Ionophore-Based Ion-Selective Nanosensors from Brush Block Copolymer Nanodots

Abstract

The selectivity of ionophore-based sensors is crucial to real applications such as clinical diagnostics and bioimaging. Previous ion-selective nanosensors developed from amphiphilic block copolymers are attractive because of simple fabrication, high stability, and versatility. However, the selectivity was reduced compared with polymeric ion-selective membranes. Here, we present ionophore-based nanosensors from graft copolymer nanodots (23.5 ± 3.8 nm in diameter) with significantly improved selectivity and excellent stability against high ionic strength and dilution. The improved selectivity was ascribed to the high ion-carrier stability constants inside the nanodots, with log β values of 7.6 and 8.2 for Na+ and K+, respectively. Besides response in the light absorption mode, an intriguing energy transfer in the nanodots resulted in a ratiometric and dual-emission sensing mode. Nanosensors delivered to HeLa cells through endocytosis were found to accumulate in endosomes and lysosomes. As a preliminary application, the sodium ion concentration in diluted human blood serum was successfully determined.

Ionophore-Based Ion-Selective Nanospheres Based on Monomer–Dimer Conversion in the Near-Infrared Region

“…Figure 1b shows a transmission electron microscopy (TEM) image that shows an average diameter around 50 nm, which agrees well with the previously reported nanospheres formed with similar materials. 43 According to the literature, cyanine dyes tend to form Jaggregation or H-aggregation, 44,45 and, in particular, strong Haggregation could occur in aqueous solutions. 46 DTTC has been demonstrated to form dimer in aqueous solutions, 47 which is accompanied by blue-shifted absorption.…”

LipiSensors: Exploiting Lipid Nanoemulsions to Fabricate Ionophore-Based Nanosensors

“…While large LipiSensors can be used for extracellular and in vivo applications, the small sensors can be used for small intracellular compartments to detect the compartmentalization of Ca +2 , transmembrane Ca +2 dynamics, and potentially aiding in characterization of Ca +2 flux from organelles to the cytoplasmic space (and vice versa) [ 43 , 46 , 47 ]. The small LipiSensors in this work are ~120 nm in diameter, but it may be possible to formulate much smaller sizes, as other groups have shown Lipidots with 25 nm [ 28 ] and IBNS with 20 nm diameters [ 27 ].…”

“…Importantly, this structural support function should also work with other materials while maintaining the sensing mechanism as long as the material properties are similar. The fundamental mechanism of IBNS has been demonstrated in a wide range of supporting matrices and is not impacted [ 22 , 23 , 24 , 25 ], as others have demonstrated that it is possible to make sensors with only plasticizer [ 24 ], brush block copolymers [ 27 ], surfactant alone [ 23 ], and even SiO 2 nanoparticles [ 25 ].…”

“…One of the limitations of current polymer-based nanosensors is the challenge of finely tuning their size with formulation-based approaches [ 26 ]. Others have demonstrated the ability to change nanosensor size through changing out the key components (e.g., the polymer or plasticizer) in each formulation, resulting in functional sensors over several size ranges [ 23 , 27 ]. In this work, we demonstrate the ability to tune sensor size using the same components but altering the formulation ratio of these components.…”

Multisensor Systems and Arrays for Medical Applications Employing Naturally-Occurring Compounds and Materials

“…The system was used for the perception of heptanal as a lung cancer biomarker in human blood [ 94 ]. Along with the analysis of cancer biomarkers, electrochemical MSAs can be applied for blood screening for the biomarkers of hypertension [ 95 ], cardiovascular disease [ 96 , 97 ], for evaluation of the concentration of purine nucleotides [ 98 ], metal ions [ 99 ], urea, creatinine and uric acid [ 100 ], etc.…”