Sp2-hybridized Carbon Atoms Research Articles

Insights into controllable electronic properties of 2D type-II Twin-Graphene/g-C3N4 and type-I Twin-Graphene/hBN vertical heterojunctions via external electric field and strain engineering

Twin-graphene (Twin-G), an accessible carbon allotrope composed of sp2 hybridized carbon atoms, has attracted considerable interest due to its intrinsic bandgap and tunable electronic properties. This work evaluates the near-edge electronic structures and the carrier mobility of the Twin-G/g-C3N4 and Twin-G/hBN vdW heterojunctions employing the first-principles calculations. The results demonstrate that Twin-G/g-C3N4 retains a staggered type-II alignment, which may benefit the highly-efficient photogenerated carrier separation. Whereas the Twin-G/hBN exhibits type-I alignment. An external electrical field induces a semiconductor-to-metal and indirect-to-direct gap transition in Twin-G/g-C3N4 heterostructure. The type-II-to-type-I transition in Twin-G/g-C3N4 under tensile strain can be understood from the near-gap wave functions morphology. G-C3N4 substrate has a more significant effect to enhance the carrier mobility of Twin-G. The electron mobility along the zigzag-direction in Twin-G/g-C3N4 is ∼1751 cm2V−1s−1, far surpassing that of Twin-G monolayer. These results open up promising opportunities for the development of optoelectronic devices based on the Twin-G heterostructures.

Mechanism of superlubricity of a DLC/Si3N4 contact in the presence of castor oil and other green lubricants

To meet the surging needs in energy efficiency and eco-friendly lubricants, a novel superlubricious technology using a vegetable oil and ceramic materials is proposed. By coupling different hydrogen-free amorphous carbon coatings with varying fraction of sp2 and sp3 hybridized carbon in presence of a commercially available silicon nitride bulk ceramic, castor oil provides superlubricity although the liquid vegetable oil film in the contact is only a few nanometres thick at most. Besides a partial liquid film possibly separating surfaces in contact, local tribochemical reactions between asperities are essential to maintain superlubricity at low speeds. High local pressure activates chemical degradation of castor oil generating graphitic/graphenic-like species on top of asperities, thus helping both the chemical polishing of surface and its chemical passivation by H and OH species. Particularly, the formation of the formation of −(CH2−CH2)n− noligomers have been evidenced to have a major role in the friction reduction. Computer simulation unveils that formation of chemical degradation products of castor oil on friction surfaces are favoured by the quantity of sp2-hybridized carbon atoms in the amorphous carbon structure. Hence, tuning sp2-carbon content in hydrogen-free amorphous carbon, in particular, on the top layers of the coating, provides an alternative way to control superlubricity achieved with castor oil and other selected green lubricants.

Constructing two-dimensional holey graphyne with unusual annulative π-extension

•A two-dimensional carbon allotrope of holey graphyne (HGY) was designed •1,3,5-tribromo-2,4,6-triethynylbenzene was synthesized for fabrication of HGY •HGY comprised a pattern of six-vertex and highly strained, eight-vertex rings •HGY’s direct p-type semiconductor with high carrier mobility was simulated Here, we report two-dimensional, single-crystalline holey graphyne (HGY) synthesized in an interfacial two-solvent system through a Castro-Stephens-type coupling reaction from 1,3,5-tribromo-2,4,6-triethynylbenzene. As a new type of 2D carbon allotrope, HGY is alternately linked between benzene rings and C≡C bonds and is composed of a pattern of six-vertex and highly strained, eight-vertex rings and an equal percentage of sp2 and sp hybridized carbon atoms. By combining experimental and theoretical studies, we systematically investigated the stability of HGY and its vibrational and optical properties. Density functional theory computations predicted that HGY is a p-type semiconductor that embraces a direct bandgap (∼1.1 eV) with a high carrier mobility. Transmission electron microscopic studies revealed that the synthesized HGY sheets are highly crystalline with AB stacking. Its semiconducting character, nonlinear sp bonding, and special π-conjugated structure endow HGY with promising applications in optoelectronic, energy harvesting, gas separation, catalysis, water remediation, sensor, and energy-related fields. Here, we report two-dimensional, single-crystalline holey graphyne (HGY) synthesized in an interfacial two-solvent system through a Castro-Stephens-type coupling reaction from 1,3,5-tribromo-2,4,6-triethynylbenzene. As a new type of 2D carbon allotrope, HGY is alternately linked between benzene rings and C≡C bonds and is composed of a pattern of six-vertex and highly strained, eight-vertex rings and an equal percentage of sp2 and sp hybridized carbon atoms. By combining experimental and theoretical studies, we systematically investigated the stability of HGY and its vibrational and optical properties. Density functional theory computations predicted that HGY is a p-type semiconductor that embraces a direct bandgap (∼1.1 eV) with a high carrier mobility. Transmission electron microscopic studies revealed that the synthesized HGY sheets are highly crystalline with AB stacking. Its semiconducting character, nonlinear sp bonding, and special π-conjugated structure endow HGY with promising applications in optoelectronic, energy harvesting, gas separation, catalysis, water remediation, sensor, and energy-related fields.

