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According to the World Health Organization (WHO), almost 2 billion people each year are infected worldwide with flu-like pathogens including influenza. This is a contagious disease caused by viruses belonging to the family Orthomyxoviridae. Employee absenteeism caused by flu infection costs hundreds of millions of dollars every year. To successfully treat influenza virus infections, detection of the virus during the initial development phase of the infection is critical, when tens to hundreds of virus-associated molecules are present in the patient’s pharynx. In this study, we describe a novel universal diamond biosensor, which enables the specific detection of the virus at ultralow concentrations, even before any clinical symptoms arise. A diamond electrode is surface-functionalized with polyclonal anti-M1 antibodies, which then serve to identify the universal biomarker for the influenza virus, M1 protein. The absorption of the M1 protein onto anti-M1 sites of the electrode change its electrochemical impedance spectra. We achieved a limit of detection of 1 fg/ml in saliva buffer for the M1 biomarker, which corresponds to 5–10 viruses per sample in 5 minutes. Furthermore, the universality of the assay was confirmed by analyzing different strains of influenza A virus.

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We report the novel modification of a hydrogen-terminated polycrystalline boron-doped electrode with a microwave pulsed-plasma polymerized allylamine. Boron-doped diamond (BDD) was coated with a very thin layer of adherent cross-linked, pinhole- and additive-free allylamine plasma polymer (PPAAm) resistant to hydrolysis and delamination and characterized by a high density of positively charged amino groups. The pulsed microwave plasma was applied to improve the cross-linking degree and bonding of the plasma polymeric films to boron-doped diamond. The amine-treated BDD films were assessed by advanced surface analytical techniques, such as X-ray photoelectron spectroscopy (XPS), FT-IR, scanning electron microscopy (SEM), laser-induced fluorescence, and water contact angle measurements. The amine-modified Si/BDD surface was functionalized with selected organic molecules containing a carboxylic group in the presence of coupling agents such as diisopropylcarbodiimide (DIC). The anthraquinone derivatives Boc-Lys(AQ)–OH and peptide anthraquinone derivatives of dendrimers were used as electroactive agents for characterization by cyclic voltammetry (CV). The fluorescence reference standards Rhodamine 110 and Fmoc-Trp(Boc)–OH were selected for fluorescence studies.

In this study, we have demonstrated the fabrication of novel materials called boron-doped carbon nanowalls (B:CNWs), which are characterized by remarkable electrochemical properties such as high standard rate constant (k°), low peak-to-peak separation value (ΔE) for the oxidation and reduction processes of the [Fe(CN)] redox system, and low surface resistivity. The B:CNW samples were deposited by the microwave plasma-assisted chemical vapor deposition (CVD) using a gas mixture of H/CH/BH and N. Growth results in sharp-edged, flat, and long CNWs rich in sp as well as sp hybridized phases. The achieved high values of k° (1.1 × 10 cm s) and ΔE (85 mV) are much lower compared to those of the glassy carbon or undoped CNWs. The enhanced electrochemical performance of the B:CNW electrode facilitates the simultaneous detection of DNA purine bases: adenine and guanine. Both separated oxidation peaks for the independent determination of guanine and adenine were observed by means of cyclic voltammetry or differential pulse voltammetry. It is worth noting that the determined sensitivities and the current densities were about 1 order of magnitude higher than those registered by other electrodes.