{"id":{"repo_id":"soton","oai_identifier":"oai:eprints.soton.ac.uk:209093"},"canonical_url":"https://search.dev.ndltd.org/etd/soton/oai:eprints.soton.ac.uk:209093","repository":{"repo_id":"soton","name":"University of Southampton","base_url":"https://eprints.soton.ac.uk/cgi/oai2"},"display":{"title":"Surface functionalisation of encoded SU-8 microparticles and their uses in multiplexed suspension biological assays","abstract":"Recently, a novel diffractive-based encoded system has been developed for various multiplexed suspension biological assays. These microparticles, which are manufactured using photolithography of a commercial epoxy-based negative photoresist (SU-8), contain micrometre-sized diffractive elements and can encode millions of unique codes. In this thesis, the preparation and surface modification of different diffractive microparticles; the attachment of a range of biological molecules (e.g. proteins and peptides) onto the functionalised surfaces; and different on-bead analytical techniques for surface characterisation are described. From a thermodynamic study of a multiplexed immunoassay for immunoglobulins (Ig, MW ~150 kDa), the immobilised probe molecules exhibit high affinity (Kd = 9 ± 3 nM) and excellent specificity (S/N >36:1) for the target analytes. The suspension assay resembles solution-like reaction kinetics allowing detection of multiple target proteins in <20 min. The encoded microparticles can also be used for quantifying small proteins, such as cytokines (MW ~20 kDa). In a particle-based sandwich suspension immunoassay, human tumour necrosis factor-alpha (TNF-?) and interleukin 6 (IL-6) are detected and compared with conventional enzyme-linked immunosorbent assays (ELISA). Correlation coefficients (R2) for the two cytokines are found to be >0.96. Intra-assay variability (%CV) is determined to be <25%. The sensitivity of the multiplexed immunoassay, expressed as Lowest Detection Limit (LDL), is found to be 379 fM and 1.47 pM for TNF-? and IL-6 respectively, and are comparable to the corresponding ELISAs as demonstrated by the suppliers","abstract_html":"Recently, a novel diffractive-based encoded system has been developed for various multiplexed suspension biological assays. These microparticles, which are manufactured using photolithography of a commercial epoxy-based negative photoresist (SU-8), contain micrometre-sized diffractive elements and can encode millions of unique codes. In this thesis, the preparation and surface modification of different diffractive microparticles; the attachment of a range of biological molecules (e.g. proteins and peptides) onto the functionalised surfaces; and different on-bead analytical techniques for surface characterisation are described. From a thermodynamic study of a multiplexed immunoassay for immunoglobulins (Ig, MW ~150 kDa), the immobilised probe molecules exhibit high affinity (Kd = 9 ± 3 nM) and excellent specificity (S/N >36:1) for the target analytes. The suspension assay resembles solution-like reaction kinetics allowing detection of multiple target proteins in <20 min. The encoded microparticles can also be used for quantifying small proteins, such as cytokines (MW ~20 kDa). In a particle-based sandwich suspension immunoassay, human tumour necrosis factor-alpha (TNF-?) and interleukin 6 (IL-6) are detected and compared with conventional enzyme-linked immunosorbent assays (ELISA). Correlation coefficients (R2) for the two cytokines are found to be >0.96. Intra-assay variability (%CV) is determined to be <25%. The sensitivity of the multiplexed immunoassay, expressed as Lowest Detection Limit (LDL), is found to be 379 fM and 1.47 pM for TNF-? and IL-6 respectively, and are comparable to the corresponding ELISAs as demonstrated by the suppliers","abstract_has_math":false,"creators":["She, Joseph K."],"institution":"University of Southampton","degree_name":"Ph.D.","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Roach, Peter L."],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-10","date_published":"2011-10","updated_at":"2026-07-24T04:36:36Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Roach, Peter L."]},{"key":"dc:creator","label":"Author","values":["She, Joseph K."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-10-31"]},{"key":"dc:date.issued","label":"Date","values":["2011-10"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Chemistry (pre 2018 reorg)","Chemistry"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Southampton"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://eprints.soton.ac.uk/209093/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Ph.D."