A Unified Synthetic Strategy to Introduce Heteroatoms via Electrochemical Functionalization of Alkyl Organoboron Reagents

Based on systematic electrochemical analysis, an integrated synthetic platform of C(sp3)-based organoboron compounds was established for the introduction of heteroatoms. The electrochemically mediated bond-forming strategy was shown to be highly effective for the functionalization of sp3-hybridized carbon atoms with significant steric hindrance. Moreover, virtually all the nonmetallic heteroatoms could be utilized as reaction partners using one unified protocol. The observed reactivity stems from the two consecutive single-electron oxidations of the substrate, which eventually generates an extremely reactive carbocation as the key intermediate. The detailed reaction profile could be elucidated through multifaceted electrochemical studies. Ultimately, a new dimension in the activation strategies for organoboron compounds was accomplished through the electrochemically driven reaction development.

Synthesis of sp-hybridized nitrogen doped ultrathin graphdiyne and application to the electrochemical detection for 6,7-dihydroxycoumarin.

As a new type of carbon nanomaterial, graphdiyne (GDY) has unique sp hybridized carbon atom, which makes it possible to develop new nitrogen-doped configurations. In this paper, sp-hybridized nitrogen atom doped ultrathin graphdiyne (NUGDY) was prepared based on graphdiyne oxide and melamine by carbonization at high temperature. NUGDY not only preserves the typical folded and wrinkled two-dimensional morphology of GDY, but also presents a three-dimensional porous network structure, which provides sufficient interface and capacity for the loading of target analyte. Meanwhile, N doping increases the GDY defects with more active sites and higher conductivity. Then, NUGDY was modified on the surface of carbon ionic liquid electrode and the modified electrode was applied to 6,7-dihydroxycoumarin (6,7-DHC) analysis. Cyclic voltammetry, electrochemical impedance spectroscopy and chronocoulometry results show that NUGDY has good promotive effect to the electrode performances. Differential pulse voltammetric experiments show that this electrochemical sensor has a low detection limit as 2.3nM (3S0/S) for 6,7-DHC with high sensitivity. In addition, the modified electrode has the characteristics of excellent anti-interference ability and stability, and been successfully used in the real samples determination, which provides a promising method for the sensitive detection of drug molecules.

Polymer/graphene nanofoam nanocomposites: Properties and potential

Graphene is a nano-allotrope of carbon. It is a two dimensional (2D) one atom thick single layer of sp2 hybridized carbon atoms. An important form of graphene is the three dimensional (3D) graphene, also known as graphene nanofoam. This review article précises progress in the field of 3D graphene-based polymeric nanocomposites. The 3D macroscopic graphene nanostructures when used to reinforce polymer matrices attain superior structural and physical properties. This article considers the design, fabrication, characteristics, and promising applications of polymer/graphene nanofoam nanocomposites. The graphene nanofoam and polymer/graphene nanofoam nanocomposites have been prepared through advance approaches. The microstructure, electrical conductivity, specific capacitance, radiation shielding, mechanical properties, and other physical properties of the polymer/graphene nanofoam architectures have been studied. Interactions between the polymers and 3D graphene architecture are essential to enhance the nanocomposite performance. Polymer/graphene nanofoam nanocomposites applications are for solar cells, fuel cells, supercapacitors, and electromagnetic interference (EMI) shielding.

Exploring the Biosynthetic Potential of TsrM, a B12 -dependent Radical SAM Methyltransferase Catalyzing Non-radical Reactions.

