Smartphone based aptasensors as intelligent biodevice for food contamination detection in food and soil samples: Recent advances

Nowadays, the integration of conventional analytical approaches with smartphones has been developed novel, emerging and affordable devices for improving on-site detection platforms in the fields of food safety. Smartphone-based aptasensors as the next generation of portable aptasensing technique has attracted considerable attention as it offers a semi-automated user interface that can be exploited by inexpert characters. Wireless data transferability is an undeniable advantage that home-testing platforms have as well as it can suggest high computational power. In addition, these types of biodevices can provide real-time monitoring in terms of exchanging digital networks in real-time. To elaborate, the ability of smartphones to connect through the Internet is one of the most critical advantages of smartphone-based aptasensor that can be uploaded to Cloud databases and results can be disseminated as spatio-temporal maps across the globe. This review focused on the recent progress and technical breakthroughs of aptasensor on the smartphone as a groundbreaking enterprise in the field of biochemical analysis, importantly in the aspect of the combination of different types of biosensors including electrochemical, optical and colorimetric. In our opinion, this review can broaden our understanding of using smartphones as a portable sensing approach by addressing the current challenges and future perspectives.

Lateral patterns of the neural cell adhesion molecule on the surface of hippocampal cells developing in vitro

In monolayer cultures of hippocampal neurons from newborn rats, an immunocytochemical quantitative study was carried out to investigate age-dependent arrangement of the neural cell adhesion molecules in different parts of cell membranes. On the fifth and 12th day in vitro, neural cell adhesion molecules were labelled with specific antibodies and protein A conjugated to colloidal gold particles. Samples of randomly selected electron micrographs that displayed labelled membrane fragments of cell bodies, growth cones, and axons were numerically analysed for the five- and 12-day in vitro neurons. Neural cell adhesion molecules surface topography was quantitatively described and compared, using a statistical stereological approach. The mean surface density of labelled neural cell adhesion molecules was found to be approximately 2.5 times higher in growth cone membranes relative to somatic and axonal membranes in five-day in vitro neurons. By the 12th day in vitro, this density decreases in somatic membranes (approximately 18%) and increases in axonal membranes (approximately 60%). Representative spectra of lateral intervals between labels as well as images that show typical topography of label on membrane surfaces were simulated. The results revealed regular patterns of neural cell adhesion molecules on the somatic surface and allowed consideration of neural cell adhesion molecules arrangement in a view of membrane adhesion properties. Participation of cytoskeleton in neural cell adhesion molecules rearrangement is discussed.

Changes in the neural cell adhesion molecule patterns on the rat glial cell surfaces with development and contact formation in vitro

In monolayer cultures of newborn rat hippocampal cells, immunogold-labelling at the electron microscope level was used to study quantitatively the neural cell adhesion molecule (N-CAM) arrangement on the surface of glial soma and processes on 5 and 12 days in vitro (DIV). Four corresponding samples of micrographs were formed. To quantify the labelling, a stochastic geometry approach was used. Spectra of lateral distances between labels as well as simulated images of the surface label arrangement (invisible in micrographs) were derived and compared. The data show that, on both 5 and 12 DIV, N-CAM density on the surface of processes is approximately 2 times higher than that in somata; 12-DIV cells showing a lower (approximately 25%) N-CAM surface density as compared with the 5-DIV cells. This suggests that N-CAM expression in glia surfaces decreases while the cells form contacts, and N-CAM sorting between soma and processes remains stable. The simulated topographies of the lateral N-CAM arrangement might highlight fundamental mechanisms that underlie formation of the neural network.