Composite Microfluidic Petri Dish-Chip (MPD-Chip) without Protein Coating for 2D Cell Culture.

Hydrophilicity is a requisite attribute for the 2D cell culture substrate's surface, facilitating cell adhesion and spreading. Conventional poly(dimethylsiloxane) (PDMS) microfluidic chips necessitate protein coatings to enhance hydrophilicity; however, this approach is afflicted by issues of transient efficacy, interference with cell analysis, and high costs. This paper presents a protein-free microfluidic chip, termed a "microfluidic Petri dish-chip (MPD-chip)", integrating PDMS as the cover and a tissue culture-treated (TC-treated) Petri dish as the substrate. Microstructures are hot-embossed onto the Petri dish substrate using a silicon mold. This meticulous replication process serves to establish stable flow field dynamics within the chip. A simplified method for irreversible bonding, utilizing plasma activation and silylation, is proposed for affixing the PDMS cover onto the microstructured Petri dish substrate. The prepared composite chip exhibits remarkable tightness, boasting a notable bond strength of 2825 kPa. Furthermore, the composite microfluidic chip demonstrates the capability to withstand flow velocities of at least 200 µL/min, effectively meeting the required injection standards for both cell suspension and culture medium. SH-SY5Y and HeLa cells are cultured dynamically in the MPD-chip and control groups. Outcomes encompassing normalized cell density, cell adhesion area, and cell viability metrics unequivocally highlight the superiority of the MPD-chip in facilitating long-term two-dimensional (2D) cell cultures.

[Effects of AdipoRon orally on the functions of spleen and pancreas in type 2 diabetic mice].

OBJECTIVE: To observe the effects of AdipoRon orally on the functions of spleen and pancreas in type 2 diabetic mice, in order to present data for clinical application. METHODS: Forty C57/BL6 male mice were randomly divided into 2 groups: normal control group (n=10) and model group (n=30), the former group was fed normally, while the later group was fed with high fat and sugar for 4 weeks.After that, type 2 diabetes model was established in DM group induced by intraperitoneal injection of streptozotocin (STZ, 40 mg/kg).As type 2 diabetes model established successfully, the model mice were randomly divided into three groups (n=10): diabetes mellitus (DM) group, high dose of AdipoRon group (DM + H) and low dose of adiponRon group (DM + L).All the four groups were treated with saline, saline, AdipoRon at the doses of 20 mg/kg and 50 mg/kg by gavages respectively, once a day for 10 days.And then put them to death for collecting blood, pancreas and spleen.Pathological changes of pancreas were observed with a light microscope after HE staining.Protein contents of insulin receptor (INSR), insulin receptor substrate 1( IRS-1) and tumor necrosis factor-α(TNF-α) in pancreatic and spleen tissues were detected by ELISA.The protein level of phosphorylation insulin receptor substrate 1(p-IRS-1) in pancreas was determined by Western blot, and the expression of insulin mRNA in pancreas was tested by RT-PCR. RESULTS: Under the light microscope, it was visible that the pancreatic tissue in NC group was full and closely packed, and the islet was big.Pancreatic tissue of DM mice was incompact and the islet of DM mice was smaller than that of normal mice.As for the mice treated with AdipoRon orally, the pancreatic tissue was full and closely arranged, and the islet was slightly smaller.Compared with NC group, the levels of TNF-α in pancreas and spleen of DM group were increased markedly, the levels of INSR and IRS-1 were decreased, the spleen coefficient, p-IR-1 protein level and insulin mRNA expression in pancreas were decreased, all were significant statistically (P＜0.05).Compared with DM group, the levels of TNF-α in pancreas and spleen of AdipoRon groups were decreased, the levels of INSR and IRS-1 in pancreas and spleen of AdipoRon groups were increased, while the spleen coefficient was increased (P＜0.05).The p-IRS-1 protein level and insulin mRNA expression in pancreas in DM+H group were increased (P＜0.05).Compared with DM + L group, the level of TNF-α was decreased, and the levels of INSR and IRS-1 were significantly increased (P＜0.05) in DM + H group (P＜0.05). CONCLUSION: Oral administration of AdipoRon can protect the spleen and pancreas of diabetic mice by decreasing the inflammatory response, up-regulating the expression of INSR, and increasing p-IRS-1 level in diabetic mice.

