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A special issue of Biosensors (ISSN 2079-6374). This special issue belongs to the section "Nano- and Micro-Technologies in Biosensors".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 36650

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Special Issue Editors

Dr. Pengfei Zhang

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Guest Editor

Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing, China
Interests: label-free biosensing and imaging; single-molecule imaging; cell analysis
Special Issues, Collections and Topics in MDPI journals

Dr. Rui Wang

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Guest Editor

School of Biological Science & Medical Engineering, Southeast University, Nanjing, China
Interests: nanocrystal; biosensors; bio-imaging; SERS; TERS
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Label-free biosensors are an indispensable tool for analyzing intrinsic molecular properties, such as mass, and quantifying molecular interactions without interference from labels, which is critical for the screening of drugs, the detection of disease biomarkers and understanding biological processes at the molecular level. Recently developed approaches, including interferometric scattering microscopy, plasmonic scattering microscopy, and evanescent scattering microscopy, have pushed beyond ensemble averages and revealed the statistical distributions of molecular properties and binding processes by providing single-molecule imaging capabilities. These single-molecule imaging techniques pave the road towards understanding molecular interaction processes at a great level of detail. Nonetheless, the demand for developing novel single-molecule label-free sensing schemes that are cost-effective, easy to use, and especially applicable in commercial microscopy or other commercial label-free biosensors is ever increasing. Therefore, this Special Issue, " Label-free Biosensors", focuses on recent advances in the production of highly sensitive label-free biosensors, their applications in the detection and binding kinetics analysis of biological macromolecules such as proteins with a molecular weight larger than 100 kDa, and combination with other technologies for the efficient detection and screening of small molecules such as microRNA. We invite research submissions capable of helping advance the field of label-free biosensors and their applications for the efficient analysis of biomarkers.

With best regards,

Dr. Pengfei Zhang
Dr. Rui Wang
Guest Editors

Manuscript Submission Information

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Keywords

label-free biosensing
molecular interaction
single-molecule detection
imaging
biological macromolecules
proteins
DNA
RNA
biomarkers

Published Papers (12 papers)

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Editorial

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3 pages, 182 KiB

Open AccessEditorial

Label-Free Biosensor

by Pengfei Zhang and Rui Wang

Biosensors 2023, 13(5), 556; https://doi.org/10.3390/bios13050556 - 18 May 2023

Viewed by 1304

Abstract

Label-free biosensors have become an indispensable tool for analyzing intrinsic molecular properties, such as mass, and quantifying molecular interactions without interference from labels, which is critical for the screening of drugs, detecting disease biomarkers, and understanding biological processes at the molecular level [...] [...] Read more.

(This article belongs to the Special Issue Label-Free Biosensor)

Research

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12 pages, 3205 KiB

Open AccessArticle

Label-Free Sequence-Specific Visualization of LAMP Amplified Salmonella via DNA Machine Produces G-Quadruplex DNAzyme

by Huan Zeng, Shuqin Huang, Yunong Chen, Minshi Chen, Kaiyu He, Caili Fu, Qiang Wang, Fang Zhang, Liu Wang and Xiahong Xu

Biosensors 2023, 13(5), 503; https://doi.org/10.3390/bios13050503 - 26 Apr 2023

Cited by 2 | Viewed by 1506

Abstract

Salmonella is one of four key global causes of diarrhea, and in humans, it is generally contracted through the consumption of contaminated food. It is necessary to develop an accurate, simple, and rapid method to monitor Salmonella in the early phase. Herein, we developed a sequence-specific visualization method based on loop-mediated isothermal amplification (LAMP) for the detection of Salmonella in milk. With restriction endonuclease and nicking endonuclease, amplicons were produced into single-stranded triggers, which further promoted the generation of a G-quadruplex by a DNA machine. The G-quadruplex DNAzyme possesses peroxidase-like activity and catalyzes the color development of 2,2′-azino-di-(3-ethylbenzthiazoline sulfonic acid) (ABTS) as the readouts. The feasibility for real samples analysis was also confirmed with Salmonella spiked milk, and the sensitivity was 800 CFU/mL when observed with the naked eye. Using this method, the detection of Salmonella in milk can be completed within 1.5 h. Without the involvement of any sophisticated instrument, this specific colorimetric method can be a useful tool in resource-limited areas. Full article