B12 -dependent radical SAM enzymes are an emerging enzyme family with approximately 200,000 proteins. These enzymes have been shown to catalyze chemically challenging reactions such as methyl transfer to sp2- and sp3-hybridized carbon atoms. However, to date we have little information regarding their complex mechanisms and their biosynthetic potential. Here we show, using X-ray absorption spectroscopy, mutagenesis and synthetic probes that the vitamin B12 -dependent radical SAM enzyme TsrM catalyzes not only C- but also N-methyl transfer reactions further expanding its synthetic versatility. We also demonstrate that TsrM has the unique ability to directly transfer a methyl group to the benzyl core of tryptophan, including the least reactive position C4. Collectively, our study supports that TsrM catalyzes non-radical reactions and establishes the usefulness of radical SAM enzymes for novel biosynthetic schemes including serial alkylation reactions at particularly inert C-H bonds.

Identification of potent aldose reductase inhibitors as antidiabetic (Anti-hyperglycemic) agents using QSAR based virtual Screening, molecular Docking, MD simulation and MMGBSA approaches

The aldose reductase (AR) enzyme is an important target enzyme in the development of therapeutics against hyperglycaemia induced health complications such as retinopathy, etc. In the present study, a quantitative structure activity relationship (QSAR) evaluation of a dataset of 226 reported AR inhibitor (ARi) molecules is performed using a genetic algorithm – multi linear regression (GA-MLR) technique. Multi-criteria decision making (MCDM) analysis furnished two five variables based QSAR models with acceptably high performance reflected in various statistical parameters such as, R2 = 0.79–0.80, Q2LOO = 0.78–0.79, Q2LMO = 0.78–0.79. The QSAR model analysis revealed some of the molecular features that play crucial role in deciding inhibitory potency of the molecule against AR such as; hydrophobic Nitrogen within 2 Å of the center of mass of the molecule, non-ring Carbon separated by three and four bonds from hydrogen bond donor atoms, number of sp2 hybridized Oxygen separated by four bonds from sp2 hybridized Carbon atoms, etc. 14 in silico generated hits, using a compound 18 (a most potent ARi from present dataset with pIC50 = 8.04 M) as a template, on QSAR based virtual screening (QSAR-VS) furnished a scaffold 5 with better ARi activity (pIC50 = 8.05 M) than template compound 18. Furthermore, molecular docking of compound 18 (Docking Score = –7.91 kcal/mol) and scaffold 5 (Docking Score = –8.08 kcal/mol) against AR, divulged that they both occupy the specific pocket(s) in AR receptor binding sites through hydrogen bonding and hydrophobic interactions. Molecular dynamic simulation (MDS) and MMGBSA studies right back the docking results by revealing the fact that binding site residues interact with scaffold 5 and compound 18 to produce a stable complex similar to co-crystallized ligand's conformation. The QSAR analysis, molecular docking, and MDS results are all in agreement and complementary. QSAR-VS successfully identified a more potent novel ARi and can be used in the development of therapeutic agents to treat diabetes.

On-Surface Debromination of C6Br6: C6 Ring versus C6 Chain

Carbon allotropes comprising sp-hybridized carbon atoms have been investigated for decades for their molecular structure. One of the unsolved mysteries is whether they should take a linear or cyclic configuration in condensed phases due to the lack of atomistic characterizations. Herein, we designed a molecule with a C6 skeleton as a model system to address this issue, which was achieved by eliminating Br atoms from hexabromobenzene (C6Br6) molecule on the Ag(111) substrate via thermal treatment. It is found that the C6 ring intermediate resulting from complete debromination is energetically unstable at room temperature based on theoretical calculations. It subsequently transforms into the C6 polyynic chain via a ring-opening process and ultimately polymerizes into the organometallic polyyne, whose triyne structural unit is revealed by bond-resolved noncontact atomic force microscopy. Theoretical calculations demonstrated an energetically favorable pathway in which the ring-opening process occurs after complete debromination of C6Br6. Our study provides a platform for the synthesis of elusive carbon-rich materials.