[The intervention effects of AdipoRon on renal injury in type 2 diabetic mice].

OBJECTIVE: To study the effects of adiponin receptor agonist (AdipoRon) on renal injury in type 2 diabetic mice. METHODS: The experiment was carried out on 40 SPF C57/BL6 male mice and they were randomly divided into normal control group (n=10) and experimental group (n=30). Mice in experimental group were given with high sugar and high fat feed in combination with only an intraperitoneal injection of small dose of streptozotocin to build the model of type 2 diabetes (T2DM), which were randomly divided into three groups, model control group (DM), low dose AdipoRon group (DM + L) and high dose AdipoRon group (DM+H)(n=10). Then the change of blood glucose was detected. The serum levels of insulin receptor (INSR), insulin receptor substrate-1 (IRS-1) and tumor necrosis factor-α (TNF-α) in mice were measured by ELASA. Pathological changes of renal tissues were observed with a light microscope after HE staining. The expressions of pancreatic duodenal homebox-1 (PDX-1) and insulin mRNA in renal tissues were detected by RT-PCR. The content of phosphated insulin receptor substrate-1 (p-IRS-1) protein in the kidney was determined by Western blot. RESULTS: Compared with DM mice, blood glucose and TNF-α levels in DM + H mice and DM + L mice were significantly reduced (P<0.05), while the expressions of INSR,IRS-1 and the content of p-IRS-1 were increased markedly(P<0.05), and the expressions of PDX-1 and insulin mRNA in renal tissue were increased significantly(P<0.05, P<0.01). CONCLUSIONS: Mice treated with AdipoRon have lower blood glucose and TNF-α levels, and higher protein expression levels of INSR, IRS-1, and higher mRNA expression levels of PDX-1 and insulin, and the content of p-IRS-1. All of these indicate that AdipoRon has a certain effects on renal injury in type 2 diabetic mice.

Protein profiling and functional analysis of liver mitochondria from rats with nonalcoholic steatohepatitis.

Mitochondrial dysfunction is closely associated with the pathogenesis of nonalcoholic steatohepatitis (NASH). The aim of the present study was to comprehensively determine mitochondrial abnormalities in NASH by detecting the proteomics in liver mitochondria in a NASH rat model, which was induced for 16 weeks by the provision of a high fat and high cholesterol diet (HFD). Serum parameters, including triglycerides, total cholesterol, low­density lipoprotein cholesterol and high­density lipoprotein cholesterol were determined, and hematoxylin and eosin staining of liver tissues was examined to evaluate the NASH rat model. Various parameters associated with mitochondrial function were examined, including mitochondrial DNA (mtDNA) copy number, mitochondrial membrane potential (MMP) and mitochondrial respiratory chain complex (MRC) activity. The mitochondrial proteomics were analyzed and identified using isobaric tags for relative and absolute quantitation labeling coupled with two­dimensional liquid chromatography­tandem mass spectrometry. The identified proteins were classified and grouped using the Blast2GO program against the non­redundant protein database, the Kyoto Encyclopedia of Genes and Genomes database and the Cluster of Orthologous Groups of proteins database. Compared with the control, mtDNA copy number, MMP, and activities of MRC I and III were decreased markedly in the HFD group. A total of 18 upregulated and 13 downregulated proteins were identified, with a significant 1.2­fold difference between the control and NASH groups. The dysregulated proteins were closely involved in mitochondrial oxidative phosphorylation, the lipid metabolic process and fatty acid ß­oxidation. The results of the present study provide important proteomic information regarding liver mitochondria in NASH and serve as a basis for further detailed investigations of the pathogenesis of NASH.

[The effect of AdipoRon on insulin sensitivity of mouse skeletal muscle cells and its mechanism].

