Development of bismuth sulfide nanorods and polyamidoamine dendrimer on reduced graphene oxide as electrode nanomaterials for electrochemical determination of salbutamol.

Dendrimers, a new class of nanomaterials, are receiving more attention in various fields. In this study, by combining the advantages of polyamidoamine (PAMAM) dendrimer with reduced graphene oxide (rGO) and bismuth sulfide (Bi2S3), we came to design a new composite and its application for electrochemical sensors was investigated for the first time. As a new approach in the preparation of the composite, PAMAM was used for the first time to increase the surface of Bi2S3 with rGO, which ultimately led to an increase in the active surface area of the sensor (5 times compared to the bare electrode). For the first time, we used the sonochemical method for interaction between PAMAM with Bi2S3 and rGO, which was a simpler and faster method to prepare the composite. The purposeful design of the composite was done by using the experimental design method to obtain the optimum composition of components. The new nanocomposite was successfully applied for simple and sensitive electrochemical sensing of salbutamol for controlling the health of food. Salbutamol is used as a prohibited additive in animal and poultry feed. The sensor has good sensitivity (35 times increase compared to the bare electrode) and a low detection limit (1.62 nmol/L). Moreover, it has acceptable selectivity, good repeatability (1.52-3.50%), good reproducibility (1.88%), and satisfactory accuracy (recoveries: 84.6-97.8%). An outstanding feature of the sensor is its broad linear range (5.00-6.00 × 102 nmol/L). This sensor is well suited for the determination of salbutamol in milk, sausage, and livestock and poultry feed samples.

Microfluidics by Additive Manufacturing for Wearable Biosensors: A Review.

Wearable devices are nowadays at the edge-front in both academic research as well as in industry, and several wearable devices have been already introduced in the market. One of the most recent advancements in wearable technologies for biosensing is in the area of the remote monitoring of human health by detection on-the-skin. However, almost all the wearable devices present in the market nowadays are still providing information not related to human 'metabolites and/or disease' biomarkers, excluding the well-known case of the continuous monitoring of glucose in diabetic patients. Moreover, even in this last case, the glycaemic level is acquired under-the-skin and not on-the-skin. On the other hand, it has been proven that human sweat is very rich in molecules and other biomarkers (e.g., ions), which makes sweat a quite interesting human liquid with regards to gathering medical information at the molecular level in a totally non-invasive manner. Of course, a proper collection of sweat as it is emerging on top of the skin is required to correctly convey such liquid to the molecular biosensors on board of the wearable system. Microfluidic systems have efficiently come to the aid of wearable sensors, in this case. These devices were originally built using methods such as photolithographic and chemical etching techniques with rigid materials. Nowadays, fabrication methods of microfluidic systems are moving towards three-dimensional (3D) printing methods. These methods overcome some of the limitations of the previous method, including expensiveness and non-flexibility. The 3D printing methods have a high speed and according to the application, can control the textures and mechanical properties of an object by using multiple materials in a cheaper way. Therefore, the aim of this paper is to review all the most recent advancements in the methods for 3D printing to fabricate wearable fluidics and provide a critical frame for the future developments of a wearable device for the remote monitoring of the human metabolism directly on-the-skin.