SP3 Hybridized Carbon Atom Dependent Redox Activity and Charge Storage of Quinonoid Main Chain Polymers

Uncontrolled stereochemical flipping of the substituents indirectly affects the redox chemistry of benzoquinone. With this assumption, herein we prepared three different polymers, quinone rings directly bonded (DHBP), quinone rings boned through a methylene bridge (DHB), and phenyl rings substituted methylene bridge (DADC). The substitution of phenyl ring generates the stereo-centered sp3 hybridized carbon center which inhibits ring flipping and uncontrolled stereochemistry. It also affects the electrochemical properties and charge storage ability of the polymer. The polymer with a stereo-centered carbon center (DADC) exhibited 245.4 mAhg−1 specific capacity at 100 mAg−1 current density in an aqueous zinc ion battery. It is far better than the polymers without the stereo-centered polymer, even it is better than the reported quinone cathodes. The outperformance in the charge storage ability was explained in detail based on the stabilization of quinonoid radicals and/or quinonoid anions by the stereochemically restricted carbon center with a bulky phenyl group. The cycling stability was evaluated in galvanostatic charging/discharging over 3000 cycles at 100 mAg−1 current density. The specific capacity was found to be 250.1 mAhg−1 with 91.2% capacity retention and 89.6% coulombic efficiency suggesting the importance of stereo-centered carbon in designing new redox-active organic molecules for energy storage applications.

Carbon-Centered Hydrogen Bonds in Proteins.

Hydrogen bonding (H-bonding) without lone pair(s) of electrons and π-electrons is a concept developed 2-3 years ago. H-bonds involving less electronegative tetrahedral carbon are beyond the classical concept of H-bonds. Herein, we present the first report on H-bonds with tetravalent carbons in proteins. A special bonding arrangement is needed to increase the negative charge density around the sp3-hybridized carbon atom. Therefore, less electronegative elements such as As and Mg, when bonded to sp3-C, enable the C-atoms as H-bond acceptors. Careful protein structure analysis aided by several quantum chemical calculations suggests that these H-bonds are weak to moderate in strength. We developed an empirical equation to estimate the C-H···C H-bond energy in proteins from the distances between the C- and H-atoms. In proteins, the binding energies range from -5.4 to -14.0 kJ/mol. The C-H···C H-bonds assist the substrate binding in proteins. We also explored the potential role of these carbon-centered H-bonds in C-H bond activation through σ-bond metathesis. To our surprise, contribution from these H-bonds is almost of similar magnitude as that from C-H···π H-bonds for C-H bond activation.

Recyclable Copper-Catalyzed Decarboxylative C–C Coupling of the sp3-Hybridized Carbon Atoms of α-Amino Acids

Recyclable Copper-Catalyzed Decarboxylative C–C Coupling of the sp3-Hybridized Carbon Atoms of α-Amino Acids

Sp-hybridized carbon atoms formed by low-energy collisions in carbon nanofoams produced by pulsed laser deposition

The appearance of an sp-hybridization signal has previously been reported in Surface-Enhanced Raman spectra of carbon nanofoams prepared by pulsed laser deposition (PLD). The details of the mechanism for the formation of the sp-hybridized carbon atoms need still further clarification. For a better understanding we have studied two samples produced by PLD in the same experimental run by placing one substrate in front of the plasma plume and a second one beside the graphite target. In this configuration the gas pressure is the same at both sites but the collision energies between the formed nanoparticles are very different. Our present results from Surface Enhanced Raman Spectroscopy and High-Resolution Transmission Electron Microscopy lead us to propose that the sp signal comes mostly from short carbon atom chains formed between carbon nanoparticles due to relatively low-energy collisions at deposition.

Rare-earth modified amorphous carbon films: Effects of erbium and gadolinium on the structural evolution and mechanical properties

