Ritort Farran, FèlixMihardja, S.Smith, S.B.Bustamante, C.J.2019-06-072019-06-072006-03-220031-9007https://hdl.handle.net/2445/134787When mixed together, DNA and polyaminoamide dendrimers form fibers that condense into a compact structure. We use optical tweezers to pull condensed fibers and investigate the decondensation transition by measuring force-extension curves (FECs). A characteristic force plateau (around 10 pN) and hysteresis between the pulling and relaxation cycles are observed for different dendrimer sizes, indicating the existence of a first-order transition between two phases (condensed and extended) of the fiber. Upon salt variation FECs change noticeably confirming that electrostatic forces drive the condensation transition. We propose a simple model for the decondensing transition that qualitatively reproduces the FECs and which is confirmed by atomic force microscopy images.4 p.application/pdfeng(c) American Physical Society, 2006CondensacióExperimentsCondensationExperimentsinfo:eu-repo/semantics/article6025142019-06-07info:eu-repo/semantics/openAccess