In this paper, an aqueous solution diffusion-localized platform (ASDLP) for multianalyte immunogold staining assays has been developed for the first time by assembling nitrocellulose (NC) strips onto a superhydrophobic polycarbonate (PC) coating with a water contact angle (CA) up to 160°. In the concept-of-proof experiments, the ASDLP was used for colorimetric detection of a human IgG model antigen based on the gold-enhanced gold nanoparticle (AuNP) label amplification. The relative concentration of the analyte captured on NC was further quantified by measuring the intensity of staining result with the use of image analysis software. The comparison study demonstrates that the white superhydrophobic PC-based ASDLP can offer preferable advantages over the commonly adopted bulky piece of NC for immunogold staining assays, in terms of the localized antibody immobilization and reagent addition, the minimization of “coffee effect”, uniformity of staining results, quantitative analysis and use efficiency of NC. Moreover, the high selectivity of a multiple antibodies-immobilized NC strip array for multiple antigens in a single sample has been further demonstrated in the multianalyte immunogold staining assay experiments.

Encoded polymer films for electrochemical identification have been achieved by embedding different semiconductor nanocrystals into self-polymerized dopamine films. Such encoded polydopamine films based on mussel-inspired surface chemistry show high adhesive ability and can be created on a wide range of inorganic and organic materials, including noble metals, oxides, ceramics, and synthetic polymers. By incorporating different predetermined levels of various redox nanomarkers, the use of multi-film system composed of multiple, sequenced polydopamine identification films could theoretically generate nearly unlimited (>1012) distinct voltammetric signatures (electric codes).

A novel immobilization platform has been developed for fabricating enzyme-based biosensors of direct electrochemistry by synergistically using ZnO crystals and nano-sized gold particles (Nanogold). ZnO crystals were synthesized with flower-like structure to be casted on the electrode mediated by chitosan so as to provide larger surface area for anchoring horseradish peroxidase (HRP)-labeled Nanogold. The resultant enzyme biosensor was tested for the determination of H2O2 as a model of test system. Experimental results showed that HRP could be immobilized onto the nanocomposite matrix with high loading amount and well-retained bioactivity. Moreover, rapid and direct electron transferring could be achieved between the enzyme’s active sites and the electrode surface, thus facilitating the direct electroanalysis of H2O2. The developed enzyme sensor can directly determine H2O2 in the concentration range from 1.5 × 10−6 to 4.5 × 10−4 M, with a detection limit of 7.0 × 10−7 M. High detection reproducibility can be additionally expected. Such an enzyme immobilization platform of ZnO–Chitosan/Nanogold should hold great promise for the development of the enzyme biosensors of direct electrochemistry.

A renewable, site-selective immobilization platform of microelectrode array (MEA) for multiplexed immunoassays has been initially developed using pencil graphite particles coated with gold layers as microelectrodes. The graphite particles available on the common pencil were utilized for directing the electro-deposition of gold layers with uniform microstructures which displayed a well-defined sigmoidal voltammetric response. In the concept-of-proof experiments, the resulting MEA platform was modified with functionalized monolayer, on which anti-human IgG antibodies could be stably immobilized in a site-selective way through binding chemistry to selectively capture human IgG antigens from the sample media. The subsequent introduction of anti-human IgG antibodies conjugated with 15 nm electro-active gold nanoparticles to recognize the captured IgG proteins resulted in a significant decrease in the interfacial electron-transfer resistance. High sensitive electrochemical quantification by gold nanoparticle-amplified impedance responses could thus be achieved. Experimental results show that the developed MEA sensor can allow for the detection of human IgG with wide linear range (0.05–100 ng ml−1) and sensitivity over 103 larger than that of the conventional, bulk gold electrode. The rapid regeneration of the used MEA platform can additionally be realized by a simple electrochemical treatment. The high selectivity of four individually addressable MEA platforms for multiple antigens in a single sample has been further demonstrated in the multiplexed immunoassay experiments. Such a site-selective immobilization strategy of MEA platform may open a new door towards the development of various simple, sensitive, cost-effective, and reusable biological sensors and biochips.