Modifying amorphous carbon (a-C) with rare-earth elements is a highly auspicious concept to synthetize functional films with unique characteristics. Among the rare earth elements, Er and Gd demonstrate abundant physicochemical properties and, hence, are of remarkable interest for the element modification of a-C films. Therefore, Er-containing a-C:Er and Gd-containing a-C:Gd films are prepared in a reactive-free magnetron sputtering process. The a-C:Er and a-C:Gd films have an amount of up to 5 at.-% Er and 4.8 at.-% Gd.High-resolution x-ray photoelectron spectroscopy analyses show the formation of ErC and GdC components, which rise proportionally with increasing amount of the rare-earth element. The addition of Er and Gd lowers the sp3 content of C bonds. At the highest concentrations of the respective rare-earth elements, the a-C:Er and a-C:Gd films exhibit a reduced sp3 content of 8%. The number and size of sp2‑carbon clusters in the amorphous network are enhanced with increasing amount of Er and Gd which is evaluated by Raman scattering measurements. X-ray diffraction analyses reveal Er and Gd carbide phases, indicating the formation of a nanocomposite structure consisting of carbidic nanocrystallites and an a-C network. In nanoindentation tests, the non-modified a-C demonstrates a hardness of (21.7 ± 1.6) GPa and an elastic modulus of (232 ± 10) GPa. With increasing Er and Gd contents, the hardness linearly decreases to (16.7 ± 0.9) GPa and (14.8 ± 0.9) GPa, respectively. An analogous behavior is also identified for the elastic modulus. The reduced hardness and elastic modulus are attributed to the lower sp3 content and the larger number and size of the sp2-hybridized carbon atoms. Additionally, the adhesion was slightly improved by the addition of Er and Gd in comparison to non-modified a-C.

Direct chemical synthesis of nitrogen-doped graphynes with high supercapacitance via a cross-coupling copolymerization strategy

Development of graphyne-type carbon materials, which are constructed by different combination of sp2 and sp hybridized carbon atoms, has been a thriving research hotspot in material science, due to their promising application in a range of energy and environmental fields. Herein, nitrogen-doped graphyne materials (NGY-1 and NGY-2) were directly synthesized by Sonogashira-Hagihara cross-coupling reaction, using hydrogen-deficient multi-acetylene and polyhalide compounds as the comonomers. NGY-1 and NGY-2 possess two-dimensional porous structure, high nitrogen content and homogenous nitrogen distribution. After heat-treatment at the temperature of 800 °C, the obtained materials NGY-1–800 and NGY-2–800 demonstrate high supercapacitive energy storage performances with specific capacitances up to 312 F g−1 at 0.1 A g−1 and excellent cycling properties. Compared with NGY-1–800, NGY-2–800 obtained from the pyrazine-containing precursor, exhibits a better rate capability thanks to higher content of graphitic nitrogen doping. The copolymerization strategy developed here can potentially provide a rational design principle and open a new gateway for the construction of novel graphyne-type carbon materials for energy storage applications.

A minimal cage of a diamond twin with chirality

A network of tetrahedral vertices can fill three-dimensional (3D) spaces in a beautiful and isotropic manner, which is found as diamonds with sp3-hybridized carbon atoms. Although a network of trigonal vertices (i.e., another form of carbon atoms with sp2-hybridization) naturally results in a lower-dimensional two-dimensional network of graphenes, an isotropic 3D arrangement of trigonal vertices has been of theoretical and mathematical interest, which has materialized as a proposal of a "diamond twin." We herein report the synthesis and optical resolution of a minimal cage of a chiral diamond-twin network. With triangular phenine units at 14 vertices, triply fused decagonal rings were assembled by forming 15 biaryl edges via coupling. A unique chirality of the network has been disclosed with the minimal cage, which may stimulate explorations of chiral carbonaceous materials.

Shape memory polymer/graphene nanocomposites: State-of-the-art

Abstract Graphene is one of most exceptional type of nanocarbon. It is a two-dimensional, one atom thick, nanosheet of sp2 hybridized carbon atoms. Graphene has been employed as nanofiller for shape memory polymeric nanocomposites due to outstanding electrical conductivity, mechanical strength, flexibility, and thermal stability characteristics. Consequently, graphene nanostructures have been reinforced in the polymer matrices to attain superior structural, physical, and shape recovery properties. This review basically addresses the important class of shape memory polymer (SMP)/graphene nanocomposites. This assessment is revolutionary to portray the scientific development and advancement in the field of polymer and graphene-based shape memory nanocomposites. In SMP/graphene nanocomposites, polymer shape has been fixed at above transition temperature and then converted to memorized shape through desired external stimuli. Presence of graphene has caused fast switching of temporary shape to original shape in polymer/graphene nanocomposites. In this regard, better graphene dispersion, interactions between matrix-nanofiller, and well-matched interface formation leading to high performance stimuli-responsive graphene derived nanocomposites, have been described. Incidentally, the fabrication, properties, actuation ways, and relevance of the SMP/graphene nanocomposite have been discussed here. The potential applications of these materials have been perceived for the aerospace/automotive components, self-healing nanocomposites, textiles, civil engineering, and biomaterials.

