Model Systems for Evidencing the Mediator Role of Riboflavin in the UVA Cross-Linking Treatment of Keratoconus
Mihaela Monica Constantin,
Cătălina Gabriela Corbu,
Sorin Mocanu,
Elena Irina Popescu,
Marin Micutz,
Teodora Staicu,
Raluca Şomoghi,
Bogdan Trică,
Vlad Tudor Popa,
Aurica Precupas,
Iulia Matei,
Gabriela Ionita
Affiliations
Mihaela Monica Constantin
Oftaclinic Clinic, Bd. Marasesti 2B, 040254 Bucharest, Romania
Cătălina Gabriela Corbu
Oftaclinic Clinic, Bd. Marasesti 2B, 040254 Bucharest, Romania
Sorin Mocanu
“Ilie Murgulescu” Institute of Physical Chemistry of the Romanian Academy, Splaiul Independentei 202, 060021 Bucharest, Romania
Elena Irina Popescu
“Ilie Murgulescu” Institute of Physical Chemistry of the Romanian Academy, Splaiul Independentei 202, 060021 Bucharest, Romania
Marin Micutz
Department of Physical Chemistry, Faculty of Chemistry, University of Bucharest, Bd. Regina Elisabeta 4-12, 030018 Bucharest, Romania
Teodora Staicu
Department of Physical Chemistry, Faculty of Chemistry, University of Bucharest, Bd. Regina Elisabeta 4-12, 030018 Bucharest, Romania
Raluca Şomoghi
Chemistry Department, Faculty of Petroleum Technology and Petrochemistry, Petroleum-Gas University of Ploiesti, Bd. Bucuresti 39, 100680 Ploiesti, Romania
Bogdan Trică
Department of Bioresources, National Institute for Research & Development in Chemistry and Petrochemistry—ICECHIM, Splaiul Independentei nr. 202, Sector 6, 060021 Bucharest, Romania
Vlad Tudor Popa
“Ilie Murgulescu” Institute of Physical Chemistry of the Romanian Academy, Splaiul Independentei 202, 060021 Bucharest, Romania
Aurica Precupas
“Ilie Murgulescu” Institute of Physical Chemistry of the Romanian Academy, Splaiul Independentei 202, 060021 Bucharest, Romania
Iulia Matei
“Ilie Murgulescu” Institute of Physical Chemistry of the Romanian Academy, Splaiul Independentei 202, 060021 Bucharest, Romania
Gabriela Ionita
“Ilie Murgulescu” Institute of Physical Chemistry of the Romanian Academy, Splaiul Independentei 202, 060021 Bucharest, Romania
Riboflavin under UVA radiation generates reactive oxygen species (ROS) that can induce various changes in biological systems. Under controlled conditions, these processes can be used in some treatments for ocular or dermal diseases. For instance, corneal cross-linking (CXL) treatment of keratoconus involves UVA irradiation combined with riboflavin aiming to induce the formation of new collagen fibrils in cornea. To reduce the damaging effect of ROS formed in the presence of riboflavin and UVA, the CXL treatment is performed with the addition of polysaccharides (dextran). Hyaluronic acid is a polysaccharide that can be found in the aqueous layer of the tear film. In many cases, keratoconus patients also present dry eye syndrome that can be reduced by the application of topical solutions containing hyaluronic acid. This study presents physico-chemical evidence on the effect of riboflavin on collagen fibril formation revealed by the following methods: differential scanning microcalorimetry, rheology, and STEM images. The collagen used was extracted from calf skin that contains type I collagen similar to that found in the eye. Spin trapping experiments on collagen/hyaluronic acid/riboflavin solutions evidenced the formation of ROS species by electron paramagnetic resonance measurements.
