Examples of microfluidic chip-based detection technologies and applications

Microfluidics is a technological tool for precision manipulation of tiny-scale fluids, using the unique scale effect inside the microchannel to significantly enhance the reaction efficiency and accuracy in a tiny space, thus realizing the goals of miniaturization, integration, rapidity and automation of the experimental process.

The core carrier of this technology is a microfluidic chip, also known as a “lab-on-a-chip,” which can integrate a series of experimental steps, such as sample collection, pre-processing, and analysis and detection, on a chip that is only a few square centimeters in size.

By utilizing unique effects such as surface tension, microfluidic resistance, and energy dissipation, microfluidic chips can precisely regulate the direction of fluid flow and shorten the reaction time to build a highly miniaturized experimental environment.

Microfluidic chips can be fabricated using a variety of substrate materials, including paper-based materials, organic polymers (e.g., PDMS, PMMA, PC, etc.), quartz glass, and hydrogels.

The chip preparation process involves a variety of precision processing techniques, such as printing, lithography, molding, thermoforming and 3D printing. By choosing different materials and processing methods, the stability and functionality of microfluidic chips can be tuned to suit different applications.

Microfluidic chips show excellent application prospects in biomedical research, environmental monitoring, food safety testing, clinical diagnosis and drug screening.

Currently, traditional antibiotic detection methods include ultraviolet-visible spectrophotometry, liquid chromatography, gas chromatography-mass spectrometry and enzyme-linked immunoassay.

Among them, liquid chromatography and its coupled techniques are more widely used, with the advantages of good stability, low detection limit and high detection sensitivity.

However, these methods still have the problems of complicated detection process, the need for professional detectors and equipment, and cannot meet the requirements of daily immediate, on-site detection, and high cost, the development of rapid, portable, low-cost detection system has become an important breakthrough to realize the immediate detection of antibiotics.

Types of microfluidic chip-based sensors

In the rapid detection of antibiotics, microfluidics establishes a miniaturized, portable and high-throughput detection platform, which provides the possibility of immediate and rapid detection of small amounts or even trace samples containing antibiotic residues.

Sensors with good integration performance with microfluidic chips are the key to this. According to the different detection principles, the sensor detection technology of microfluidic chip can be categorized into optical detection, electrochemical detection and mass spectrometry detection.

Optical detection techniques mainly include fluorescence detection, chemiluminescence detection, colorimetric detection, and surface-enhanced Raman scattering optics detection.

Fluorescence detection is a method of determining the content of a target analyte by detecting the intensity of the fluorescence signal produced by the target or a marker (e.g., organic fluorescent dyes, inorganic fluorescent complexes, fluorescent quantum dots, nano-luminescent materials, etc.).

This technique is widely used because of its high sensitivity, good reproducibility, and ease of operation, and is particularly suitable for trace analysis and real-time monitoring.

Chemiluminescence detection is a technology that determines the content of a target analyte by detecting the intensity of luminescence generated by the chemical energy absorbed by a luminophore in the redox reaction of antibiotics, enzyme-catalyzed reactions, and so on.

This technique has the advantages of high sensitivity and easy miniaturization, but it requires that the luminescent reagent and the substance to be detected can be mixed efficiently and is limited to systems with significant chemiluminescent effects.

Colorimetric assay is a method of quantitative determination based on the color change of a target analyte in reaction with a color developer.

The technique is inexpensive, easy to operate, instantaneous, and can quickly and intuitively display test results, but has low sensitivity, quantification, and reliability, and the results are greatly affected by temperature and time, which makes it unsuitable for analyzing complex samples.

Surface Enhanced Raman Scattering (SERS) detection is a method that enhances the Raman scattering signal by adsorbing a target molecule on a metal surface and is suitable for the highly sensitive detection of trace antibiotic residues.

The technique is fast and has a low detection limit, but sample preparation is complex and costly, and the reproducibility and stability of the base liner is more difficult to control.

Electrochemical detection of antibiotic residues is achieved by recognizing the electrochemical signals generated by the interaction of the molecule and the target, such as changes in current, voltage or electrochemical impedance.

Electrochemical detection is characterized by good selectivity, compatibility, and ease of miniaturization and integration, but requires that the target analyte be electrochemically active, and reproducibility may be poor.

Mass spectrometry is a technology that combines microfluidic chips with mass spectrometry, whereby the sample is pre-treated (enriched or separated) by the microfluidic chip and then fed into the mass spectrometer for precise mass analysis.

This technique is suitable for the detection of trace antibiotics and the simultaneous determination of multiple components, and can provide efficient and accurate qualitative and quantitative analysis of antibiotics. The mass spectrometry detection technique has the advantages of high sensitivity, short detection time, good quantification and identification of the structure of target analytes.

However, the technology also has some limitations, such as the mass spectrometer is large in size and high in cost, which does not meet the requirements of chip miniaturization, and the interface between the chip and the mass spectrometer is more complicated and requires professional operation, which increases the difficulty of practical application.

Application of microfluidic technology in the rapid detection of antibiotics

Antibiotics spread rapidly through animal secretions, sewage and medical waste, and enter and accumulate in animals or humans through the food chain, and excessive antibiotics seriously threaten human health. How to detect residual antibiotics quickly, accurately and at low cost is an urgent problem.

Application of microfluidics to food safety analysis

During livestock rearing, antibiotic drugs are usually used in large quantities by farmers for the prevention and treatment of infectious diseases.

The misuse of antibiotics and their accumulation in the food chain have led to serious excesses of antibiotics in foods such as dairy, meat and aquatic products, posing great risks to food safety and human health.

Therefore, strengthening the detection and monitoring of antibiotic residues in food is a key way to address the problem.

Compared with traditional detection methods, microfluidic analysis technology can realize miniaturized, rapid and instantaneous extraction and detection of antibiotic residues in various types of foods, and has been applied to the rapid detection of antibiotics in foods such as dairy products, meat, eggs and honey.

Application of microfluidic technology in environmental pollution detection

Antibiotics in the environment mainly originate from domestic sewage, wastewater from animal husbandry and aquaculture, industrial wastewater from pharmaceutical companies and medical wastewater, etc., and are diffused, circulated and enriched through the media of water, soil, livestock and aquatic products.

Therefore, the establishment of reliable on-site rapid monitoring methods for antibiotic residues is essential for early warning and surveillance of antibiotic contamination in the environment.

The miniaturization and portability of microfluidics allow it to perform low volume, rapid qualitative and quantitative analyses of analytes in complex, dynamic environmental samples with little operational expertise required, making it easy to promote its use in practice.

Application of microfluidics in pharmaceutical monitoring

Antibiotics are the most commonly prescribed drugs for the clinical treatment of various types of inflammation caused by bacterial infections. Misuse and overuse can lead to resistance and allergic reactions of germs to antibiotics, which is not conducive to the prevention and treatment of diseases.

Therefore, strict monitoring of antibiotic dosage in clinical treatment or care is important. Effective drug therapy depends on individual pharmacokinetics and efficacy, and immediate metabolism monitoring of antibiotic drugs in vivo is important for the diagnosis of relevant diseases, individualized treatment plans and dosage determination.

High-throughput, rapid and micronized detection of antibiotics in blood, urine and other medical biological samples can be achieved using microfluidics.