722 K. Campbell et al. selectively separating molecules for clean-up and pre- concentration of analytes from complex samples, but they have also been demonstrated in detection assays (Ramstrom et al. 2001; Chianella et al. 2003). The applicability of MIPs as a surface template in the SPR analysis of domoic acid has also been demonstrated (Lotierzo et al. 2004). Mahony et al. (2005) stated that combinatorial chemistry and computational molecular modelling are the most promising concepts for the development of MIPs for enhanced recognition prop- erties. Using this technology with advances in poly- meric materials, in the future there is the potential to develop and design binders with the highest selectivity to the PSP toxin family as a whole. However, the elimination of problems associated with template leaching for quantitative analysis would have to occur. Aptamers Aptamers, first described by Tuerk and Gold (1990), are creating a new wave of enthusiasm as alternative binders to antibodies due to progress in aptamer screening methods (Wang and Jia 2009) and their potential in the field of aptasensors (Wilner and Zayats 2007). Aptamers can be divided into those created from polymers of nucleic acids (RNA and DNA) or amino acids (peptides). Nucleic acid aptamers are small synthetic oligonucleotides of up to 100 base pairs that can bind specifically to a variety of targets, such as whole cells, proteins, drugs, toxins and low molecular weight compounds, with affinities in the nanomolar and sub-nanomolar ranges. They can bind with a high affinity and specificity to a target molecule through complementary shape interactions as a result of their three-dimensional shape. Nucleic acid aptamers are produced by an in vitro process called systematic evolution of ligands by exponential enrichment (SELEX) (Stoltenburg et al. 2007). These aptamers can provide high molecular discrimination in being able to distinguish differences in a methyl group between two compounds (Jenison et al. 1994). Aptamers offer several distinct advantages compared with antibodies or receptors. They are isolated in vitro, and the targets are of a broad spectrum. Following aptamer selection, DNA aptamers with a long shelf life can be prepared with high batch consistency and low cost by automated DNA synthesis, and RNA aptamers can be prepared by simple in vitro transcription. Aptamers are also simple to modify and introduce various reactive groups, affinity tags or reporting moieties essential for biosensor applications. Nucleic acid aptamers have a limited number of structures compared with peptide aptamers, but offer better structural stability. Protein scaffolds are an adaptation of peptide aptamers that may overcome stability issues. Peptide aptamers still require biological systems for selection purposes. Aptamers have been demonstrated in therapeutic applications, in the field of separation chemistry, in environmental and food analysis of chemical contaminants and toxins, and in a number of aptasensor applications (Tombelli et al. 2007; Wilner and Zayats 2007; Stead et al. 2010). These binders are now developing rapidly and may be the one binder group that in future replaces antibodies for diagnostic and detection applications. To date, they offer the best opportunity of finding a single binder for the detection of the whole PSP toxin family or individual binders for each of the varying toxic groups within this family. Conclusion Optical SPR biosensor analysis for PSP toxin detection has been demonstrated over the past five years to be a highly effective rapid screening method that has the potential to reduce the vast number of mouse bioassays performed worldwide. This review has highlighted the key problems associated with antibody cross-reactivity in over- and underestimating total toxicity and how, by using a dual antibody binder system with a generic surface, there is the potential to adjust the cross- reactivity profile to help overcome this problem. Alternative non-antibody-based binders, however, may offer a complete non-animal-based methodology for the detection of PSP toxins by SPR. In addition, advances in SPR technology, with the development of multiplexing multichannel instruments, could help resolve some of the difficulties in binder specificity not relating to toxicity. Multiplex multichannel SPR bio- sensors with highly designed binders such as nucleic acid aptamers (Mok and Li 2008) may be the way forward not only for monitoring phycotoxins, but also for a wide variety of food additives and contaminants. Acknowledgements This study was funded by the European Commission as part of the 6th Framework Programme Integrated Project BioCop (Contract Number FOOD-CT-2004-06988) and the 7th Framewok Project CONffIDENCE (Contract Number 211326). References Abery J. 2001. Detecting the molecular ties that bind. Modern Drug Disc. 4:34–36. Association of Analytical Communities (AOAC). 2005a. AOAC Official Method 959.08. Paralytic shellfish poison. Biological method. In: Official methods of analysis of AOAC International, 18th ed. Gaithersburg (MD): AOAC International; Section 49.10.01. Association of Analytical Communities (AOAC). 2005b. AOAC Official Method 2005.06. Paralytic shellfish