(This article belongs to the Special Issue Label-Free Biosensor)

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14 pages, 3342 KiB

Open AccessArticle

Electrochemical Immunosensor Using Electroactive Carbon Nanohorns for Signal Amplification for the Rapid Detection of Carcinoembryonic Antigen

by Angélica Domínguez-Aragón, Erasto Armando Zaragoza-Contreras, Gabriela Figueroa-Miranda, Andreas Offenhäusser and Dirk Mayer

Biosensors 2023, 13(1), 63; https://doi.org/10.3390/bios13010063 - 30 Dec 2022

Cited by 3 | Viewed by 1999

Abstract

In this work, a novel sandwich-type electrochemical immunosensor was developed for the quantitative detection of the carcinoembryonic antigen, an important tumor marker in clinical tests. The capture antibodies were immobilized on the surface of a gold disk electrode, while detection antibodies were attached to redox-tagged single-walled carbon nanohorns/thionine/AuNPs. Both types of antibody immobilization were carried out through Au-S bonds using the novel photochemical immobilization technique that ensures control over the orientation of the antibodies. The electroactive SWCNH/Thi/AuNPs nanocomposite worked as a signal tag to carry out both the detection of carcinoembryonic antigen and the amplification of the detection signal. The current response was monitored by differential pulse voltammetry. A clear dependence of the thionine redox peak was observed as a function of the carcinoembryonic antigen concentration. A linear detection range from 0.001–200 ng/mL and a low detection limit of 0.1385 pg/mL were obtained for this immunoassay. The results showed that carbon nanohorns represent a promising matrix for signal amplification in sandwich-type electrochemical immune assays working as a conductive and binding matrix with easy and versatile modification routes to antibody and redox tag immobilization, which possesses great potential for clinical diagnostics of CEA and other biomarkers. Full article

(This article belongs to the Special Issue Label-Free Biosensor)

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9 pages, 2670 KiB

Open AccessArticle

Label-Free Sensing of Biomolecular Adsorption and Desorption Dynamics by Interfacial Second Harmonic Generation

by Chuansheng Xia, Jianli Sun, Qiong Wang, Jinping Chen, Tianjie Wang, Wenxiong Xu, He Zhang, Yuanyuan Li, Jianhua Chang, Zengliang Shi, Chunxiang Xu and Qiannan Cui

Biosensors 2022, 12(11), 1048; https://doi.org/10.3390/bios12111048 - 20 Nov 2022

Cited by 2 | Viewed by 1525

Abstract

Observing interfacial molecular adsorption and desorption dynamics in a label-free manner is fundamentally important for understanding spatiotemporal transports of matter and energy across interfaces. Here, we report a label-free real-time sensing technique utilizing strong optical second harmonic generation of monolayer 2D semiconductors. BSA molecule adsorption and desorption dynamics on the surface of monolayer MoS₂ in liquid environments have been all-optically observed through time-resolved second harmonic generation (SHG) measurements. The proposed SHG detection scheme is not only interface specific but also expected to be widely applicable, which, in principle, undertakes a nanometer-scale spatial resolution across interfaces. Full article

(This article belongs to the Special Issue Label-Free Biosensor)

