iBB

Ana Margarida Rosa will be defending her PhD thesis in Biotechnology and Biosciences on Wednesday the 29th january 2020 (10:30 H, amphitheater PA-3, Mathematics Building). During the last years, and under the supervision of Miguel Prazeres from BERG-iBB and Pedro Paulo from CQE-IST, Ana developed a cellulose-based system for the colorimetric detection of nucleic acids by exploring the recognition of biotin-labeled DNA hybrids by anti-biotin antibodies immobilized through ZZ-CBM chimeric proteins. These fusions combine carbohydrate-binding modules (CBM) with affinity to cellulose and double Z domains (ZZ) that bind to IgG antibodies. The title of the thesis is “DNA recognition system on bioactive paper using fusions of carbohydrate-binding modules and IgG-binding Z domains”.

Nucleic acid testing requires skilled personnel and expensive instrumentation and are thus difficult to implement in low income settings. In a paper published in the Biotechnology Journal, researchers from BERG-iBB describe a method for the detection of oligonucleotides that combines cellulose microparticles with biomolecular recognition. Cellulose microparticles are made bioactive by anchoring anti-biotin antibodies via ZZ-CBM fusions that combine a carbohydrate binding module with the ZZ fragment of protein A. Samples are prepared by incubating DNA probes immobilized on gold nanoparticles (AuNP) with biotin-labeled targets and then mixed with bioactive microparticles. The presence of un-labelled targets could also be probed by introducing a second, biotinylated DNA probe. The target:probe-AuNP hybrids are mixed with and captured by the microparticles, which change color from white to red. With this methodology, diverse analytical applications can be envisaged based on “reader-free” testing. The work was performed in the context of the project CBM-X.