{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T13:38:00Z","timestamp":1792762680442,"version":"4.5.0"},"reference-count":38,"publisher":"American Chemical Society (ACS)","issue":"26","license":[{"start":{"date-parts":[[2019,12,12]],"date-time":"2019-12-12T00:00:00Z","timestamp":1576108800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/pubs.acs.org\/page\/policy\/authorchoice_termsofuse.html"}],"funder":[{"DOI":"10.13039\/501100000855","name":"University of Birmingham","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100000855","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2019,12,24]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Anthocyanins are bioactive compounds naturally found in a variety of leaves, fruits, and vegetables. Anthocyanin pigments undergo a modification in their chemical structure when exposed to different concentrations of hydrogen ions, and they were extensively studied to be used as active elements in biocompatible pH sensors. The ocular pH is a significant parameter to assess the ocular physiology in cases of postocular surgery, keratoconjunctivitis, and ocular rosacea. Contact lenses have the potential to be used as medical diagnostic devices for in situ continuous monitoring of the ocular physiology. Here, anthocyanin-functionalized contact lenses were developed as wearable sensors to monitor the ocular pH. Anthocyanin pigments were extracted from Brassica oleracea and used to functionalize the polymeric matrices of commercial soft contact lenses by soaking and drop-casting processes. Contact lenses responded to the physiological ocular pH of 6.5, 7.0, and 7.5, exhibiting a systematic color shift from pink (pH 6.5) to purple (pH 7.0) and blue (pH 7.5). The functionalization of contact lens sensors was evaluated as a function of the dye concentration. Quantitative values were obtained by comparing the RGB triplets of the colors obtained with the naturally extracted dye and with delphinidin chloride dye in 0.0 to 1.5 mmol L\u20131 aqueous solution. The functionalization of contact lenses was studied as a function of the soaking time, resulting in best results when soaking for 24 h. The dye leakage from the contact lenses in deionized water was evaluated, and a negligible leakage after 18 h was observed. Poly-2-hydroxy ethylmethacrylate contact lenses were fabricated and cross-linked with anthocyanin dye, resulting in a slight color shift upon pH changes from 6.5 to 7.4. Contact lens pH sensors may be used to continuously monitor the ocular pH at point-of-care settings.<\/jats:p>","DOI":"10.1021\/acsomega.9b02638","type":"journal-article","created":{"date-parts":[[2019,12,12]],"date-time":"2019-12-12T09:11:26Z","timestamp":1576141886000},"page":"21792-21798","source":"Crossref","is-referenced-by-count":84,"title":["Anthocyanin-Functionalized\nContact Lens Sensors for\nOcular pH Monitoring"],"prefix":"10.1021","volume":"4","author":[{"given":"Rafia Sarah","family":"Riaz","sequence":"first","affiliation":[{"name":"University of Birmingham , , Edgbaston, ,","place":["Birmingham, U.K., B15 2TT"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohamed","family":"Elsherif","sequence":"additional","affiliation":[{"name":"University of Birmingham , , Edgbaston, ,","place":["Birmingham, U.K., B15 2TT"]},{"name":"Egyptian Atomic Energy Authority , , ,","place":["Cairo, Egypt, 11865"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0332-1606","authenticated-orcid":true,"given":"Rosalia","family":"Moreddu","sequence":"additional","affiliation":[{"name":"University of Birmingham , , Edgbaston, ,","place":["Birmingham, U.K., B15 2TT"]},{"name":"Imperial College London , , South Kensington Campus , ,","place":["London, U.K., SW7 2AZ"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ijaz","family":"Rashid","sequence":"additional","affiliation":[{"name":"University of Birmingham , , Edgbaston, ,","place":["Birmingham, U.K., B15 2TT"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0057-4069","authenticated-orcid":true,"given":"Muhammad Umair","family":"Hassan","sequence":"additional","affiliation":[{"name":"University of Birmingham , , Edgbaston, ,","place":["Birmingham, U.K., B15 2TT"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ali K.","family":"Yetisen","sequence":"additional","affiliation":[{"name":"Imperial College London , , South Kensington Campus , ,","place":["London, U.K., SW7 2AZ"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Haider","family":"Butt","sequence":"additional","affiliation":[{"name":"Khalifa University , , ,","place":["Abu Dhabi, UAE, 127788"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2019,12,12]]},"reference":[{"key":"2026091508272884600_cit1","doi-asserted-by":"publisher","first-page":"419","DOI":"10.1016\/j.foodchem.2018.07.034","article-title":"Black goji as a potential source of natural color in\na wide pH range","volume":"269","author":"Tang","year":"2018","journal-title":"Food Chem."