Polymers-Based Biosensors

Dear Colleagues,

The design and development of biosensing platforms and devices involve a large range of synthesis strategies, such as, for example, chemical or electrochemical polymerization, pre- or post-synthetic functionalization, molecularly imprinting, metal–organic frameworks, block copolymer templating, molecular or block-assembling bottom-up processes, and even creating molecular and supramolecular hybrid organic–inorganic interfaces.

A great variety of polymer-based biosensors were reported in the literature in the last decade, referring to particular polymers such as polyethyleneimine, polyaniline, PEDOT or polypyrrole, and derivatives obtained either by electropolymerization or by chemical polymerization, combined with nanomaterials such as CNTs, graphene, or gold nanoparticles. Electropolymerization in deep eutectic solvents is another interesting approach, the polymers obtained in deep eutectic solvents (DES), exhibit improved features compared with the same polymers obtained in aqueous solutions.

One of the most important aspects in biosensors development is the immobilization platform which needs to ensure a high stability for the molecular biorecognition compound and to maintain its activity as long as possible. The entrapment in a polymeric matrix or the employment of a particularly functionalized polymeric film (with amino or carboxyl groups, azide groups for click chemistry, biotine, avidine, or cyclodextrine) is one of the most important immobilization methods for the molecular recognition element in biosensor design. Natural receptors (enzyme, antibody, DNA, RNA, peptide, etc.) and biomimetic receptors (ligands like crown ethers or cryptands, cyclodextrins, or calixarenes) immobilization with polymers is one of the most challenging topics.

Nanoparticle-polymer composites are advanced functional materials, with nanoparticles integrated into a polymer matrix. In addition to the characteristics of polymers, nanocomposites may acquire the outstanding electrical, optical, and magnetic properties of their metal components. Optical nonlinearities and/or infra-low/ultra-high refractive indices suitable for ultrathin color filters, UV absorbers, optical sensors, waveguides, optical strain detectors, and thermo-chromic materials, are only some of the potential applications of nanocomposites. Because of the strong Au and Ag localized surface plasmon resonance (LSPR) bands in the visible spectrum, giving rise to characteristic absorption and strong field confinement and enhancement, some gold nanocomposites are particularly appropriate for sensing applications. LSPR has been extensively exploited for sensing and biosensing, with enormous progress in recent years, both in terms of instrumentation and applications. Gold is the most promising candidate due to its strong scattering length, bio-conjugation, and long-term stability, which is essential for a stable and sensitive biosensing platform. The bio-sensing properties of nano-composites depend on the conditions of their preparation that are pivotal for the distribution of the metal particles in the polymer matrix. Nanocomposites can be synthesized through different approaches, principally, either by in-situ methods, or by incorporating pre-made nanoparticles into a polymer matrix, by using a common solvent (ex-situ). In addition, physical methods such as chemical vapor deposition, ion implantation, and thermolysis have been successfully used. In spite of the efforts to achieve nanocomposites with appropriate morphologies and enhanced surface properties, the control of nanoparticles spatial distribution still remains at an emerging stage.

The Special Issue aims to highlight not only the most recent advances and challenges but also the future trends and perspectives in the polymer-based biosensor field. Papers on the fabrication protocols, the characterization methods of the resulting nanocomposite films, and their applications are all welcome. Reviews and original research papers are all welcome.

Dr. Simona Badilescu
Prof. Dr. Robert Sandulescu
Guest Editors

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• Polypyrrole and derivatives
• Electropolymerization vs chemical polymerization
• Electropolymerization in deep eutectic solvents
• Natural and biomimetic receptors immobilization with polymers
• Nanosized and nanostructured polymers
• Molecularly imprinted polymers (MIPs)
• Metal-organic polymer matrix (MOFs)
• Smart polymers for biosensors

• Nanoplasmonics and microfluidics
• Surface Plasmon Resonance sensors based on polymer optical fibers
• Microfiber optical sensors
• Nanoparticle-stimuli responsive polymer multilayer assemblies for sensing applications