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The microneedles have attracted great interests for a wide range of transdermal biomedical applications, such as biosensing and drug delivery, due to the advantages of being painless, semi-invasive, and sustainable. The ongoing challenges are the materials and fabrication methods of the microneedles in order to obtain a specific shape, configuration and function of the microneedles to achieve a target biomedical application. Here, this review would introduce the types of materials of the microneedles firstly. The hardness, Young's modulus, geometric structure, processability, biocompatibility and degradability of the microneedles are explored as well. Then, the fabrication methods for the solid and hollow microneedles in recent years are reviewed in detail, and the advantages and disadvantages of each process are analyzed and compared. Finally, the biomedical applications of the microneedles are reviewed, including biosensing, drug delivery, body fluid extraction, and nerve stimulation. It is expected that this work provides the fundamental knowledge for developing new microneedle devices, as well as the applications in a variety of biomedical fields. [ABSTRACT FROM AUTHOR]

The development of the electrochemical biosensing approaches for creatine kinase (CK) has attracted great interests for clinical and healthcare applications. One of the major challenges is the synergistic integration of the sensing principle, the device configuration, the fabrication method, and the materials on the devices. In recent years, there have been various types of the enzymatic biosensors, the electrochemical immunosensors, and the electrochemiluminescence-based approaches that have been used to construct the electrochemical biosensors for CK. To successfully construct an electrochemical biosensor for CK, there are several interesting questions: What sensing principle should be chosen? Which device configuration should be used? What materials and fabrication methods should be adopted to construct the device? How are the signals generated and detected? What is the current commercial status for the electrochemical biosensors for CK. This review will highlight the early attempts to address these research challenges and explore the fundamental and practical aspects for the CK electrochemical biosensors. [ABSTRACT FROM AUTHOR]

The development of a simple directly wearable approach for the rapid, specific and sensitive determination of biomarkers is of great importance to a variety of biomedical applications. Dental floss can provide a unique device platform for sensing of oral biomarkers. We show here for the first time the development of a smart dental floss for biosensing of glucose. The sensor was made by painting carbon graphite ink and Ag/AgCl ink on dental floss. Via the immobilization of glucose oxidase, we show the detection of glucose with a detection range of 0.048 mM to 19.5 mM and a response time of about 2 min. It is expected that our results could provide new exciting opportunities for the development of various flexible smart sensing devices in oral health applications. [ABSTRACT FROM AUTHOR]

Developing a new biosensing platform for the direct detection of analytes in beverages can offer significant, new opportunities for medical science, microbiology, nutrition studies, and the food industry. Cork stoppers are widely used for beverage bottles, and the stopper’s inner sides can be in direct contact with beverages. Here, we show for the first time the development of an amperometric biosensor on a cork with a two electrode configuration containing carbon nanotube as working electrode and Ag/AgCl as reference electrode. The sensor displays sensitive detection of hydrogen peroxide. Via the immobilization of alcohol oxidase, the sensor can detect ethanol. We anticipate that these results could offer exciting opportunities for the fundamental studies of non-conventional biosensors, as well as provide a wide range of applications in the food and beverage industry. [ABSTRACT FROM AUTHOR]

The development of new signal systems for electrical biosensors could provide exciting new opportunities for biomedical analysis, pollutant monitoring, and explosive detection. The signal systems for commercial portable sensors involve the integration of a battery and a circuit conditioning system to power an amperometric biosensor. However, this increases the size and complexity of the entire system. In this study, we develop a simple amperometric biosensor that is directly powered by a button cell battery for the detection of lactate. A two-electrode sensing transducer was printed on cardboard or integrated on a ring. It was directly powered by a button cell battery, and connected to a multimeter for current measurement. This sensor showed a sensitive detection range of 0.04762–9.21429 mM and short measuring time of 2 min. These results show that this system can achieve an excellent sensing performance, and the construction of this new sensing system directly powered by a button cell battery offers a new method for further developing a wide range of miniaturized, flexible, portable, or wearable sensing systems, and these could be used in detecting various analytes that are important in medical diagnosis and environmental monitoring. [ABSTRACT FROM AUTHOR]