},{"key":"2026091508272884600_cit2","doi-asserted-by":"publisher","first-page":"802","DOI":"10.31024\/ajpp.2018.4.6.13","article-title":"Use of ethanolic extract of Lantana camara L. flowers\nas pH indicator","volume":"4","author":"Patmas","year":"2018","journal-title":"Asian J. Pharm. Pharmacol."},{"key":"2026091508272884600_cit3","doi-asserted-by":"publisher","first-page":"1361779","DOI":"10.1080\/16546628.2017.1361779","article-title":"Anthocyanidins\nand anthocyanins: colored pigments as food, pharmaceutical ingredients,\nand the potential health benefits","volume":"61","author":"Khoo","year":"2017","journal-title":"Food Nutr.\nRes."},{"key":"2026091508272884600_cit4","doi-asserted-by":"publisher","first-page":"28","DOI":"10.1021\/jf049018+","article-title":"Insulin\nsecretion by bioactive anthocyanins and anthocyanidins present in\nfruits","volume":"53","author":"Jayaprakasam","year":"2005","journal-title":"J. Agric. Food Chem."},{"key":"2026091508272884600_cit5","doi-asserted-by":"publisher","first-page":"920","DOI":"10.1111\/1750-3841.14490","article-title":"Delphinidin Chloride\nand Its Hydrolytic Metabolite Gallic Acid Promote Differentiation\nof Regulatory T cells and Have an Anti-inflammatory Effect on the\nAllograft Model","volume":"84","author":"Hyun","year":"2019","journal-title":"J. Food Sci."},{"key":"2026091508272884600_cit6","doi-asserted-by":"publisher","first-page":"86","DOI":"10.1016\/j.phymed.2018.09.029","article-title":"Effects of malvidin, cyanidin and delphinidin on human\nadipose mesenchymal stem cell differentiation into adipocytes, chondrocytes\nand osteocytes","volume":"53","author":"Saulite","year":"2019","journal-title":"Phytomedicine"},{"key":"2026091508272884600_cit7","first-page":"960","article-title":"A piezoelectric\norganic surface to control bacterial adhesion and growth","volume-title":"European Medical and Biological Engineering Confernce,\nNordic-Baltic Conference on Biomedical Engineering and Medical Physics","author":"Moreddu","year":"2018"},{"key":"2026091508272884600_cit8","doi-asserted-by":"publisher","first-page":"875","DOI":"10.2147\/opth.s109708","article-title":"The Sensimed\nTriggerfish contact lens sensor: efficacy, safety, and patient perspectives","volume":"11","author":"Dunbar","year":"2017","journal-title":"Clin. Ophthalmol."},{"key":"2026091508272884600_cit9","doi-asserted-by":"publisher","first-page":"11","DOI":"10.1016\/j.ijbiomac.2017.05.149","article-title":"Effect of blueberry\nagro-industrial waste addition to corn starch-based films for the\nproduction of a pH-indicator film","volume":"104","author":"Luchese","year":"2017","journal-title":"Int. J. Biol.\nMacromol."},{"key":"2026091508272884600_cit10","doi-asserted-by":"publisher","first-page":"492","DOI":"10.1016\/j.lwt.2017.03.006","article-title":"pH-sensitive films containing anthocyanins\nextracted from black bean seed coat and red cabbage","volume":"80","author":"Prietto","year":"2017","journal-title":"LWT--Food Sci. Technol."},{"key":"2026091508272884600_cit11","doi-asserted-by":"publisher","first-page":"2735","DOI":"10.1002\/jsfa.8769","article-title":"Ultrafine fibers of zein and anthocyanins\nas natural pH indicator","volume":"98","author":"Prietto","year":"2018","journal-title":"J. Sci. Food Agric."},{"key":"2026091508272884600_cit12","doi-asserted-by":"publisher","first-page":"180","DOI":"10.1016\/j.foodhyd.2014.05.014","article-title":"Active chitosan\/PVA films with anthocyanins\nfrom Brassica oleraceae (Red Cabbage) as Time\u2013Temperature Indicators\nfor application in intelligent food packaging","volume":"43","author":"Pereira","year":"2015","journal-title":"Food Hydrocolloids"},{"key":"2026091508272884600_cit13","doi-asserted-by":"publisher","first-page":"122","DOI":"10.1016\/j.foodchem.2016.09.050","article-title":"Intelligent pH indicator film composed of agar\/potato starch and\nanthocyanin extracts from purple sweet potato","volume":"218","author":"Choi","year":"2017","journal-title":"Food Chem."