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://eprints.soton.ac.uk/209093/1/J_SHE_PHD_THESIS_2011.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Recently, a novel diffractive-based encoded system has been developed for various multiplexed suspension biological assays. These microparticles, which are manufactured using photolithography of a commercial epoxy-based negative photoresist (SU-8), contain micrometre-sized diffractive elements and can encode millions of unique codes. In this thesis, the preparation and surface modification of different diffractive microparticles; the attachment of a range of biological molecules (e.g. proteins and peptides) onto the functionalised surfaces; and different on-bead analytical techniques for surface characterisation are described. From a thermodynamic study of a multiplexed immunoassay for immunoglobulins (Ig, MW ~150 kDa), the immobilised probe molecules exhibit high affinity (Kd = 9 ± 3 nM) and excellent specificity (S/N >36:1) for the target analytes. The suspension assay resembles solution-like reaction kinetics allowing detection of multiple target proteins in <20 min. The encoded microparticles can also be used for quantifying small proteins, such as cytokines (MW ~20 kDa). In a particle-based sandwich suspension immunoassay, human tumour necrosis factor-alpha (TNF-?) and interleukin 6 (IL-6) are detected and compared with conventional enzyme-linked immunosorbent assays (ELISA). Correlation coefficients (R2) for the two cytokines are found to be >0.96. Intra-assay variability (%CV) is determined to be <25%. The sensitivity of the multiplexed immunoassay, expressed as Lowest Detection Limit (LDL), is found to be 379 fM and 1.47 pM for TNF-? and IL-6 respectively, and are comparable to the corresponding ELISAs as demonstrated by the suppliers"]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["Surface functionalisation of encoded SU-8 microparticles and their uses in multiplexed suspension biological assays"]}]}],"canonical_facts":{"dc:contributor.advisor":["Roach, Peter L."],"dc:creator":["She, Joseph K."],"dc:date":["2011-10-31"],"dc:date.issued":["2011-10"],"dc:description.abstract":["Recently, a novel diffractive-based encoded system has been developed for various multiplexed suspension biological assays. These microparticles, which are manufactured using photolithography of a commercial epoxy-based negative photoresist (SU-8), contain micrometre-sized diffractive elements and can encode millions of unique codes. In this thesis, the preparation and surface modification of different diffractive microparticles; the attachment of a range of biological molecules (e.g. proteins and peptides) onto the functionalised surfaces; and different on-bead analytical techniques for surface characterisation are described. From a thermodynamic study of a multiplexed immunoassay for immunoglobulins (Ig, MW ~150 kDa), the immobilised probe molecules exhibit high affinity (Kd = 9 ± 3 nM) and excellent specificity (S/N >36:1) for the target analytes. The suspension assay resembles solution-like reaction kinetics allowing detection of multiple target proteins in <20 min. The encoded microparticles can also be used for quantifying small proteins, such as cytokines (MW ~20 kDa). In a particle-based sandwich suspension immunoassay, human tumour necrosis factor-alpha (TNF-?) and interleukin 6 (IL-6) are detected and compared with conventional enzyme-linked immunosorbent assays (ELISA). Correlation coefficients (R2) for the two cytokines are found to be >0.96. Intra-assay variability (%CV) is determined to be <25%. The sensitivity of the multiplexed immunoassay, expressed as Lowest Detection Limit (LDL), is found to be 379 fM and 1.47 pM for TNF-? and IL-6 respectively, and are comparable to the corresponding ELISAs as demonstrated by the suppliers"],"dc:format":["text"],"dc:identifier.uri":["https://eprints.soton.ac.uk/209093/1/J_SHE_PHD_THESIS_2011.pdf"],"dc:publisher.department":["Chemistry (pre 2018 reorg)","Chemistry"],"dc:publisher.institution":["University of Southampton"],"dc:relation.isreferencedby":["https://eprints.soton.ac.uk/209093/"],"dc:title":["Surface functionalisation of encoded SU-8 microparticles and their uses in multiplexed suspension biological assays"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["Ph.D."]},"updated_at":"2026-07-24T04:36:36Z"}