A new phase separation methodology has been initially proposed for creating white or colorful super-hydrophobic coatings on the surfaces of various material substrates simply by using a common polymer, i.e., polycarbonate (PC), and its solvent and non-solvents suitably selected. The cleaned substrates were first dipped into the PC polymer solution and then further treated with the PC non-solvent, forming a super-hydrophobic coating at ambient room temperature within ∼21 min. It was found that PC coatings could present various surface morphologies and tunable hydrophobic characteristics if treated with different polymer non-solvents, as characterized in SEM images. The developed protocol can allow the super-hydrophobic coatings to be fabricated without any further surface modifications, showing water contact angles (CAs) of up to 160° and rolling angles of less than 5°. They might well retain super-hydrophobicity over the whole pH range and have long-term mechanic stability. Colorful super-hydrophobic surfaces could also be produced by doping different oily paints or dyes into the PC matrixes. Such a fabrication methodology may be extended to a wide variety of polymers, which may open up new avenues for creating super-hydrophobic coatings on various material substrates especially those with intricate shapes (i.e., channels) in industrial and biological processes.

An integrated piezoelectric immunosensor array has been developed to immunophenotype acute leukemias in clinic. Each quartz crystal microbalance (QCM) was fabricated with plasma-polymerized film of n-butylamine, nanogold particles, and protein A (PA) to be used to immobilize antibodies in orientation. Leukemic lineage-associated monoclonal antibodies were separately immobilized onto the nanogold–PA-modified surface of the crystals, which were constructed by a 2 × 2 type of probes forming a QCM-based immunosensor array. The main detection conditions were investigated, including the immobilization amount of antibodies, pH, immunoreaction time, sample dilution ratio, etc. The immunophenotyping feasibility of the new technique was investigated through simultaneously analyzing Jurkat cells by the immunosensor array method, immunohistochemistry, and flow cytometry. It was found that the developed technique could readily identify leukemia samples in 5 min and might monitor dynamically the immunoreaction processes. Moreover, comparison studies were carried out for CD antigens expressed on the nucleated cells isolated from 96 acute leukemic patients and 24 normal subjects using the QCM-based immunosensor method and the fluoroimmunoassay. Results obtained by immunophenotyping patients’ samples with the immunosensor-based method achieved the rate of 88.93% in 768 groups of numerical data, where no significant statistical difference was observed between the two methods when checked by χ2 analysis (χ2 = 3.4, p > 0.05). This new immunosensor array showed the merits of high sensitivity, high specificity, good reproducibility, easy operation, and low cost. The results of specimen evaluation indicated that it might be clinically suitable for quantifying human differentiated leukocytes and immunophenotyping of acute leukemias.

A new phase separation methodology has been initially proposed for creating white or colorful super-hydrophobic coatings on the surfaces of various material substrates simply by using a common polymer, i.e., polycarbonate (PC), and its solvent and non-solvents suitably selected. The cleaned substrates were first dipped into the PC polymer solution and then further treated with the PC non-solvent, forming a super-hydrophobic coating at ambient room temperature within ∼21 min. It was found that PC coatings could present various surface morphologies and tunable hydrophobic characteristics if treated with different polymer non-solvents, as characterized in SEM images. The developed protocol can allow the super-hydrophobic coatings to be fabricated without any further surface modifications, showing water contact angles (CAs) of up to 160° and rolling angles of less than 5°. They might well retain super-hydrophobicity over the whole pH range and have long-term mechanic stability. Colorful super-hydrophobic surfaces could also be produced by doping different oily paints or dyes into the PC matrixes. Such a fabrication methodology may be extended to a wide variety of polymers, which may open up new avenues for creating super-hydrophobic coatings on various material substrates especially those with intricate shapes (i.e., channels) in industrial and biological processes.