OBJECTIVE: To observe the effect of AdipoRon, an adiponin receptor agonist, on insulin sensitivity in mouse myoblast cell line (C2C12) and to explore its mechanism. METHODS: C2C12 was induced to differentiate into myoblasts by using horse serum. Then the cells were divided into 6 groups (9 double wells):blank control group, high dose AdipoRon group, low dose AdipoRon group, insulin group and the low dose AdipoRon with PI3K inhibitor (phosphatidylinositol 3 kinase) group and the insulin with PI3K inhibitor group. After cultured for 12 h, the supernatant was collected and glucose consumption was measured. Cell proliferation was tested by using CCK8. In the 6-well plate, C2C12 was induced to differentiate into myoblasts. The drug was incubated for 12 h and the mRNA level of GLUT4 was detected by RT-PCR. RESULTS: Compared with the blank control group, the levels of glucose consumption in high dose AdipoRon group, low dose AdipoRon group and insulin group was increased significantly (P<0.05). After adding PI3K inhibitor, the levels of glucose consumption in the above mentioned three groups were not different from that in blank control group. high dose AdipoRon group, low dose AdipoRon group and insulin group had proliferation, but only the insulin group was statistically significant (P<0.05). Compared with the control group, the levels of GLUT4 mRNA in AdipoRon high dose group, low dose AdipoRon group and insulin group were all higher than those in control group (P<0.05). After adding PI3K inhibitor, GLUT4 mRNA level was not statistically significant compared with blank control group. CONCLUSIONS: AdipoRon can increase the consumption of glucose without affecting cell proliferation, which may play a role in improving insulin sensitivity, but the specific mechanism remains to be further studied.

[Intervention effects of oral active AdipoRon on liver oxidative stress in type 2 diabetic mice].

OBJECTIVE: To explore the intervention effects of oral active AdipoRon on liver oxidative stress in type 2 diabetic mice, which provides basic data for clinical application. METHODS: Thirty-two healthy male C57BL/6 mice were divided into 4 groups:normal group (NC, n=8), diabetes mellitus group (DM, n=8), high dose AdipoRon treatment group (DM + H, n=8) and low dose AdipoRon treatment group (DM + L, n=8). Following six weeks high fat feed, mice of DM, DM + H and DM + L were intraperitoneally injected with 40 mg/kg streptozocin (STZ), leading to type 2 diabetes. Afterwards, DM + H group and DM + L group were continuously treated with high dose and low doses of oral AdipoRon respectively for 10 days, following which, related biochemical indicators were detected. Western blot method was used to detect the p-IRS-1 protein expression in liver tissue and RT-PCR method to detect PDX-1 mRNA expression in the pancreas. RESULTS: The blood glucose of DM group was obviously higher than that of NC group (P < 0.05). Compared to that of DM group, blood glucose of DM + H group as well as DM + L group was significantly lower. Activity of superoxide dismutase (SOD), catalase (CAT) in liver tissue of DM mice was significantly lower than that of NC group (P < 0.05); activity of malondialdehyde (MDA) and nitric oxide synthase (NOS) in DM group significantly higher than that of NC group (P < 0.05); activity of SOD and CAT in DM + L group and DM + H group obviously higher than DM group (P < 0.05); activity of MDA and NOS in DM + L group and DM + H group significantly lower than DM group (P < 0.05). And the p-IRS-1 protein expression in liver tissue and PDX-1 mRNA level in pancreas increased significantly (P < 0.05). CONCLUSIONS: Oral active Adi-poRon which reduced the blood glucose levels of mice had a certain intervention effect on liver tissue oxidative stress in type 2 diabetes mice.

[AdipoRon for the treatment of type 2 diabetes in mice and its possible mechanism of the liver].