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12 pages, 3409 KiB

Open AccessArticle

Carbon Dots Conjugated Antibody as an Effective FRET-Based Biosensor for Progesterone Hormone Screening

by Disha, Poonam Kumari, Manoj K. Patel, Parveen Kumar and Manoj K. Nayak

Biosensors 2022, 12(11), 993; https://doi.org/10.3390/bios12110993 - 09 Nov 2022

Cited by 10 | Viewed by 2360

Abstract

In this work, carbon dots (CDs) were synthesized by a one-step hydrothermal method using citric acid and ethylene diamine, and covalently functionalized with antibodies for the sensing of progesterone hormone. The structural and morphological analysis reveals that the synthesized CDs are of average size (diameter 8–10 nm) and the surface functionalities are confirmed by XPS, XRD and FT-IR. Further graphene oxide (GO) is used as a quencher due to the fluorescence resonance energy transfer (FRET) mechanism, whereas the presence of the analyte progesterone turns on the fluorescence because of displacement of GO from the surface of CDs effectively inhibiting FRET efficiency due to the increased distance between donor and acceptor moieties. The linear curve is obtained with different progesterone concentrations with 13.8 nM detection limits (R² = 0.974). The proposed optical method demonstrated high selectivity performance in the presence of structurally resembling interfering compounds. The PL intensity increased linearly with the increased progesterone concentration range (10–900 nM) under the optimal experimental parameters. The developed level-free immunosensor has emerged as a potential platform for simplified progesterone analysis due to the high selectivity performance and good recovery in different samples of spiked water. Full article

(This article belongs to the Special Issue Label-Free Biosensor)

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10 pages, 3023 KiB

Open AccessFeature PaperArticle

A Sensitive Aptamer Fluorescence Anisotropy Sensor for Cd²⁺ Using Affinity-Enhanced Aptamers with Phosphorothioate Modification

by Hao Yu and Qiang Zhao

Biosensors 2022, 12(10), 887; https://doi.org/10.3390/bios12100887 - 17 Oct 2022

Cited by 8 | Viewed by 2079

Abstract

Rapid and sensitive detection of heavy metal cadmium ions (Cd²⁺) is of great significance to food safety and environmental monitoring, as Cd²⁺ contamination and exposure cause serious health risk. In this study we demonstrated an aptamer-based fluorescence anisotropy (FA) sensor for Cd²⁺ with a single tetramethylrhodamine (TMR)-labeled 15-mer Cd²⁺ binding aptamer (CBA15), integrating the strengths of aptamers as affinity recognition elements for preparation, stability, and modification, and the advantages of FA for signaling in terms of sensitivity, simplicity, reproducibility, and high throughput. In this sensor, the Cd²⁺-binding-induced aptamer structure change provoked significant alteration of FA responses. To acquire better sensing performance, we further introduced single phosphorothioate (PS) modification of CBA15 at a specific phosphate backbone position, to enhance aptamer affinity by possible strong interaction between sulfur and Cd²⁺. The aptamer with PS modification at the third guanine (G) nucleotide (CBA15-G3S) had four times higher affinity than CBA15. Using as an aptamer probe CBA15-G3S with a TMR label at the 12th T, we achieved sensitive selective FA detection of Cd²⁺, with a detection limit of 6.1 nM Cd²⁺. This aptamer-based FA sensor works in a direct format for detection without need for labeling Cd²⁺, overcoming the limitations of traditional competitive immuno-FA assay using antibodies and fluorescently labeled Cd²⁺. This FA method enabled the detection of Cd²⁺ in real water samples, showing broad application potential. Full article

(This article belongs to the Special Issue Label-Free Biosensor)

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11 pages, 7929 KiB

Open AccessArticle

A Smartphone-Based Biosensor for Non-Invasive Monitoring of Total Hemoglobin Concentration in Humans with High Accuracy

by Zhipeng Fan, Yong Zhou, Haoyu Zhai, Qi Wang and Honghui He

Biosensors 2022, 12(10), 781; https://doi.org/10.3390/bios12100781 - 21 Sep 2022

Cited by 7 | Viewed by 2894

Abstract

In this paper, we propose a smartphone-based biosensor for detecting human total hemoglobin concentration in vivo with high accuracy. Compared to the existing biosensors used to measure hemoglobin concentration, the smartphone-based sensor utilizes the camera, memory, and computing power of the phone. Thus, the cost is largely reduced. Compared to existing smartphone-based sensors, we developed a highly integrated multi-wavelength LED module and a specially designed phone fixture to reduce spatial errors and motion artifacts, respectively. In addition, we embedded a new algorithm into our smartphone-based sensor to improve the measurement accuracy; an L*a*b* color space transformation and the “a” parameter were used to perform the final quantification. We collected 24 blood samples from normal and anemic populations. The adjusted R² of the prediction results obtained from the multiple linear regression method reached 0.880, and the RMSE reached 9.04, which met the accuracy requirements of non-invasive detection of hemoglobin concentration. Full article

