Analysis of Mycotoxins in Beer Using a Portable Nanostructured Imaging Surface Plasmon Resonance Biosensor

Abstract

A competitive inhibition immunoassay is described for the mycotoxins deoxynivalenol (DON) and ochratoxin A (OTA) in beer using a portable nanostructured imaging surface plasmon resonance (iSPR) biosensor, also referred to as imaging nanoplasmonics. The toxins were directly and covalently immobilized on a 3-dimensional carboxymethylated dextran (CMD) layer on a nanostructured iSPR chip. The assay is based on competition between the immobilized mycotoxins and free mycotoxins in the solution for binding to specific antibodies. The chip surface was regenerated after each cycle, and the combination of CMD and direct immobilization of toxins allowed the chips to be used for more than 450 cycles. The limits of detection (LODs) in beer were 17 ng/mL for DON and 7 ng/mL for OTA (or 0.09 ng/mL after 75 times enrichment). These LODs allowed detection of even less than 10% depletion of the tolerable daily intake of DON and OTA by beer. Significant cross-reactivity of anti-DON was observed toward DON-3-glucoside and 3-acetyl-DON, while no cross-reactivity was seen for 15-acetyl-DON. A preliminary in-house validation with 20 different batches of beer showed that both toxins can be detected at the considered theoretical safe level for beer. The assay can be used for in-field or at-line detection of DON in beer and also in barley without preconcentration, while OTA in beer requires an additional enrichment step, thus making the latter in its present form less suitable for field applications.

Two New Fluorogenic Aptasensors Based on Capped Mesoporous Silica Nanoparticles to Detect Ochratoxin A

“…This weaker attachment of the aptamer to the surface favors the aptamer–OTA interaction, the displacement of the aptamer, and cargo delivery. However, both LOD values comply with those established by the legislation and are similar to or better than most published techniques for the detection of OTA (see Table S4) …”

“…This weaker attachment of the aptamer to the surfacef avors the aptamer-OTAi nteraction, the displacement of the aptamer,a nd cargo delivery.H owever,b oth LOD values comply with those established by the legislation and are similar to or better than most published techniques for the detection of OTA( see Ta ble S4). [42][43][44][45][46][47][48][49][50][51][52][53][54] Additionally,t he selectivity of S3 (Figure 3i nb lack) and S5 ( Figure 3i ng rey) to OTAw as also studied. With this aim, cargo releasefrom S3 and S5 was testedi np resence of OTA, fumonisin B1 and aflatoxin B1.…”

Biochip Spray: Simplified Coupling of Surface Plasmon Resonance Biosensing and Mass Spectrometry

“…29 Large molecular weight analytes, such as proteins, yield high signals in SPR sensing with an antibody biochip and may be analyzed in a direct SPR assay (Figures S2A and S4A) without signal enhancer. Subsequently, the binding molecules may be identified in a direct manner by MS using MALDI 7,8 or following elution 3 using ESI MS or potentially by Biochip Spray MS (Figure S4A).…”

“…Please note that, as for any large-scale routine SPR analysis of small molecules, a competitive indirect mode using an immobilized DON biochip (Figures S2D and S4C) would be the method of choice since such a chip will show extreme durability and, in the present case, could be used more than 400 times. 29 Obviously, an immobilized DON chip would not directly trap the low molecular weight ligands for subsequent chemical identification by MS. As a way out, a so-called “recovery-chip” approach was applied as demonstrated previously for the coupling of inhibition SPR with nanoLC MS. 4 Such a recovery chip is identical to the SPR screening chip, but the ligand binding interaction is reversed, i.e., immobilized antibodies on the chip to trap sufficient numbers of analyte molecules for chemical identification (Figure S4D). Thus, the contaminated beer sample was reinjected into the SPR apparatus but now onto a chip containing the anti-DON followed by washing with HBS-EP and water (Figure S4D).…”

High Throughput Detection Methods for Multiplex Mycotoxins

“…Although the colloidal gold nanoparticles and TMB have shown good sensitivity and low limits of detection for color development, different signal enhancement strategies have been developed to significantly improve LOD, sensitivity and stability of the system, which is strongly related with the development of nanomaterial techniques. Graphene, quantum dots, nano-silver and magnetic nanoparticles have been introduced in the system and showed the stable, enhanced signal and wide detection linear ranges [96]. In addition, except nitrocellulose membrane as the support substrate, the three-dimensional porous smart nanomaterial may bring the field to a new level.…”