title: Unbinding forces and energies between a siRNA molecule and a dendrimer measured by force spectroscopy.
abstract: We have measured the intermolecular forces between small interference RNA (siRNA) and polyamidoamine dendrimers at the single molecular level. A single molecule force spectroscopy approach has been developed to measure the unbinding forces and energies between a siRNA molecule and polyamidoamine dendrimers deposited on a mica surface in a buffer solution. We report three types of unbinding events which are characterized by forces and free unbinding energies, respectively, of 28 pN, 0.709 eV; 38 pN, 0.722 eV; and 50 pN, 0.724 eV. These events reflect different possible electrostatic interactions between the positive charges of one or two dendrimers and the negatively charged phosphate groups of a single siRNA. We have evidence of a high binding affinity of siRNA towards polyamidoamine dendrimers that leads to a 45% probability of measuring specific unbinding events.
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, c/Sor Juana Ines de la Cruz 3, 28049 Madrid, Spain. r.garcia@csic.es.
authors.forename: Andra C
authors.initials: AC
authors.lastname: Dumitru
authors.forename: Elena T
authors.initials: ET
authors.lastname: Herruzo
authors.forename: Estrella
authors.initials: E
authors.lastname: Rausell
authors.forename: Valentin
authors.initials: V
authors.lastname: Ceña
authors.forename: Ricardo
authors.initials: R
authors.lastname: Garcia
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry*; D002021:Buffers; D050091:Dendrimers / Q000737:chemistry*; D006493:Heparin / Q000737:chemistry; D018625:Microscopy, Atomic Force; D011073:Polyamines / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000737:chemistry* / Q000378:metabolism; D013057:Spectrum Analysis; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D000538:Aluminum Silicates; D001672:Biocompatible Materials; D002021:Buffers; D050091:Dendrimers; C531249:Poly(amidoamine); D011073:Polyamines; D011108:Polymers; D034741:RNA, Small Interfering; D006493:Heparin; C041325:polyphenylene sulfide; C011934:mica