(This article belongs to the Special Issue Label-Free Biosensor)

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Review

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23 pages, 7286 KiB

Open AccessReview

Recent Advances in Field Effect Transistor Biosensors: Designing Strategies and Applications for Sensitive Assay

by Ruisha Hao, Lei Liu, Jiangyan Yuan, Lingli Wu and Shengbin Lei

Biosensors 2023, 13(4), 426; https://doi.org/10.3390/bios13040426 - 27 Mar 2023

Cited by 14 | Viewed by 6138

Abstract

In comparison with traditional clinical diagnosis methods, field–effect transistor (FET)–based biosensors have the advantages of fast response, easy miniaturization and integration for high–throughput screening, which demonstrates their great technical potential in the biomarker detection platform. This mini review mainly summarizes recent advances in FET biosensors. Firstly, the review gives an overview of the design strategies of biosensors for sensitive assay, including the structures of devices, functionalization methods and semiconductor materials used. Having established this background, the review then focuses on the following aspects: immunoassay based on a single biosensor for disease diagnosis; the efficient integration of FET biosensors into a large–area array, where multiplexing provides valuable insights for high–throughput testing options; and the integration of FET biosensors into microfluidics, which contributes to the rapid development of lab–on–chip (LOC) sensing platforms and the integration of biosensors with other types of sensors for multifunctional applications. Finally, we summarize the long–term prospects for the commercialization of FET sensing systems. Full article

(This article belongs to the Special Issue Label-Free Biosensor)

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22 pages, 1092 KiB

Open AccessReview

Label-Free Electrochemical Biosensor Platforms for Cancer Diagnosis: Recent Achievements and Challenges

by Vildan Sanko and Filiz Kuralay

Biosensors 2023, 13(3), 333; https://doi.org/10.3390/bios13030333 - 01 Mar 2023

Cited by 15 | Viewed by 3825

Abstract

With its fatal effects, cancer is still one of the most important diseases of today’s world. The underlying fact behind this scenario is most probably due to its late diagnosis. That is why the necessity for the detection of different cancer types is obvious. Cancer studies including cancer diagnosis and therapy have been one of the most laborious tasks. Since its early detection significantly affects the following therapy steps, cancer diagnosis is very important. Despite researchers’ best efforts, the accurate and rapid diagnosis of cancer is still challenging and difficult to investigate. It is known that electrochemical techniques have been successfully adapted into the cancer diagnosis field. Electrochemical sensor platforms that are brought together with the excellent selectivity of biosensing elements, such as nucleic acids, aptamers or antibodies, have put forth very successful outputs. One of the remarkable achievements of these biomolecule-attached sensors is their lack of need for additional labeling steps, which bring extra burdens such as interference effects or demanding modification protocols. In this review, we aim to outline label-free cancer diagnosis platforms that use electrochemical methods to acquire signals. The classification of the sensing platforms is generally presented according to their recognition element, and the most recent achievements by using these attractive sensing substrates are described in detail. In addition, the current challenges are discussed. Full article

(This article belongs to the Special Issue Label-Free Biosensor)

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96 pages, 7670 KiB

Open AccessReview

Biofunctionalization of Multiplexed Silicon Photonic Biosensors

by Lauren S. Puumala, Samantha M. Grist, Jennifer M. Morales, Justin R. Bickford, Lukas Chrostowski, Sudip Shekhar and Karen C. Cheung