The development of new bioelectronic sensors could enable significant advances in clinical analysis, environmental monitoring, and defense. Cotton fabric is a wearable material, which can contact the skin closely. Here, we demonstrate for the first time the development of a wearable amperometric biosensor on a cotton fabric for the detection of lactate. The sensor is constructed by printing carbon graphite ink and Ag/AgCl ink on a cotton fabric as the working, reference, and counter electrode. Via the immobilization of lactate oxidase, the sensor shows a sensitive detection of lactate with a detection range of 0.05–1.5 mM and a rapid measuring time of around 5 min. We anticipate that these results could open exciting opportunities for fundamental studies and practical applications of wearable bioelectronics in areas ranging from healthcare to defense. [ABSTRACT FROM AUTHOR]

Uric acid and creatinine are essential biomarkers for many diseases, such as gout, hyperuricemia, kidney diseases and heart diseases. Electrochemical biosensors are promising candidates for detecting uric acid and creatinine. However, the sensors always suffer from low stability that would limit their practical applications. In this work, we report a new multilayer enzyme matrix to enhance the room-temperature storage stabilities of uric acid and creatinine biosensors significantly. The enzymes are first dropped on the electrode surface directly, then a layer of glutaraldehyde was deposited on the surface of the enzyme layer, and after that, another layer of a polyvinyl alcohol (PVA)/poly(ethylene glycol) (PEG) composite was further placed on the surface of the glutaraldehyde layer, with drying in between. The stabilities of uric acid and creatinine biosensors were enhanced significantly, and the sensors can maintain highly stable sensing performance for over 4 months with a storage at room temperature. It is anticipated that this work could open new avenues for the practical applications of the uric acid and creatinine biosensors. [Display omitted] • The work reports a new multilayer enzyme matrix to enhance the room-temperature storage stabilities of biosensors. • The method is based on a sequential deposition of enzyme, glutaraldehyde, and polyvinyl alcohol/poly(ethylene glycol). • The sensors can maintain highly stable sensing performance for over 4 months with a storage at room temperature. • The sensors can perform accurate detection of uric acid and creatinine in whole blood samples. [ABSTRACT FROM AUTHOR]

Developing a simple and direct approach for interfacing a sensor and a target analyte is of great interest for fields such as medical diagnosis, threat detection, food quality control, and environmental monitoring. Gloves provide a unique interface for sensing applications. Here, we show for the first time the development of wearable carbon nanotube (CNT)-based amperometric biosensors painted onto gloves as a new sensing platform, used here for the determination of lactate. Three sensor types were studied, configured as: two CNT electrodes; one CNT electrode, and an Ag/AgCl electrode, and two CNT electrodes and an Ag/AgCl electrode. The sensors are constructed by painting the electrodes using CNT or Ag/AgCl inks. By immobilizing lactate oxidase onto the CNT-based working electrodes, the sensors show sensitive detections of lactate. Comparison of sensor performance shows that a combination of CNT and Ag/AgCl is necessary for highly sensitive detection. We anticipate that these findings could open exciting avenues for fundamental studies of wearable bioelectronics, as well as practical applications in fields such as healthcare and defense. [ABSTRACT FROM AUTHOR]

Developing a simple and direct approach for sensitive, specific, and rapid detection of metabolic compounds is of great importance for a variety of biological, medical, and food applications. Tubes are a highly portable and accessible container shape which are widely used for scientific research in cell biology and chemical synthesis, and which are also of great use in domestic health care applications. Here, we show for the first time the development of a tube-based painted amperometric biosensor for the detection of glucose and lactate. The sensor was prepared by printing carbon graphite and silver/silver chloride inks on the interior wall of the tube and then immobilizing glucose oxidase or lactate oxidase on the sensor. The sensor showed a sensitive, rapid, and reliable detection of glucose and lactate. We anticipate that these results could open new avenues for the development of painted biosensors, and toward advanced biosensor applications. [ABSTRACT FROM AUTHOR]