Monitoring Proteolytic Activity in Real Time: A New World of Opportunities for Biosensors.

Proteases play a pivotal role in several biological processes, from digestion, cell proliferation, and differentiation to fertility. Deregulation of protease metabolism can result in several pathological conditions (i.e., cancer, neurodegenerative disorders, and others). Therefore, monitoring proteolytic activity in real time could have a fundamental role in the early diagnosis of these diseases. Herein, the main approaches used to develop biosensors for monitoring proteolytic activity are reviewed. A comparison of the advantages and disadvantages of each approach is provided along with a discussion of their importance and promising opportunities for the early diagnosis of severe diseases. This new era of biosensors can be characterized by the ability to control and monitor biological processes, ultimately improving the potential of personalized medicine.

Density Gradient Selection of Colloidal Silver Nanotriangles for Assembling Dye-Particle Plasmophores.

A simple method based on sucrose density gradient centrifugation is proposed here for the fractionation of colloidal silver nanotriangles. This method afforded particle fractions with surface plasmon resonances, spanning from red to infrared spectral ranges that could be used to tune optical properties for plasmonic applications. This feature was exemplified by selecting silver nanotriangle samples with spectral overlap with Atto-655 dye's absorption and emission in order to assemble dye-particle plasmophores. The emission brightness of an individual plasmophore, as characterized by fluorescence correlation spectroscopy, is at least 1000-fold more intense than that of a single Atto-655 dye label, which renders them as promising platforms for the development of fluorescence-based nanosensors.