OBJECTIVE: To observe the effect of AdipoRon for the treatment of type 2 diabetes (T2DM)in mice and its effect on the liver. METHODS: Forty male C57/BL6 mice (SPF) were randomly divided to normal control (NC) group and the experimental group. To establish the T2DM mice model, mice in the experimental group were fed with high fat and high glucose, combined with intraperitoneal injection of streptozotocin (STZ) in small doses, and mice were further subdivided into model control (DM) group, model control with low AdipoRon (DM+L) group and model control with high AdipoRon (DM+H) group (n=10). Serum indexes, such as levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) were detected biochemically and the morphological changes of liver cells were observed with HE staining and expression of liver carbohydrate related gene (PEPCK) were determined by real-time fluorescence quantitative PCR (real time FQ-PCR). RESULTS: Compared with mice in the DM group, levels of ALT, AST, ALP, triglyceride (TG), glucose (GLU) reduced in DM+L and DM+H group (P<0.05). Concentrations of serum free fatty acids (FFA) in DM+L and DM+H group reduced significantly (P<0.05). Besides, concentrations of liver glucose-6-phosphatase (G-6-P) in the mice of DM+L group reduced significantly, while there was no significant difference in the content of G-6-P between the mice of DM+H group and the mice of DM group. Furthermore, the expression of the liver phosphoenolpyruvate carboxylase (PEPCK) in the DM+H group reduced significantly (P<0.05). Compared with the DM group no significant change was found in the PEPCK expression between DM+L and DM group. CONCLUSIONS: The serum indexes such as levels of ALT, AST, ALP, TG, Glu, G-6-P and PEPCK were all reduced in DM mice treated with AdipoRon, indicating the obvious protecting effect of AdipoRon on the liver in DM mice.

[Effects of pirfenidone on hepatic fibrosis in mice induced by carbon tetrachloride].

OBJECTIVE: To investigate the effects of pirfenidone on CCl4-induced liver fibrosis in mice. METHODS: After 8-week feeding, 40 healthy male SPF ICR mice were randomly divided into 4 groups:liver fibrosis group (CCL4 group), low doses of Pirfenidone group (PFD-L group), high doses of Pirfenidone group (PFD-H group) and control group. The mice in CCL4 group, low doses of Pirfenidone group (PFD-L group), high doses of Pirfenidone group (PFD-H group) were injected intraperitoneally with 0.4 ml 10% CCL4 solution dissolved in soybean oil. Then the PFD-L and PFD-H groups were treated with 120 mg and 240 mg PFD via gastric gavage, respectively. Control group was injected with same volume of saline. Alanine aminotransferase(ALT), aspartate aminotransferase(AST), alkaline phosphatase(ALP) in serum were tested with automatic biochemistry analyzer and the pathologic changes of liver tissue were examined by HE staining. Furthermore, we identi-fied hyaluronic acids(HA), laminin(LN), collagentype IV(IV-C) in serum using radioimmunoassay and the expression of smooth muscle acti-nalpha(α-SMA) related gene in liver was tested by real-time fluorescence quantitative PCR. RESULTS: Compared with control group, hepatic lobules in CCL4 mice were damaged significantly, collagenous fiber was deposited obviously, and counterfeit hepatic lobules formed. The serum levels of ALT, AST, ALP were increased obviously (P<0.05) with the enhancement of HA, LN, IV-C in serum (P<0.05) and the ex-pression of α-SMA related gene (P<0.05). Compared to CCL4-treated mice, the serum levels of ALT, AST, ALP in PFD-L and PFD-H groups were decreased, HA, LN, IV-C in PFD-L and PFD-H mice went down obviously,and the expression of α-SMA related gene was con-trolled (P<0.05). From pathological observation, we found the degree of liver fibrosis in PFD-L mice was reduced and collagenous fiber was decreased, only a little counterfeit hepatic lobule could be found. Cell arrangement in PFD-H mice recovered, the structural of hepatic lobules disordered and no obvious counterfeit hepatic lobules were found. Therefore, the recovery of PFD-H group was better than PFD-L group. CONCLUSIONS: Pirfenidone has a protective role in improving the outcome of the liver fibrosis and it may become a new direction of early intervention in liver fibrosis.

Redox and acid-base chemistry of 7,7,8,8-tetracyanoquinodimethane, 7,7,8,8-tetracyanoquinodimethane radical anion, 7,7,8,8-tetracyanoquinodimethane dianion, and dihydro-7,7,8,8-tetracyanoquinodimethane in acetonitrile.

