Donglai Peng

DNA Immobilization/Hybridization on Plasma-Polymerized Pyrrole

The present work describes the fabrication and characterization of the conducting polymer coatings prepared by the continuous wave plasma polymerization and the applications as adhesion layers for studying DNA immobilization/hybridization. The stability of plasma polymerized pyrrole (ppPY) in the aqueous solution was characterized by ellipsometry. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to investigate polymer matrix properties and oligonucleotide/DNA binding interaction. The successful DNA immobilization on ppPY surfaces was found to depend on the macromolecular architecture of plasma polymerized films. The plasma polymers with similar thickness deposited at different input powers showed various comparable immobilization properties. The plasma-polymerized films prepared at the low input power showed a lower sensitivity toward DNA binding than those films deposited at the high input power. This result will be important to study plasma polymerized films as potential DNA biosensors in the future.

Carbon-based nanocomposites with aptamer-templated silver nanoclusters for the highly sensitive and selective detection of platelet-derived growth factor

We synthesized two kinds of carbon-based nanocomposites of silver nanoclusters (AgNCs). An aptamer for targeted platelet-derived growth factor-BB (PDGF-BB) detection was used as the organic phase to produce AgNCs@Apt, three dimensional reduced graphene oxide@AgNCs@Aptamer (3D-rGO@AgNCs@Apt), and graphene quantum dots@AgNCs@Aptamer (GQD@AgNCs@Apt) nanocomposites. The formation mechanism of the developed nanocomposites was described by detailed characterizations of their chemical and crystal structures. Subsequently, the as-synthesized nanoclusters containing aptamer strands were applied as the sensitive layers to fabricate a novel electrochemical aptasensor for the detection of PDGF-BB, which may be directly used to determine the target protein. Electrochemical impedance spectra showed that the developed 3D-rGO@AgNCs@Apt-based biosensor exhibited the highest sensitivity for PDGF-BB detection among three kinds of fabricated aptasensors, with an extremely low detection limit of 0.82pgmL-1. In addition, the 3D-rGO@AgNCs@Apt-based biosensor showed high selectivity, stability, and applicability for the detection of PDGF-BB. This finding indicated that the AgNC-based nanocomposites prepared by a one-step method could be used as an electrochemical biosensor for various detection procedures in the biomedical field.

An electrochemical sensor based on rhodamine B hydrazide-immobilized graphene oxide for highly sensitive and selective detection of Cu(II)

A novel strategy for fabricating a Cu2+ sensor based on rhodamine B hydrazide (RBH)-immobilized graphene oxide (GO) was reported. The thiol-modified Au electrode was functionalized by carboxyl functionalized GO through intermolecular interactions, followed by chemical bonding with RBH. The developed nanocomposite was used as an electrochemical sensor for detecting Cu2+ in aqueous solution using electrochemical impedance spectroscopy analysis with a detection limit of 0.061 nM within the range from 0.1 to 50 nM. Furthermore, the interference from potentially interfering ions such as Hg2+, Ag+, Cr2+, Fe2+, Pb2+, Ba2+, Mn2+, Co2+, and Ni2+ associated with Cu2+ analysis could be effectively inhibited. In addition, the developed Cu2+ sensor could be reproduced up to 10 cycles. In this approach, the fluorescent probe RBH can be replaced by other fluorescein derivatives which could identify the corresponding ions, which makes the approach a widely applicable strategy for metal ion detection.

Feasible electrochemical biosensor based on plasma polymerization-assisted composite of polyacrylic acid and hollow TiO2 spheres for sensitively detecting lysozyme

A composite made of polyacrylic acid and hollow TiO2 spheres (TiO2@PPAA) was prepared by the plasma polymerization method and subsequently used as an electrode material for detecting lysozyme. The chemical structure, surface morphology, and electrochemical performance of the TiO2@PPAA composite were mainly affected by the plasma input power used during plasma polymerization. After optimizing plasma conditions, aptamer strands exhibited high adsorption affinity toward the surface of TiO2@PPAA composite via synergistic effects between TiO2 and PPAA. Electrochemical impedance spectroscopy results showed that the developed TiO2@PPAA aptasensor presents highly sensitive detection ability toward lysozyme; the limit of detection of the proposed aptasensor is 0.015 ng mL(-1) (1.04 pM) within the range of 0.05-100 ng mL(-1) in terms of 3σ value. The film further showed excellent selectivity toward lysozyme in the presence of interfering proteins, such as thrombin, bovine serum albumin, and immunoglobulin E. Thus, this aptasensing strategy might broaden the applications of plasma polymerized nanomaterials in the field of biomedical research and early clinical diagnosis.

Protein-templated cobaltous phosphate nanocomposites for the highly sensitive and selective detection of platelet-derived growth factor-BB.

We synthesized novel Co3(PO4)2-based nanocomposites with 3D porous architectures via self-assembly; here, bovine serum albumin (BSA) and aptamer were used as organic phases to produce Co3(PO4)2@BSA and Co3(PO4)2@Apt nanocomposites, respectively. The formation mechanism of Co3(PO4)2-based nanocomposites was described based on characterizations of their physio-chemical performance, and the developed nanocomposites were applied as scaffold materials to construct a novel electrochemical aptasensor and detect platelet-derived growth factor-BB (PDGF-BB). The PDGF-BB targeting aptamer must be immobilized onto the Co3(PO4)2@BSA-modified electrode to detect PDGF-BB, whereas Co3(PO4)2@Apt-based aptasensor may be directly used to determine the target protein. Electrochemical impedance spectroscopy results showed that the developed Co3(PO4)2@BSA- and Co3(PO4)2@Apt-based aptasensors present highly sensitive detection ability toward PDGF-BB. Due to the special nanoflower structure, the Co3(PO4)2@BSA-based aptasensor features a detection limit of 3.7 pg mL(-1); while the limit of detection of the Co3(PO4)2@Apt-based aptasensor is 61.5 pg mL(-1), which is the possible bioactivity loss of the aptamer in Co3(PO4)2@Apt nanocomposite. The two detection limits obtained are still much lower than or comparable with those of previously reported aptasensors. The Co3(PO4)2@BSA- and Co3(PO4)2@Apt-based aptasensors showed high selectivity, stability, and applicability for detecting the desired protein. This finding indicates that the Co3(PO4)2-based nanocomposites could be used as an electrochemical biosensor for various detection procedures in the biomedical field.

