Loading and Release of Charged and Neutral Fluorescent Dyes into and from Mesoporous Materials: A Key Role for Sensing Applications

Abstract

The aim of this study is to determine the efficiency of loading and release of several zwitterionic, neutral, anionic and cationic dyes into/from mesoporous nanoparticles to find the optimum loading and release conditions for their application in detection protocols. The loading is carried out for MCM-41 type silica supports suspended in phosphate-buffered saline (PBS) buffer (pH 7.4) or in acetonitrile, involving the dyes (rhodamine B chloride, rhodamine 101 chloride, rhodamine 101 perchlorate, rhodamine 101 inner salt, meso-(4-hydroxyphenyl)-BODIPY, sulforhodamine B sodium salt and fluorescein 27). As a general trend, rhodamine-based dyes are loaded with higher efficiency, when compared with BODIPY and fluorescein dyes. Between the rhodamine-based dyes, their charge and the solvent in which the loading process is carried out play important roles for the amount of cargo that can be loaded into the materials. The delivery experiments carried out in PBS buffer at pH 7.4 reveal for all the materials that anionic dyes are more efficiently released compared to their neutral or cationic counterparts. The overall best performance is achieved with the negatively charged sulforhodamine B dye in acetonitrile. This material also shows a high delivery degree in PBS.

Supraparticles for Bare‐Eye H2 Indication and Monitoring: Design, Working Principle, and Molecular Mobility

“…Mesoporous particles offer a defined pore structure as well as a high specific surface area and are ideally suited as a potential additive material. [ 47,48 ] The solid porous framework provides a confined space for capillary condensation of water [ 49,50 ] that enables the transport of aqueous molecular solutes, [ 51 ] that is, dyes, [ 52 ] while remaining readily accessible for small gas molecules. [ 53,54 ] As an alternative to conventional synthesis routes, [ 48,55 ] the assembly of NPs into a hierarchical suprastructure was established as a versatile fabrication route for mesoporous particles with designed confined space and particular advantages for catalysis applications, which result from the cooperative interplay of the NP building blocks.…”

Immunochemical Design of Antibody-Gated Indicator Delivery (gAID) Systems Based on Mesoporous Silica Nanoparticles

“…5 was prepared in ACN (subscript "A"). 36 Then, a portion of this solution (44 mL) was added to a suspension of S2 (55 mg), obtaining a dye concentration of 0.8 mmol g −1 solid. The suspension was stirred for 24 h at room temperature.…”

“…29,35 In another work, we assessed the influence of the chemical nature of the indicator dye on the loading and release efficiency into and from mesoporous silica nanoparticles. 36 However, because of the use of a commercially available antibody, 37,38,a these studies could not efficiently elucidate the potential that lies in the tuning of the gatekeeping immunochemistry as such. The latter became possible within the framework of BAM's program to generate antibodies against the most widely used explosives.…”

Toward Label‐Free Optical Multiplexing of Analytes in Indicator Release Lateral Flow Assays via Detection Zones Containing Tailored Capture Materials

“…[9] Because a large number of indicator molecules can be released when a single analyte molecule binds to a biomolecular cap, such systems show intrinsic features of chemical signal amplification, [8,10] allowing for multiplexing, [11] for instance by using more than one gAID material loaded with differently coloured/fluorescent dyes on a single strip, as well as for very sensitive analysis, [12] thus addressing two important challenges in contemporary LFA research. [13] Until today, gAID-type LFAs have been optimized with respect to the porous host material, [14] the loading and release behaviour of indicators [15] and the affinity tuning of the gatekeeping biochemistry. [16] No particular attention has been paid yet to improving assay performance by concentrating the released indicator molecules in a designated focusing zone.…”

“…Until today, gAID‐type LFAs have been optimized with respect to the porous host material, [14] the loading and release behaviour of indicators [15] and the affinity tuning of the gatekeeping biochemistry [16] . No particular attention has been paid yet to improving assay performance by concentrating the released indicator molecules in a designated focusing zone.…”