Adsorption of oligonucleotides on PMMA/PNIPAM core-shell latexes: polarity of the PNIPAM shell probed by fluorescence.
The adsorption of a rhodamine X labeled oligonucleotide composed of 25-mers of thymine (dT(25)-ROX) onto the thermosensitive shell of PMMA/PNIPAM core-shell latex particles was studied at 22 and 40 degrees C, below and above the T(VPT) (volume phase transition temperature) of the PNIPAM shell, respectively. The experimental binding isotherms were well fitted with the cooperative Hill model. The Hill coefficient is lower than 1 at both temperatures showing that the adsorption is anticooperative. The polarity of the shell was probed by both the lifetimes and solvatochromic shifts of the zwitterionic form of rhodamine X. For temperatures below the shell T(VPT) has a polarity similar to that of water, while for temperatures above the transition the polarity is equivalent to that of a water/dioxane mixture with 30% (v/v) water.
Centro de Química-Física Molecular, Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal.
T J V
TJ
Prazeres
A M
AM
Santos
J M G
JM
Martinho
A
A
Elaïssari
C
C
Pichot
D000180:Acrylic Resins / Q000737:chemistry*; D000327:Adsorption; D008027:Light; D015394:Molecular Structure; D009841:Oligonucleotides / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods; D013499:Surface Properties; D013696:Temperature
D000180:Acrylic Resins; D009841:Oligonucleotides; C052970:poly-N-isopropylacrylamide; D019904:Polymethyl Methacrylate