compared to other types of platform in this research. We transplanted fibrinogen-based spheroid sheets into a mouse hindlimb ischemia model and found that fibrinogen-based spheroid sheets showed significantly improved physiological function and blood perfusion rates compared to the other types of platform in this research.

3D printed biomimetic flexible blood vessels with iPS cell-laden hierarchical multilayers

Successful recovery from vascular diseases has typically relied on the surgical repair of damaged blood vessels (BVs), with the majority of current approaches involving the implantation of autologous BVs, which is plagued by donor site tissue damage. Researchers have attempted to develop artificial vessels as an alternative solution to traditional approaches to BV repair. However, the manufacturing of small-diameter (< 6 mm) BVs is still considered one of the biggest challenges due to its difficulty in the precise fabrication and the replication of biomimetic architectures. In this study, we successfully developed 3D printed flexible small-diameter BVs that consist of smooth muscle cells and a vascularized endothelium. In the developed artificial BV, a rubber-like elastomer was printed as the outermost layer of the vessel, which demonstrated enhanced mechanical properties, while and human induced pluripotent stem cell (iPSC)-derived vascular smooth muscle cells (iSMCs) and endothelial cells (iECs) embedded fibrinogen solutions were coaxially extruded with thrombin solution to form cell-laden fibrin gel inner layers. Our results showed that the 3D BVs possessed proper mechanical properties, and the cells in the fibrin layers substantially proliferated over time to form a stable BV construct. Our study demonstrated that the 3D printed flexible small-diameter BV using iPSCs could be a promising platform for the treatment of vascular diseases.

A combination of polyglycolic acid fabric and fibrin glue prevents air leakage from a lung defect.

OBJECTIVESAir leakage after lung resection is a common morbidity that may lengthen hospital stay. Applying sealant to a lesion is an effective prophylaxis in clinical practice. This study aimed to examine the effect of a combination of a bioabsorbable polyglycolic acid (PGA) fabric and fibrin glue (FG) on air sealing by measuring the in vitro mechanical strength and degradation of the fabric, and in vivo histological changes after implantation.METHODSA defect was created in the canine left upper lung lobe, and then filled with a fibrinogen solution and covered with a PGA sheet spray-coated with fibrinogen and thrombin. After 1 and 4 weeks, air leakage from the lesion was examined in vivo under airway pressure. Tissue samples were harvested for histological assessment.RESULTSThe mechanical strength of the PGA fabric remained at 80–90% of the baseline level for 1 week in phosphate-buffered saline, and then rapidly decreased to zero thereafter. Air leakage from the lung defect was prevented by the combination of PGA fabric and FG at 1 and 4 weeks. Histological examinations showed that PGA bundles persisted with a non-specific inflammatory response for 2 weeks and then gradually broke into sparse yarns surrounded by collagen fibres and capillaries by 8 weeks. The lung defect was filled with FG at 1 week and by granulation tissue thereafter.CONCLUSIONSThese results provide evidence for the efficacy of a combination of PGA fabric and FG for the prevention of air leakage in the critical period after lung surgery.

Understanding the complex rheology of human blood plasma

Blood plasma (BP) is a borderline non-Newtonian fluid. Few studies have characterized the rheology of BP and even less focused on understanding its subtle viscoelastic traits, which were only somewhat recently acknowledged. We use passive microrheology to measure the bulk response of human plasma samples under shear at body and ambient temperatures. Evidence of subdiffusive behavior in the mean-squared displacement is observed at the highest frequencies probed, which we attribute to the stress relaxation of protein molecules or chains. Jeffreys-like complex shear moduli were computed thereof. The microenvironments of albumin, fibrinogen, and gamma-globulin solutions (key plasma proteins) were probed as well. Single proteins in an aqueous buffer showed no signs of viscoelasticity within experimental resolution. Conversely, mixed together, they appear to promote the same kind of short-term elastic behavior seen in plasma. All in all, a fresh look at the shear rheology of BP is presented.

Development of an Ultrasmall and Biocompatible Platinum Nanozyme Encapsulated by Zwitterionic Dendrimer for Highly Sensitive Detection of Glucose.