Manufacturing high-density graphene edges with electrochemical etching for sensing aminophenol

In this study, an electrochemical etching method were proposed to manufacture high-density graphene edges on the surface of N-doped graphene sheets embedded carbon (N-GSEC) films for sensing aminophenol. We found that the sp3-hybridized carbon and nitrogen atoms were more susceptible to be etched than the sp2-hybridized atoms, resulting in the decrease of amorphous and the formation of more graphene edges. These graphene edges with higher electronic density of states can be served as electrochemical active sites and accelerate the electron transfer rate. The etched N-GSEC film exhibited much better electrochemical activity for two redox probes of Fe(CN)64-/3- and Fe2+/3+ as well as the aminophenol molecules. It can be applied in simultaneous detecting the 4-aminophenol and acetaminophen in the liner concentration ranges of 0.1 μM–250 μM and 0.05 μM–100 μM with detection limit of 0.01 μM and 0.025 μM, respectively. The electrochemical etching of N-GSEC film opened a new avenue for manufacturing a surface with high-density graphene edges in electrochemical sensing.

Anhydride-Terminated Solid-State Carbon Dots with Bright Orange Emission Induced by Weak Excitonic Electronic Coupling.

In this work, fluorescent solid carbon dots (CDs) welcome a new member, namely anhydride-terminated CDs, which have a photoluminescence quantum yield (PLQY) of 28% for orange-emitted CDs at 580 nm in powder form. For the first time, we revealed that the electronic coupling of the functional groups should be a crucial factor affecting the optical properties of solid CDs. Due to the negligible hydrogen bonding interaction between the anhydride groups, the electronic coupling of excitons between neighboring anhydride groups is weak, leading to a high PLQY of 28% and an immobile emission peak at 580 nm in solid state. Anhydride-terminated CDs can be partly converted into carboxyl-terminated CDs after dispersion in ethanol. However, the strong electronic coupling of carboxyl groups at high concentration generates the stacking mode of J-aggregates, giving rise to a red-shifted emission from 450 to 515 nm as well as quenched fluorescence in solid state. In comparison, a useful blue emission for solid-state CDs occurs from low sp2 hybridized carbon atoms, which possess weak electronic coupling and a stationary emission band at 450 nm in both solution and solid state. By adjusting the feed ratio of the reactants, the relevant intensities between the emission from low sp2 hybridized carbon atoms at 450 nm and the emission from anhydride groups at 580 nm can be controlled. As a result, single-component anhydride-terminated CD powder with tunable emission color from orange to white light can be achieved. As-prepared anhydride-terminated CDs can be used for fabricating light-emitting diodes (LEDs), white LEDs, and luminescent solar concentrators (LSCs).

Graphene as a Surface Enhancement Raman Scattering (SERS) Substrate

The discovery of surface-enhanced Raman spectroscopy (SERS) presents an opportunity for the development of ultrasensitive biosensors. SERS allows for fingerprint detection of biomolecules at low concentrations and can perform single-molecule detection. The most used SERS substrates are Plasmonic metal nanostructures such as Au and Ag mainly because of their superior electrical conductivity. The Plasmonic metal nanoparticles enhance the Raman signal of the target biomolecules through the electromagnetic field mechanism. Despite the successful use of metal nanostructures, alternative materials have been sought which can exhibit similar or better properties than their metal counterparts. Materials such as graphene which has excellent electrical properties and high surface area are good candidates for SERS applications. Graphene is a 2D nanomaterial consisting of sp2 hybridized carbon atoms. The use of graphene in SERS is termed graphene-enhanced Raman spectroscopy (GERS) and is reported to use a charge transfer mechanism. Both graphene and metal nanostructures can be used together as SERS substrate and the synergistic effect of their mechanism can improve the enhancement factor and the sensitivity of the biosensor, however, the use of graphene as a SERS substrate is still at an early stage. GERS can be applied in disease diagnosis, detection of food additives, and biological species biosensors. The use of GERS in biosensors such as glucose biosensors presents an opportunity for ultrasensitive biosensors which can greatly improve the lives of individuals living with diabetes. In this review insights will be given on how to successfully circumvent the challenges associated with small Raman cross-section of glucose detection for use in medical application.