{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T15:31:20Z","timestamp":1787671880431,"version":"build-2736575974"},"reference-count":34,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2013,8,6]],"date-time":"2013-08-06T00:00:00Z","timestamp":1375747200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Toxins"],"abstract":"<jats:p>Botulinum neurotoxins are one of the most potent toxins known to man. Current methods of detection involve the quantification of the toxin but do not take into account the percentage of the toxin that is active. At present the assay used for monitoring the activity of the toxin is the mouse bioassay, which is lengthy and has ethical issues due to the use of live animals. This report demonstrates a novel assay that utilises the endopeptidase activity of the toxin to detect Botulinum neurotoxin in a pharmaceutical sample. The cleaving of SNAP-25 is monitored via UV-Visible spectroscopy with a limit of detection of 373 fg\/mL and has been further developed into a high throughput method using a microplate reader detecting down to 600 fg\/mL of active toxin. The results show clear differences between the toxin product and the placebo, which contains the pharmaceutical excipients human serum albumin and lactose, showing that the assay detects the active form of the toxin.<\/jats:p>","DOI":"10.3390\/toxins5081381","type":"journal-article","created":{"date-parts":[[2013,8,6]],"date-time":"2013-08-06T12:33:17Z","timestamp":1375792397000},"page":"1381-1391","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["A Label Free Colorimetric Assay for the Detection of  Active Botulinum Neurotoxin Type A by SNAP-25  Conjugated Colloidal Gold"],"prefix":"10.3390","volume":"5","author":[{"given":"Jennifer","family":"Halliwell","sequence":"first","affiliation":[{"name":"School of Chemistry, Bangor University, Bangor, Gwynedd, Wales LL57 2DG, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Christopher","family":"Gwenin","sequence":"additional","affiliation":[{"name":"School of Chemistry, Bangor University, Bangor, Gwynedd, Wales LL57 2DG, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2013,8,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"304","DOI":"10.1016\/j.vascn.2010.01.003","article-title":"Comparison of the primary rat spinal cord cell (RSC) assay and the mouse bioassay for botulinum neurotoxin type A potency determination","volume":"61","author":"Pellett","year":"2010","journal-title":"J. Pharmacol. Toxicol. Method."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"4309","DOI":"10.1128\/AEM.00617-08","article-title":"Development of an in vitro activity assay as an alternative to the mouse bioassay for Clostridium botulinum neurotoxin type A","volume":"74","author":"Rasooly","year":"2008","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"392","DOI":"10.1016\/j.toxicon.2008.12.016","article-title":"Tandem fluorescent proteins as enhanced FRET-based substrates for botulinum neurotoxin activity","volume":"53","author":"Ho","year":"2009","journal-title":"Toxicon"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1705","DOI":"10.1002\/elps.200405888","article-title":"Microfluidic tectonics platform: A colorimetric, disposable botulinum toxin enzyme-linked immunosorbent assay system","volume":"25","author":"Moorthy","year":"2004","journal-title":"Electrophoresis"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1016\/j.jim.2012.03.008","article-title":"Rapid and selective detection of botulinum neurotoxin serotype-A and -B with a single immunochromatographic test strip","volume":"380","author":"Ching","year":"2012","journal-title":"J. Immunol. Method."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"240","DOI":"10.1016\/j.anaerobe.2011.12.001","article-title":"Botulinum toxin: Therapeutic agent to cosmetic enhancement to lethal biothreat","volume":"18","author":"Katona","year":"2012","journal-title":"Anaerobe"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"14316","DOI":"10.1021\/bi701564f","article-title":"Comparative role of neurotoxin-associated proteins in the structural stability and endopeptidase activity of botulinum neurotoxin complex types A and E","volume":"46","author":"Kukreja","year":"2007","journal-title":"Biochemistry"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"591","DOI":"10.1146\/annurev.biochem.051908.125345","article-title":"Botulinum neurotoxin: A marvel of protein design","volume":"79","author":"Montal","year":"2010","journal-title":"Annu. Rev. Biochem."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"913","DOI":"10.3390\/toxins4100913","article-title":"Clinical uses of botulinum neurotoxins: Current indications, limitations and future developments","volume":"4","author":"Chen","year":"2012","journal-title":"Toxins"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"13806","DOI":"10.1021\/ja905134d","article-title":"Gold nanoparticle based label-free SERS probe for ultrasensitive and selective detection of trinitrotoluene","volume":"131","author":"Dasary","year":"2009","journal-title":"J. Am. Chem. Soc."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"10912","DOI":"10.1073\/pnas.0900975106","article-title":"Detection and differentiation of normal, cancerous, and metastatic cells using nanoparticle-polymer sensor arrays","volume":"106","author":"Bajaj","year":"2009","journal-title":"Proc. Nat. Acad. Sci. USA"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"669","DOI":"10.1021\/ac8020592","article-title":"Aptamer-functionalized gold nanoparticles as probes in a dry-reagent strip biosensor for protein analysis","volume":"81","author":"Xu","year":"2009","journal-title":"Anal. Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2363","DOI":"10.1002\/cbic.200800282","article-title":"Design of gold nanoparticle-based colorimetric biosensing assays","volume":"9","author":"Zhao","year":"2008","journal-title":"Chembiochem"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2051","DOI":"10.1007\/s00216-009-2640-0","article-title":"Label-free aptamer-based colorimetric detection of mercury ions in aqueous media using unmodified gold nanoparticles as colorimetric probe","volume":"393","author":"Li","year":"2009","journal-title":"Anal. Bioanal. Chem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"20901","DOI":"10.1021\/jp0638843","article-title":"Optical limiting of gold nanoparticle aggregates induced by electrolytes","volume":"110","author":"Wang","year":"2006","journal-title":"J. Phys. Chem. B"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"833","DOI":"10.1021\/sc400042h","article-title":"Adsorption of a protein monolayer via hydrophobic interactions prevents nanoparticle aggregation under harsh environmental conditions","volume":"1","author":"Blankenburg","year":"2013","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"15067","DOI":"10.1074\/jbc.M111.224493","article-title":"Association of botulinum neurotoxin serotype a light chain with plasma membrane-bound SNAP-25","volume":"286","author":"Chen","year":"2011","journal-title":"J. Biol. Chem."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1351","DOI":"10.1242\/jcs.079095","article-title":"Differential palmitoylation regulates intracellular patterning of SNAP25","volume":"124","author":"Greaves","year":"2011","journal-title":"J. Cell Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"925","DOI":"10.1038\/nature03123","article-title":"Substrate recognition strategy for botulinum neurotoxin serotype A","volume":"432","author":"Breidenbach","year":"2004","journal-title":"Nature"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2869","DOI":"10.1016\/j.bios.2006.12.012","article-title":"The orientationally controlled assembly of genetically modified enzymes in an amperometric biosensor","volume":"22","author":"Gwenin","year":"2007","journal-title":"Biosens. Bioelectron."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"10906","DOI":"10.1074\/jbc.M513032200","article-title":"Unique substrate recognition by botulinum neurotoxins serotypes A and E","volume":"281","author":"Chen","year":"2006","journal-title":"J. Biol. Chem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"4839","DOI":"10.1021\/jp810869h","article-title":"Gold nanoparticles decorated with oligo(ethylene glycol) thiols: Enhanced hofmeister effects in colloid-protein mixtures","volume":"113","author":"Zhang","year":"2009","journal-title":"J. Phys. Chem. C"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"6903","DOI":"10.1021\/bi990086c","article-title":"Enhancement of the endopeptidase activity of botulinum neurotoxin by its associated proteins and dithiothreitol","volume":"38","author":"Cai","year":"1999","journal-title":"Biochemistry"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"9621","DOI":"10.1074\/jbc.M611211200","article-title":"Mechanism of substrate recognition by botulinum neurotoxin serotype A","volume":"282","author":"Chen","year":"2007","journal-title":"J. Biol. Chem."},{"key":"ref_25","first-page":"S49","article-title":"Limit of blank, limit of detection and limit of quantitation","volume":"29","author":"Armbruster","year":"2008","journal-title":"Clin. Biochem. Rev."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2198","DOI":"10.3390\/toxins2082198","article-title":"Characterization of SNARE cleavage products generated by formulated botulinum neurotoxin type-a drug products","volume":"2","author":"Hunt","year":"2010","journal-title":"Toxins"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1007\/s11940-003-0020-1","article-title":"Botulism","volume":"5","author":"Davis","year":"2003","journal-title":"Curr. Treat Opt. Neurol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"28","DOI":"10.1016\/j.ab.2012.02.038","article-title":"A functional dual-coated (FDC) microtiter plate method to replace the botulinum toxin LD50 test","volume":"425","author":"Liu","year":"2012","journal-title":"Anal. Biochem."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"7687","DOI":"10.1128\/AEM.01664-12","article-title":"Detection of botulinum neurotoxin serotype A, B, and F proteolytic activity in complex matrices with picomolar to femtomolar sensitivity","volume":"78","author":"Dunning","year":"2012","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"769","DOI":"10.4155\/bio.10.31","article-title":"Immunoaffinity chromatography: An introduction to applications and recent developments","volume":"2","author":"Moser","year":"2010","journal-title":"Bioanalysis"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"978","DOI":"10.3390\/toxins2050978","article-title":"The zinc-dependent protease activity of the botulinum neurotoxins","volume":"2","author":"Lebeda","year":"2010","journal-title":"Toxins"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1097","DOI":"10.1039\/a806860g","article-title":"Self-assembling monolayers of helical oligopeptides on gold with applications in molecular electronics","volume":"9","author":"Strong","year":"1999","journal-title":"J. Mater. Chem."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1016\/j.jpba.2010.08.013","article-title":"Release of proteolytic activity following reduction in therapeutic human serum albumin containing products: Detection with a new neoepitope endopeptidase immunoassay","volume":"54","author":"Jones","year":"2011","journal-title":"J. Pharmaceut.Biomed. Anal."},{"key":"ref_34","unstructured":"Gwenin, C.D., and Halliwell, J. (2013). Detection of Botulinum Toxin. (application No. 1310090.4), UK patent."}],"container-title":["Toxins"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-6651\/5\/8\/1381\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T21:48:28Z","timestamp":1760219308000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-6651\/5\/8\/1381"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2013,8,6]]},"references-count":34,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2013,8]]}},"alternative-id":["toxins5081381"],"URL":"https:\/\/doi.org\/10.3390\/toxins5081381","relation":{},"ISSN":["2072-6651"],"issn-type":[{"value":"2072-6651","type":"electronic"}],"subject":[],"published":{"date-parts":[[2013,8,6]]}}}