},{"key":"2026091508272884600_cit14","doi-asserted-by":"publisher","first-page":"193","DOI":"10.1016\/j.carbpol.2016.09.027","article-title":"Development of a colorimetric pH indicator based on\nbacterial cellulose nanofibers and red cabbage (Brassica oleraceae)\nextract","volume":"156","author":"Pourjavaher","year":"2017","journal-title":"Carbohydr. Polym."},{"key":"2026091508272884600_cit15","doi-asserted-by":"publisher","first-page":"1001","DOI":"10.1039\/b802662a","article-title":"Dietary\nphenolics: chemistry, bioavailability and effects on health","volume":"26","author":"Crozier","year":"2009","journal-title":"Nat. Prod. Rep."},{"key":"2026091508272884600_cit16","doi-asserted-by":"publisher","first-page":"348","DOI":"10.1016\/j.exer.2005.12.019","article-title":"Comparative assessment of distribution of blackcurrant\nanthocyanins in rabbit and rat ocular tissues","volume":"83","author":"Matsumoto","year":"2006","journal-title":"Exp. Eye Res."},{"key":"2026091508272884600_cit17","doi-asserted-by":"publisher","first-page":"3560","DOI":"10.1021\/jf034132y","article-title":"Stimulatory effect of cyanidin 3-glycosides\non the regeneration of rhodopsin","volume":"51","author":"Matsumoto","year":"2003","journal-title":"J. Agric.\nFood Chem."},{"key":"2026091508272884600_cit18","doi-asserted-by":"publisher","first-page":"359","DOI":"10.1080\/15569527.2018.1471698","article-title":"The intraocular\nstaining potential of anthocyanins and their retinal biocompatibility:\na preclinical study","volume":"37","author":"Chuang","year":"2018","journal-title":"Cutaneous Ocul. Toxicol."},{"key":"2026091508272884600_cit19","doi-asserted-by":"publisher","first-page":"301","DOI":"10.1001\/archopht.1981.03930010303017","article-title":"Normal Human Tear\nPh by Direct Measurement","volume":"99","author":"Abelson","year":"1981","journal-title":"Arch. Ophthalmol."},{"key":"2026091508272884600_cit20","doi-asserted-by":"publisher","first-page":"251","DOI":"10.1016\/0014-4835(90)90209-d","article-title":"The Ph in the Precorneal Tear Film and under a Contact-Lens\nMeasured with a Fluorescent-Probe","volume":"50","author":"Chen","year":"1990","journal-title":"Exp. Eye\nRes."},{"key":"2026091508272884600_cit21","doi-asserted-by":"publisher","first-page":"32","DOI":"10.1111\/j.1755-3768.1985.tb06834.x","article-title":"Tear pH after instillation of buffer\nin vivo","volume":"63","author":"Norn","year":"1985","journal-title":"Acta Ophthalmol."},{"key":"2026091508272884600_cit22","doi-asserted-by":"publisher","first-page":"168","DOI":"10.1007\/bf02215658","article-title":"Human precorneal tear film pH measured by microelectrodes","volume":"218","author":"Fischer","year":"1982","journal-title":"Graefes Arch. Clin. Exp. Ophthalmol."},{"key":"2026091508272884600_cit23","doi-asserted-by":"publisher","first-page":"75","DOI":"10.1111\/j.1755-3768.1990.tb01653.x","article-title":"Tear Buffering in Contact-Lens Wearers","volume":"68","author":"Carney","year":"1990","journal-title":"Acta Ophthalmol."},{"key":"2026091508272884600_cit24","doi-asserted-by":"publisher","first-page":"215","DOI":"10.1016\/0378-5173(84)90164-9","article-title":"Effect of Ph and\nBuffer on the Precorneal Disposition and Ocular Penetration of Pilocarpine\nin Rabbits","volume":"19","author":"Ahmed","year":"1984","journal-title":"Int. J. Pharm."},{"key":"2026091508272884600_cit25","doi-asserted-by":"publisher","first-page":"866","DOI":"10.1016\/s0002-9394(14)75203-1","article-title":"Alkaline Tear Ph\nin Ocular Rosacea","volume":"90","author":"Abelson","year":"1980","journal-title":"Am. J. Ophthalmol."},{"key":"2026091508272884600_cit26","doi-asserted-by":"publisher","first-page":"1981","DOI":"10.1021\/pr0501620","article-title":"Glycomics analyses\nof tear fluid for the diagnostic detection of ocular rosacea","volume":"4","author":"An","year":"2005","journal-title":"J. Proteome Res."