Journal of Materials Chemistry B Editor's choice web collection: ‘‘Seeing the unseen updated: advances in biosensing’’
Xiaogang
Qu
Laboratory of Chemical Biology and State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China. E-mail: xqu@ciac.ac.cn
Abstract
Xiaogang Qu introduces a Journal of Materials Chemistry B Editor's choice web collection on advances in biosensing (http://rsc.li/BiosensorsAdvances).
 Xiaogang Qu |
To date, nanomaterials-based smart biosensing platforms have been successfully designed and used in various fields. When analyzing their working principles, electrical and optical biosensing are still the two main adapted strategies. (1) Electrical biosensing is one of the most popular detection methods of biosensors because it can directly transform certain analytes into quantitative electrical signals for data processing. Electrical biosensing is mainly divided into two categories. One is based on conductance change and the other is electrochemical biosensing. (2) Optical detection techniques, with their advantages of simplicity, convenience and sensitivity, have been widely applied to biosensing. The optical analysis systems cover fluorescence, surface-enhanced Raman scattering (SERS), chemiluminescence, colorimetric assays, electrochemiluminescence (ECL) and surface plasmon resonance (SPR). Electrical or optical detection methods are usually combined with signal amplification strategies to generate novel analysis systems with enhanced sensitivity and selectivity. To meet various requirements, other sensing strategies have also been developed, such as mass spectroscopy (MS), and various microscopies (TEM, SEM, AFM).
In this biosensing collection, a series of representative works have been selected and may be summarized as follows. (1) Detection of ions. Ion sensing takes up a large proportion of research in biosensing because the ionic concentrations drastically impact biological activity and can be an indicator of biological activity. Also, ion sensing is usually used as a lever to detect other biological markers. Inorganic ions, especially heavy metal ions, and H+ (pH detection), CN−, HSO3−, etc., are the main types of analytes. A challenge in this field is how to develop effective platforms to accurately determine different ions at low levels in the complex biological system. (2) Detection of DNA. Sensitive and selective detection of DNA is important for gene therapy, mutation analysis and clinical diagnosis. The basic principle of DNA sensing is based on the highly specific Watson–Crick base-pairing interactions of matched DNA strands. To date, numerous approaches based on different detection techniques have been developed in DNA analysis. A current challenge in DNA sensing is rational design of convenient and inexpensive assays for highly sensitive and selective detection of DNA with rapid and easy manipulation. In addition, DNA molecules possess controllable and polymorphic secondary structures and exhibit robust physicochemical stability, making them promising candidates for constructing a variety of biosensors for other biological analytes. (3) Detection of small molecules. Physiologically important small molecules (glucose, ATP, hydrogen peroxide, radical oxygen species, nitric oxide, uric acid, ascorbic acid, HOCl, glutathione, folic acid, etc.) are other biosensing targets due to their physiological and pathological functions. Some gases are biologically relevant or important physiological markers, such as carbon monoxide (CO), carbon peroxide (CO2) and oxygen (O2); they are also the sensing targets in this field. (4) Detection of enzymes. Due to extremely high biocatalytic activities and specificities, enzymes are extensively employed in bioanalysis as recognition elements and signal amplifiers. Enzyme detection has been becoming a hot area in materials-based biosensing. In current studies, nanomaterials have been widely applied to enhance the sensitivity for detection of enzymatic activity. (5) Detection of cells. Sensitive detection of cells, especially cancer cells, plays a critical role in the early diagnosis of cancer and cancer metastasis. Detection of circulating tumor cells (CTCs) is challenging and rather difficult because CTCs are extremely rare in peripheral blood. Increasing attention has been paid to developing biosensors for quantitative cancer cell sensing and monitoring.
In the last two decades, remarkable achievements have been made in biosensing, as evidenced by the wide applications in various areas, such as healthcare and clinical diagnosis. Although biosensing technology and methods have experienced substantial development, there are still plenty of challenges in biosensing applications. Several points should be taken into account in this field.
(1) Enhancement of sensitivity by signal amplification. Most of the present biosensors exhibit moderate or even weak sensitivity, which would limit their application in ultrasensitive bioanalysis and miniaturized assays. This shortcoming can be addressed by signal amplification, such as DNA amplification, enzyme amplification and nanomaterial-based amplification. How to realize the signal amplification should be a crucial factor in designing future biosensors.
(2) Construction of multi-functional sensing platforms. Even though multi-functional biosensors with the ability of “sensing and treating” or “sensing and imaging” have received considerable attention due to the need for integration of early diagnosis and treatment, it has been still demanding. Rational grafted nanomaterials show excellent properties such as fluorescent, superparamagnetic, electrical and enzyme-like properties. Hybrid multi-functional nanocomposites with abilities of sensing, imaging and treating, can be constructed by reasonably integrating these advantages in one system.
(3) Biosensing in complex systems. Most platforms just work well in aqueous solution or simple buffer conditions, and are not ready for use in complex systems or in practical samples. Much attention should be paid to the development of biosensors for practical applications.
(4) Simplification of biosensing. Present biosensors usually suffer from the drawbacks of complex handling procedures, high cost and professional operation. With the achievements of nanotechnology and nanoscience, nanomaterial-based biosensors hold great promise in realizing simplification due to rapid analysis procedures, simple and inexpensive construction and easy miniaturization.
(5) Exploitation of novel sensing mechanisms. In recent years, several nanomaterials with novel properties have been developed, these should provide opportunities for developing more advanced sensing platforms.
In summary, functional materials-based biosensing has made significant breakthroughs in recent years, and many promising and interesting results have been published in this exciting field. This Editor's choice web collection (http://rsc.li/BiosensorsAdvances) entitled “Seeing the unseen updated: advances in biosensing” highlights Journal of Materials Chemistry B's recent outstanding papers in functional materials-based biosensing. It is the second in a two-part online collection focused on bioimaging and biosensors. Journal of Materials Chemistry B is an interdisciplinary journal, covering all aspects of the production, properties or applications of materials for healthcare and biomedicine, materials at the biointerface, biomimetics and bio-inspired or natural materials.
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