Many kinds of noble metal nanoparticles can mimic the peroxidase-like function of horseradish peroxidase, which results in their wide applications in bio-related detection and drug delivery. However, those metal nanoparticles usually have low stability and reduced catalytic activity in biological complex medium. Herein, a zwitterionic peroxidase-like enzyme has been developed, which has high stability in fibrinogen solutions and high sensitivity for glucose detection. Maleic anhydride, cysteamine, and zwitterionic peptide EKEKC (EK-5) were used to modify generation 5 poly(amido amine) dendrimers (G5 PAMAM) to prepare zwitterionic dendrimer G5MEKnC with nonfouling properties. Finally, the G5MEKnC-encapsulated platinum nanoparticles (Ptn-G5MEK50C) were prepared by entrapping the platinum nanoparticles (1.40 nm) in the catalytic centers in the interior of G5MEK50C. Pt55-G5MEK50C showed high stability in the buffer solution and the fibrinogen solution within 4 days. They also displayed high biocompatibility toward HeLa cells based on cytotoxicity results and morphological observations. Furthermore, the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine with H2O2 by Pt55-G5MEK50C followed the Michaelis-Menten equation, which confirmed their peroxidase-like properties. The catalytic mechanism was due to the generation of •OH from H2O2. More importantly, the peroxidase-like ability of Pt55-G5MEK50C was successfully used to establish a method for the determination of glucose concentration with a broad linear range of 1-2000 μM and a low detection limit of 0.1 μM. This method was highly accurate for the determination of glucose concentration in plasma. The zwitterionic dendrimer template enhanced the properties of Pt55-G5MEK50C. Taken together, a new kind of biocompatible nanozyme has been developed and successfully used for the sensitive detection of glucose in bio-related medium.

Synthesis of Fibrin-Type I Collagen Biomaterials via an Acidic Gel.

Fibrin-Type I collagen composite gels have been widely studied as biomaterials, in which both networks are usually formed simultaneously at a neutral pH. Here, we describe a new protocol in which mixed concentrated solutions of collagen and fibrinogen were first incubated at acidic pH to induce fibrinogen gel formation, followed by a pH change to neutral inducing collagen fiber formation. Thrombin was then added to form fibrin-collagen networks. Using this protocol, mixed gels containing 20 mg.mL−1 fibrin and up to 10 mg.mL−1 collagen could be prepared. Macroscopic observations evidenced that increasing the content of collagen increases the turbidity of the gels and decreases their shrinkage during the fibrinogen-to-fibrin conversion. The presence of collagen had a minor influence on the rheological properties of the gels. Electron microscopy allowed for observation of collagen fibers within the fibrin network. 2D cultures of C2C12 myoblasts on mixed gels revealed that the presence of collagen favors proliferation and local alignment of the cells. However, it interferes with cell differentiation and myotube formation, suggesting that further control of in-gel collagen self-assembly is required to elaborate fully functional biomaterials.

Effect of Low Concentrations of Thrombin on the Dynamic Surface Properties of Fibrinogen Solutions

Effect of Low Concentrations of Thrombin on the Dynamic Surface Properties of Fibrinogen Solutions

A nerve conduit filled with Wnt5a-loaded fibrin hydrogels promotes peripheral nerve regeneration.