The chemistry and electrochemistry of TCNQ (7,7,8,8-tetracyanoquinodimethane), TCNQ(•-), TCNQ(2-), and H(2)TCNQ in acetonitrile (0.1 M Bu(4)NPF(6)) solution containing trifluoroacetic acid (TFA) has been studied by transient and steady-state voltammetric methods with the interrelationship between the redox and the acid-base chemistry being supported by simulations of the cyclic voltammograms. In the absence of acid, TCNQ and its anions undergo two electrochemically and chemically reversible one-electron processes. However, in the presence of TFA, the voltammetry is considerably more complex. The TCNQ(2-) dianion is protonated to form HTCNQ(-), which is oxidized to HTCNQ(•), and H(2)TCNQ which is electroinactive over the potential range of -1.0 to +1.0 V versus Ag/Ag(+). The monoreduced TCNQ(•-) radical anion is weakly protonated to give HTCNQ(•), which disproportionates to TCNQ and H(2)TCNQ. In acetonitrile, H(2)TCNQ deprotonates slowly, whereas in N,N-dimethylformamide or tetrahydrofuran, rapid deprotonation occurs to yield HTCNQ(-) as the major species. H(2)TCNQ is fully deprotonated to the TCNQ(2-) dianion in the presence of an excess concentration of the weak base, CH(3)COOLi. Differences in the redox and acid-base chemistry relative to the fluorinated derivative TCNQF(4) are discussed in terms of structural and electronic factors.

Synthesis and structural characterization of a TCNQ based organic semi-conducting material with a 2:5 stoichiometry.

The tetrabutylammonium complex with a 2:5 stoichiometry, (n-Bu(4)N)(2)(TCNQ)(5), has been prepared and structurally characterized by X-ray crystallography. Diagnostic bands in the Raman spectrum and signature features in the electrochemistry confirm that the TCNQ moieties are partially charged in the solid state. EPR, magnetic susceptibility, and electrical conductivity measurements are all consistent with (n-Bu(4)N)(2)(TCNQ)(5) behaving as a quasi-one-dimensional organic semiconductor.

Two-step electrochemically directed synthesis of Pr4N(TCNQ)n (n=1, 2): preparation, structure, and properties of a magnetically isolated dimer and a quasi-one-dimensional chain.

Solid-state electrochemistry of a tetracyanoquinodimethane (TCNQ)-modified electrode in contact with a tetrapropylammonium cation (Pr(4)N(+)) electrolyte showed two electron-transfer steps to give Pr(4)N(TCNQ)(2) (1) and Pr(4)N(TCNQ) (2) rather than the traditional one-electron step to directly give Pr(4)N(TCNQ). Two thermodynamically stable Pr(4)N(+)-TCNQ stoichiometries, 1 and 2, were synthesized and characterized. The degree of charge transfer (ρ) calculated from the crystal structure is -0.5 for the TCNQ moieties in 1 and -1.0 for those in 2. Raman spectra for Pr(4)N(TCNQ)(2) show only one resonance for the extracyclic C=C stretching at 1423 cm(-1), which lies approximately midway between that of TCNQ at 1454 cm(-1) and TCNQ(-) at 1380 cm(-1). Both the magnetic susceptibility and EPR spectra are temperature-dependent, with a magnetic moment close to that for one unpaired electron per (TCNQ)(2) unit in 1, whereas 2 is almost diamagnetic. Pressed discs of both complexes show conductivity (1-2×10(-5) S cm(-1)) in the semiconductor range. For 1, the position of zero current for the steady-state voltammograms implies 50% of TCNQ(-) and 50% TCNQ(0) is present in solution, thereby supporting a dissociation of (TCNQ)(2)(-) in solution, but is indicative of only TCNQ(-) being present for 2.

Detailed electrochemical analysis of the redox chemistry of tetrafluorotetracyanoquinodimethane TCNQF4, the radical anion [TCNQF4]•-, and the dianion [TCNQF4]2- in the presence of trifluoroacetic acid.

