title: Several approaches for vitamin D determination by surface plasmon resonance and electrochemical affinity biosensors.
abstract: This work has been focused on the development of novel optical (Surface Plasmon Resonance) and electrochemical based biosensors for the determination of 25-OH vitamin D (25OHD) which is an important factor involved in avoiding both skeletal damage and a variety of pathological conditions, and to evaluate their potential use in clinical practice. Different approaches to the determination of vitamin D using affinity based biosensors, are described herein; firstly, an immunosensor based on SPR transduction was realized for direct determination of vitamin D, obtaining a LOD of 2 μg/ml which unfortunately is too far from the needs in clinical analysis. In order to enhance the sensitivity, the vitamin D was modified with gold nanoparticles (AuNPs): the binding of 25OHD with AuNPs determines the amplification of SPR signal, allowing to lower the LOD down to 1 μg/ml, doubling the sensitivity. An alternative SPR method, based on the indirect determination of vitamin D by means of Vitamin D Binding Protein (VDBP), led to a further sensitivity increase reaching a LOD of 45 ng/ml which is really close to the fixed accomplishment. Finally, an electrochemical transduced biosensor has been realized, based on the reaction of vitamin D with 4-ferrocenylmethyl-1,2,4-triazoline-3,5-dione (FMTAD): once derivatized, the determination of 25OHD was possible in the range 20-200 ng/ml with a LOD of 10 ng/ml. The latter proposed system fits the requirement of determining vitamin D in a concentration range which is of significance for clinical applications; moreover, since a screen printed electrode has been used, this opens the possibility to miniaturize the sensor and developing a portable and easy-to-automate point-of-care testing device. The proposed devices provide an improvement with respect to traditional methods that are time and reagents consuming and require radioactive compounds, pretreatment procedures and expensive instrumentation.
authors.affiliation: Department of Chemistry and Drug Technologies, Sapienza University of Rome, Piazzale Aldo Moro, 5-00185 Rome, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Carlucci
authors.forename: Gabriele
authors.initials: G
authors.lastname: Favero
authors.forename: Cristina
authors.initials: C
authors.lastname: Tortolini
authors.forename: Massimo
authors.initials: M
authors.lastname: Di Fusco
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Romagnoli
authors.forename: Salvatore
authors.initials: S
authors.lastname: Minisola
authors.forename: Franco
authors.initials: F
authors.lastname: Mazzei
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D003217:Conductometry / Q000295:instrumentation*; D004563:Electrochemistry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007118:Immunoassay / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014807:Vitamin D / Q000032:analysis*
chemical_list: D014807:Vitamin D