Plasma polyacrylic acid and hollow TiO2 spheres modified with rhodamine B for sensitive electrochemical sensing Cu(II)

We report a novel nanocomposite of hollow TiO2 microspheres and plasma polyacrylic acid (TiO2@PPAA) modified with rhodamine B (TiO2@PPAA-RhB). This nanocomposite was further used as an electrochemical sensor for the ultra-sensitive and selective detection of Cu2+ in water. A gold electrode was modified with hollow TiO2 nanospheres, followed by the closely bonded layer of PPAA via plasma polymerization. Subsequently, the carboxyl groups of TiO2@PPAA nanocomposites were activated to ester groups by N-hydroxysuccinimide/1-ethyl-3-(3-dimethylaminoprolyl) carbodiimide hydrochloride. The resultant activated ester groups reacted with the amino groups on rhodamine to form the amide groups, leading to the modification of TiO2@PPAA nanocomposites with rhodamine. Considering the synergistic effect of strong electrostatic interaction between the carboxyl groups of PPAA and Cu2+, the direct adsorption of Cu2+ on the TiO2 surface, and the coordination chemistry formed between Cu2+ and rhodamine, the developed electrochemical biosensor exhibited high sensitivity of Cu2+ detection, with a detection limit of 0.404 pM within the range of 0.001–10 nM of Cu2+. Therefore, the fabricated electrochemical sensor based on TiO2@PPAA-RhB can be obtained via plasma polymerization and represents a highly promising tool for use in environmental monitoring.

Electrochemical sensor based on a polyaniline-modified SnO2 nanocomposite for detecting ethephon

Ethephon is a plant growth regulator and is often applied in the process of fruit growth. It could result in considerable inhibition of cholinesterase in blood plasma and erythrocytes and is very harmful to human beings on excessive consumption. Nanocomposites from polyaniline and stannic oxide (SnO2@PANI) were synthesized and developed as the electrode material for detecting ethephon. Herein, SnO2 nanoparticles were prepared by the method of liquid phase precipitation. Afterwards, the as-prepared SnO2 nanoparticles were mixed with the aniline polymerization system to form the SnO2@PANI nanocomposite. The basic chemical components of the fabricated sensor were characterized in detail using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. It was demonstrated that the developed SnO2@PANI nanocomposite exhibits good electrochemical performance with relatively low charge-transfer resistance. Compared with the pristine SnO2 and PANI, ethephon preferred to adsorb onto the SnO2@PANI nanocomposite surface because of the synergic interaction between the two components of SnO2 and PANI. The electrochemical impedance spectra illustrated that the fabricated ethephon sensor had excellent sensitivity, with a detection limit of 4.76 pg mL−1 within the range from 0.01 to 5 ng mL−1. Moreover, the developed electrochemical biosensor exhibits good selectivity and stability. All of these good performances provide a promising tool to detect illegal food additives.

Aptasensor Based on Hierarchical Core–Shell Nanocomposites of Zirconium Hexacyanoferrate Nanoparticles and Mesoporous mFe3O4@mC: Electrochemical Quantitation of Epithelial Tumor Marker Mucin-1

A novel nanostructured hierarchical core–shell nanocomposite of zirconium hexacyanoferrate (ZrHCF) and a mesoporous nanomaterial composed of Fe3O4 and carbon nanospheres (denoted as ZrHCF@mFe3O4@mC) was prepared and used as a novel platform for an aptasensor to detect the epithelial tumor marker mucin-1 (MUC1) sensitively and selectively. The prepared ZrHCF@mFe3O4@mC nanocomposite exhibited good chemical functionality, water stability, and high specific surface area. Therefore, large amounts of aptamer molecules resulted in high sensitivity of the developed electrochemical aptasensor toward traces of MUC1. The constructed sensor also showed a good linear relationship with the logarithm of MUC1 concentration in the broad range of 0.01 ng·mL–1 to 1.0 μg·mL–1, with a low detection limit of 0.90 pg·mL–1. The fabricated ZrHCF@mFe3O4@mC-based aptasensor exhibited not only high selectivity because of the formation of aptamer–MUC1 complex but also good stability, acceptable reproducibility, and applicability. The proposed novel strategy based on a newly prepared hierarchical core–shell nanocomposite demonstrated outstanding biosensing performance and presents potential applications in biomedical fields.

Chemical structure of hollow carbon spheres and polyaniline nanocomposite

In this data article, the chemical data of hollow carbon spheres and polyaniline (HCS@PANI) nanocomposite are presented for the research article entitled “Novel electrochemical biosensor based on core-shell nanostructured composite of hollow carbon spheres and polyaniline for sensitively detecting malathion” (He et al., 2018) [1]. The data includes chemical structure and components obtained by Raman spectra, X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption and desorption isotherms.