The electrochemistry of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (TCNQF(4)), [TCNQF(4)](•-), and [TCNQF(4)](2-) have been studied in acetonitrile (0.1 M [Bu(4)N][ClO(4)]). Transient and steady-state voltammetric techniques have been utilized to monitor the generation of [TCNQF(4)](•-) and [TCNQF(4)](2-) anions as well as their reactions with trifluoroacetic acid (TFA). In the absence of TFA, the reduction of TCNQF(4) occurs via two, diffusion controlled, chemically and electrochemically reversible, one-electron processes where the reversible formal potentials are 0.31 and -0.22 V vs Ag/Ag(+). Unlike the TCNQ analogues, both [TCNQF(4)](•-) and [TCNQF(4)](2-) are persistent when generated via bulk electrolysis even under aerobic conditions. Voltammetric and UV-vis data revealed that although the parent TCNQF(4) does not react with TFA, the electrochemically generated radical anion and dianion undergo facile protonation to yield [HTCNQF(4)](•), [HTCNQF(4)](-) and H(2)TCNQF(4) respectively. The voltammetry can be simulated to give a complete thermodynamic and kinetic description of the complex, coupled redox and acid-base chemistry. The data indicate dramatically different equilibrium and rate constants for the protonation of [TCNQF(4)](•-) (K(eq) = 3.9 × 10(-6), k(f) = 1.0 × 10(-3) M(-1) s(-1)) and [TCNQF(4)](2-) (K(eq) = 3.0 × 10(3), k(f) = 1.0 × 10(10) M(-1) s(-1)) in the presence of TFA.

Noncovalent functionalization of multiwalled carbon nanotubes: application in hybrid nanostructures.

We developed a reproducible, noncovalent strategy to functionalize multiwalled carbon nanotubes (MWNTs) via embedding nanotubes in polysiloxane shells. (3-Aminopropyl)triethoxysilane molecules adsorbed to the nanotube surfaces via hydrophobic interactions are polymerized simply by acid catalysis and form a thin polysiloxane layer. On the basis of the embedded MWNTs, negatively charged gold nanoparticles are anchored to the nanotube surfaces via electrostatic interactions between the protonated amino groups and the gold nanoparticles. Furthermore, these gold nanoparticles can further grow and magnify along the nanotubes through heating in HAuCl4 aqueous solution at 100 degrees C; as a result these nanoparticles are joined to form continuous gold nanowires with MWNTs acting as templates.

In situ synthesis and characterization of multiwalled carbon nanotube/Au nanoparticle composite materials.

An effective and facile in situ reduction approach for the fabrication of carbon nanotube-supported Au nanoparticle (CNT/Au NP) composite nanomaterials is demonstrated in this article. Linear polyethyleneimine (PEI) is ingeniously used as both a functionalizing agent for the multiwalled carbon nanotubes (MWNTs) and a reducing agent for the formation of Au NPs. This method involves a simple mixing process followed by a mild heating process. This approach does not need the exhaustive surface oxidation process of CNTs. The coverage of Au NPs on CNTs is tunable by varying the experimental parameters, such as the initial molar ratio of PEI to HAuCl4, the relative concentration of PEI and HAuCl4 to MWNTs, and the temperature and duration of the heat treatment. More importantly, even the heterogeneous CNT/Au composite nanowires are obtainable through this method. TEM, XPS, and XRD are all used to characterize the CNT/Au composite materials. In addition, the optical and electrocatalytic properties are investigated.

Surface-enhanced resonance Raman spectroscopy and spectroscopy study of redox-induced conformational equilibrium of cytochrome c adsorbed on DNA-modified metal electrode.

The redox-induced conformational equilibrium of cytochrome c (cyt c) adsorbed on DNA-modified metal electrode and the interaction mechanism of DNA with cyt c have been studied by electrochemical, spectroscopic and spectroelectrochemical techniques. The results indicate that the external electric field induces potential-dependent coordination equilibrium of the adsorbed cyt c between its oxidized state (with native six-coordinate low-spin and non-native five-coordinate high-spin heme configuration) and its reduced state (with native six-coordinate low-spin heme configuration) on DNA-modified metal electrode. The strong interactions between DNA and cyt c induce the self-aggregation of cyt c adsorbed on DNA. The orientational distribution of cyt c adsorbed on DNA-modified metal electrode is potential-dependent, which results in the deviation from an ideal Nernstian behavior of the adsorbed cyt c at high electrode potentials. The electric-field-induced increase in the activation barrier of proton-transfer steps attributed to the rearrangement of the hydrogen bond network and the self-aggregation of cyt c upon adsorption on DNA-modified electrode strongly decrease the interfacial electron transfer rate. In addition, the strongly Coulombic interactions between DNA and cyt c only disturb the microenvironment of the heme, and do not affect the states of heme ligation and spin. The secondary structure of the adsorbed cyt c is retained, while the conformation of DNA is changed from the B form DNA to A form DNA.

