Molecular gated nanoporous anodic alumina for the detection of cocaine

Abstract

We present herein the use of nanoporous anodic alumina (NAA) as a suitable support to implement “molecular gates” for sensing applications. In our design, a NAA support is loaded with a fluorescent reporter (rhodamine B) and functionalized with a short single-stranded DNA. Then pores are blocked by the subsequent hybridisation of a specific cocaine aptamer. The response of the gated material was studied in aqueous solution. In a typical experiment, the support was immersed in hybridisation buffer solution in the absence or presence of cocaine. At certain times, the release of rhodamine B from pore voids was measured by fluorescence spectroscopy. The capped NAA support showed poor cargo delivery, but presence of cocaine in the solution selectively induced rhodamine B release. By this simple procedure a limit of detection as low as 5 × 10−7 M was calculated for cocaine. The gated NAA was successfully applied to detect cocaine in saliva samples and the possible re-use of the nanostructures was assessed. Based on these results, we believe that NAA could be a suitable support to prepare optical gated probes with a synergic combination of the favourable features of selected gated sensing systems and NAA.

Chromogenic and Fluorogenic Probes for the Detection of Illicit Drugs

“…Martínez‐Máñez and co‐workers implement “molecular gates” onto nanoporous anodic alumina (NAA) to prepare a sensing material for cocaine detection (Figure ) . The NAA support, obtained according to reported procedures, is loaded with rhodamine B and functionalized with (3‐isocyanatopropyl)triethoxysilane.…”

Overview of the Evolution of Silica-Based Chromo-Fluorogenic Nanosensors

“…Other sensory materials using aptamers as caps for the detection of As (III) cation [44], ochratoxin A [45], and cocaine [46], were recently described.…”

Simple Endotoxin Detection Using Polymyxin‐B‐Gated Nanoparticles

“…However, in the presence of the analyte, the pores open due to the interaction of the analyte with the capping ensemble leading to cargo release. [21][22][23][24][25][26] One of the advantages of these solids is the potential existence of amplification features as few analyte molecules may trigger gate opening, and induce the release of a high amount of entrapped dye molecules. Given our interest in exploring the potential use of gated nanomaterials in sensing protocols, we report herein a new nanodevice based on mesoporous silica nanoparticles (MSNs) functionalized with carboxylate moieties and capped with the cationic peptide polymyxin B for the selective and sensitive detection of endotoxin.…”