},{"key":"2026091508272884600_cit27","doi-asserted-by":"publisher","first-page":"134","DOI":"10.1111\/j.1755-3768.1987.tb06990.x","article-title":"Ph Changes of the\nTear Fluid in the Conjunctival Sac during Postoperative Inflammation\nof the Human-Eye","volume":"65","author":"Thygesen","year":"1987","journal-title":"Acta Ophthalmol."},{"key":"2026091508272884600_cit28","doi-asserted-by":"publisher","first-page":"11433","DOI":"10.1039\/c9ra00601j","article-title":"Contact lenses for continuous corneal temperature monitoring","volume":"9","author":"Moreddu","year":"2019","journal-title":"RSC Adv."},{"key":"2026091508272884600_cit29","doi-asserted-by":"publisher","first-page":"1900368","DOI":"10.1002\/adhm.201900368","article-title":"Contact\nlens technology: from fundamentals to applications","volume":"8","author":"Moreddu","year":"2019","journal-title":"Adv. Healthcare Mater."},{"key":"2026091508272884600_cit30","doi-asserted-by":"publisher","first-page":"261","DOI":"10.1146\/annurev-food-030216-025923","article-title":"Natural colorants:\nfood colorants from natural sources","volume":"8","author":"Sigurdson","year":"2017","journal-title":"Annu. Rev.\nFood Sci. Technol."},{"key":"2026091508272884600_cit31","doi-asserted-by":"publisher","first-page":"180","DOI":"10.1111\/1541-4337.12244","article-title":"Natural pigments: stabilization methods\nof anthocyanins for food applications","volume":"16","author":"Cortez","year":"2017","journal-title":"Compr.\nRev. Food Sci. Food Saf."},{"key":"2026091508272884600_cit32","doi-asserted-by":"publisher","first-page":"923","DOI":"10.1016\/s0031-9422(03)00438-2","article-title":"Analysis and biological activities\nof anthocyanins","volume":"64","author":"Kong","year":"2003","journal-title":"Phytochemistry"},{"key":"2026091508272884600_cit33","doi-asserted-by":"publisher","first-page":"8461","DOI":"10.1021\/ja00468a015","article-title":"Chemistry of anthocyanin pigments. 2. Kinetic and thermodynamic\nstudy of proton transfer, hydration, and tautomeric reactions of malvidin\n3-glucoside","volume":"99","author":"Brouillard","year":"1977","journal-title":"J. Am. Chem. Soc."},{"key":"2026091508272884600_cit34","doi-asserted-by":"crossref","DOI":"10.1002\/9780470015902.a0001909.pub2","article-title":"Anthocyanins","volume-title":"eLS 2010","author":"Andersen","year":"2010"},{"key":"2026091508272884600_cit35","doi-asserted-by":"publisher","first-page":"012047","DOI":"10.1088\/1757-899x\/193\/1\/012047","article-title":"The Effect of pH and Color Stability of Anthocyanin\non Food Colorant","volume":"193","author":"Wahyuningsih","year":"2017","journal-title":"IOP Conf. Ser.: Mater. Sci.\nEng."},{"key":"2026091508272884600_cit36","unstructured":"Gordon, S. I.\n          \n          Hydrophilic contact lens. U.S. Patent 4,123,407A, 1978."},{"key":"2026091508272884600_cit37","first-page":"2388","article-title":"Chemical Characterization of 1\u2013DAY ACUVUE MOIST (tm) and 1\u2013DAY\nACUVUE Contact Lenses","volume":"47","author":"Sheardown","year":"2006","journal-title":"Invest. Ophthalmol. Visual\nSci."},{"key":"2026091508272884600_cit38","doi-asserted-by":"crossref","unstructured":"Moezzi, A.; Varikooty, J.; Schulze, M.; Ngo, W.; Lorenz, K. O.; Boree, D.; Jones, L. In  Open-eye corneal swelling\nwith etafilcon A with PVP daily disposable limbal ring and clear hydrogel\ncontact lenses compared to no lens wear, Poster at BCLA Clinical Conference,\nBirmingham, U.K., 2014.","DOI":"10.1016\/j.clae.2014.11.025"}],"container-title":["ACS Omega"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/acsomega.9b02638","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/acsodf\/article-pdf\/4\/26\/21792\/67669079\/acsomega.9b02638.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/acsodf\/article-pdf\/4\/26\/21792\/67669079\/acsomega.9b02638.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T12:49:31Z","timestamp":1789476571000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/acsodf\/article\/4\/26\/21792\/608577\/Anthocyanin-Functionalized-Contact-Lens-Sensors"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,12,12]]},"references-count":38,"journal-issue":{"issue":"26","published-online":{"date-parts":[[2019,12,12]]},"published-print":{"date-parts":[[2019,12,24]]}},"URL":"https:\/\/doi.org\/10.1021\/acsomega.9b02638","relation":{},"ISSN":["2470-1343"],"issn-type":[{"value":"2470-1343","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,12,12]]}}}