AimsPeripheral nerve injury is a significant clinical problem with a substantial impact on quality of life, for which no optimal treatment has been found. This study aimed to analyze the effect and mechanism of Wnt5a‐loaded fibrin hydrogel on a 10‐mm rat sciatic nerve defect.MethodsThe Wnt5a‐loaded fibrin hydrogel was synthesized by mixing a Wnt5a solution with thrombin and fibrinogen solutions. The loading capacity and release profile of Wnt5a‐loaded fibrin hydrogel and the effect of Wnt5a on Schwann cells were evaluated in vitro. We also assessed the in vivo repair status via histological analysis of the regenerative nerve and gastrocnemius muscle, electrophysiological examination, gait analysis, and muscle wet weight.ResultsWe developed a nerve conduit filled with Wnt5a‐loaded fibrin hydrogel (Fn) as a sustained‐release system to repair a 10‐mm rat sciatic nerve defect. In vitro, Wnt5a could promote SC proliferation and the gene expression of vascular endothelial growth factor (VEGF), nerve growth factor (NGF), and cholinergic neurotrophic factor (CNTF), as well as the protein secretion of VEGF and NGF. In vivo, the Wnt5a/Fn group was superior to the hollow, fibrin hydrogel, and Wnt5a groups in terms of axonal growth, myelination, electrophysiological recovery, target organ innervation, and motor function recovery 12 weeks after the operation.ConclusionThe Wnt5a/Fn nerve conduit can promote peripheral nerve defect regeneration, with potential clinical applications. The mechanism for this may be the facilitation of multiple neurotrophin secretion, combining vascularization and neurotrophic growth cues.

Zwitterionic daptomycin stabilized palladium nanoparticles with enhanced peroxidase-like properties for glucose detection

Mimic enzymes, especially noble metal nanomaterials, replace natural horseradish peroxidase due to the artificial regulation of catalytic activity by adjusting particle size and morphology. However, the existing mimic enzymes still have disadvantages such as large particle size, easy clustering and poor biocompatibility. Herein, well-dispersed daptomycin stabilized palladium nanoparticles (Dap-Pdn NPs) were synthesized by using daptomycin as a biological template. The average particle size of palladium nanoparticles of Dap-Pd0.25 NPs was 1.73 nm, the hydrodynamic size of Dap-Pd0.25 NPs detected by DLS method was 49.97 nm, Dap-Pd0.25 NPs were stable in fibrinogen solution. In addition, Dap-Pd0.25 NPs had excellent peroxidase-like activity, which effectively catalyzed the colorimetric oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2. Dap-Pd0.25 NPs were used to detect glucose concentration based on the colorimetric reaction of TMB, which had a wide detection range (0.02–1 mM) and low detection limit (5.6 μM) for glucose. Besides, fluorescence experiments proved that Dap-Pdn NPs catalyzed H2O2 to generate·OH. Taken together, a simple, green and inexpensive synthesis method of palladium nanoparticles with enhanced peroxidase-like activity was proved in this research. Dap-Pdn NPs will have great application prospects in biological detection in the future.

Doxorubicin-loaded natural daptomycin micelles with enhanced targeting and anti-tumor effect invivo.

Development of a simple method to enhance targeting and anti-tumor effect of the chemotherapeutic agents invivo is a major problem. Amphipathic and natural daptomycin is biocompatible antibacterial polypeptide used in clinical practice. Herein, doxorubicin (DOX) was stabilized by zwitterionic daptomycin (Dap) micelles in aqueous solution to form a zwitterionic nanodrug (Dap-DOX micelles). The hydrodynamic size and zeta potential of Dap-DOX micelles were 85nm and-10 mV, respectively. The study on the controlled release showed that more DOX molecules were released from Dap-DOX micelles at acidic condition of tumor tissue than that at neutral condition of normal tissue which was due to pH responsiveness of Dap-DOX micelles. Dap-DOX micelles exhibited good stability in fibrinogen solution. Moreover, MTT studies showed that Dap-DOX micelles had higher cytotoxicity than free DOX. Notably, the results of flow cytometry indicated that the average fluorescence intensity of Dap-DOX micelle-treated cells was higher than that of free DOX-treated cells, and acidic conditions were more favorable for Dap-DOX micelles than normal pH in cell uptake assay. More importantly, Dap-DOX micelles were biocompatible invivo based on the changes of weight and blood indexes of mice. Dap-DOX micelles were selectively accumulated at tumor sites invivo through EPR effect, which reduced the toxicity of free DOX and achieved excellent tumor inhibition effect. The tumor inhibition rate of Dap-DOX micelles reached 96%. Dap-DOX micelles also effectively inhibited the growth of bacterial. Taken together, Dap-based drug delivery systems are promising and effective in cancer therapy.