Biosensors 2023, 13(1), 53; https://doi.org/10.3390/bios13010053 - 29 Dec 2022

Cited by 11 | Viewed by 4809

Abstract

Silicon photonic (SiP) sensors offer a promising platform for robust and low-cost decentralized diagnostics due to their high scalability, low limit of detection, and ability to integrate multiple sensors for multiplexed analyte detection. Their CMOS-compatible fabrication enables chip-scale miniaturization, high scalability, and low-cost mass production. Sensitive, specific detection with silicon photonic sensors is afforded through biofunctionalization of the sensor surface; consequently, this functionalization chemistry is inextricably linked to sensor performance. In this review, we first highlight the biofunctionalization needs for SiP biosensors, including sensitivity, specificity, cost, shelf-stability, and replicability and establish a set of performance criteria. We then benchmark biofunctionalization strategies for SiP biosensors against these criteria, organizing the review around three key aspects: bioreceptor selection, immobilization strategies, and patterning techniques. First, we evaluate bioreceptors, including antibodies, aptamers, nucleic acid probes, molecularly imprinted polymers, peptides, glycans, and lectins. We then compare adsorption, bioaffinity, and covalent chemistries for immobilizing bioreceptors on SiP surfaces. Finally, we compare biopatterning techniques for spatially controlling and multiplexing the biofunctionalization of SiP sensors, including microcontact printing, pin- and pipette-based spotting, microfluidic patterning in channels, inkjet printing, and microfluidic probes. Full article

(This article belongs to the Special Issue Label-Free Biosensor)

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20 pages, 3076 KiB

Open AccessReview

Optical Methods for Label-Free Detection of Bacteria

by Pengcheng Wang, Hao Sun, Wei Yang and Yimin Fang

Biosensors 2022, 12(12), 1171; https://doi.org/10.3390/bios12121171 - 15 Dec 2022

Cited by 11 | Viewed by 3612

Abstract

Pathogenic bacteria are the leading causes of food-borne and water-borne infections, and one of the most serious public threats. Traditional bacterial detection techniques, including plate culture, polymerase chain reaction, and enzyme-linked immunosorbent assay are time-consuming, while hindering precise therapy initiation. Thus, rapid detection of bacteria is of vital clinical importance in reducing the misuse of antibiotics. Among the most recently developed methods, the label-free optical approach is one of the most promising methods that is able to address this challenge due to its rapidity, simplicity, and relatively low-cost. This paper reviews optical methods such as surface-enhanced Raman scattering spectroscopy, surface plasmon resonance, and dark-field microscopic imaging techniques for the rapid detection of pathogenic bacteria in a label-free manner. The advantages and disadvantages of these label-free technologies for bacterial detection are summarized in order to promote their application for rapid bacterial detection in source-limited environments and for drug resistance assessments. Full article

(This article belongs to the Special Issue Label-Free Biosensor)

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27 pages, 11529 KiB

Open AccessReview

New Horizons for MXenes in Biosensing Applications

by Decheng Lu, Huijuan Zhao, Xinying Zhang, Yingying Chen and Lingyan Feng

Biosensors 2022, 12(10), 820; https://doi.org/10.3390/bios12100820 - 02 Oct 2022

Cited by 23 | Viewed by 3376

Abstract

Over the last few decades, biosensors have made significant advances in detecting non-invasive biomarkers of disease-related body fluid substances with high sensitivity, high accuracy, low cost and ease in operation. Among various two-dimensional (2D) materials, MXenes have attracted widespread interest due to their unique surface properties, as well as mechanical, optical, electrical and biocompatible properties, and have been applied in various fields, particularly in the preparation of biosensors, which play a critical role. Here, we systematically introduce the application of MXenes in electrochemical, optical and other bioanalytical methods in recent years. Finally, we summarise and discuss problems in the field of biosensing and possible future directions of MXenes. We hope to provide an outlook on MXenes applications in biosensing and to stimulate broader interests and research in MXenes across different disciplines. Full article

(This article belongs to the Special Issue Label-Free Biosensor)

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