Facile preparation of amperometric laccase biosensor with multifunction based on the matrix of carbon nanotubes-chitosan composite.

The carbon nanotubes-chitosan (CNTs-CS) composite provides a suitable biosensing matrix due to its good conductivity, high stability, and good biocompatibility. Enzymes can be firmly incorporated into the matrix without the aid of other cross-linking reagents. The composite is easy to form insoluble film in solution above pH 6.3. Based on this, a facilely fabricated amperometric biosensor by entrapping laccase into the CNTs-CS composite film has been developed. At pH 6.0, the fungi laccase incorporated into the composite film remains better catalytic activity than that dissolved in solution. The system is in favor of the accessibility of substrate to the active site of laccase, thus the affinity to substrates is improved greatly, such as 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS), catechol, and O2 with Km values of 19.86 microM, 9.43 microM, and 3.22 mM, respectively. The major advantages of the as-prepared biosensor are: detecting different substrates (ABTS, catechol, and O2), possessing high affinity and sensitivity, durable long-term stability, and facile preparation procedure. On the other hand, the system can be applied in fabrication of biofuel cells as the cathodic catalysts based on its good electrocatalysis for oxygen reduction. It can be extended to immobilize other enzymes and biomolecules, which will greatly facilitate the development of biosensors, biofuel cells, and other bioelectrochemical devices.

Parallel alignment of carbon nanotubes induced with inorganic molecules.

In this work, a new strategy is presented to form ordered multiwalled carbon nanotube (MWNT) arrays. The MWNTs are aligned horizontally and parallel in (3-aminopropyl)triethoxysilane (3-APTES) sol films on the surface of mica and glassy carbon (GC). 3-APTES is ready to form charged rodlike micelles, which play a key role in fabricating orderly MWNT arrays. Moreover, we prepare MWNT arrays on the surfaces of solid electrodes and detect the electrochemical response of the microarray electrodes for the Fe(CN)(6)3-/Fe(CN)6(4-) couple.

Small molecules as cross-linkers: fabrication of carbon nanotubes/thionine self-assembled multilayers on amino functionalized surfaces.

Electroactive and photoactive thionine molecules have been selected as cross-linkers to construct self-assembled multilayers containing carbon nanotubes (CNTs)via the alternate layer deposition technique. The resulting multilayer system can electrocatalyze the oxidation of NADH and offer potential applications in other fields such as biosenors and photovoltaic devices.

A colloidal Au monolayer modulates the conformation and orientation of a protein at the electrode/solution interface.

The orientation and conformation of adsorbed cytochrome c (cyt c) at the interface between an electrode modified with colloidal Au and a solution were studied by electrochemical, spectroscopic, and spectroelectrochemical techniques. The results indicate that the colloidal Au monolayer formed via preformation of an organic self-assembled monolayer (SAM) can increase the electronic coupling between the SAM and cyt c in the same manner as bifunctional molecular bridges, one functional group of which is bound to the electrode surface while the other interacts with the protein surface. The approach of cyt c to the modified electrode/solution interface can be assisted by strong interactions of the intrinsic charge of colloidal particles with cyt c, while the heme pocket remains almost unchanged due to the screening effect of the negatively charged field created by the intrinsic charge. The conformational changes of cyt c induced by its adsorption at a bare glassy carbon electrode/solution interface and the effect of the electric field on the ligation state of the heme can be avoided at the colloidal-Au-modified electrode/solution interface. Finally, a possible model for the adsorption orientation of cyt c at the colloidal-Au-modified electrode/solution interface is proposed.