Per-6-O-(tert-butyldimethylsilyl)cyclodextrins (TBDMS-CDs) in Langmuir monolayers: the importance of a spreading solvent in the preparation of LB layers suitable for sensor application.
Commercially available amphiphilic cyclodextrins, namely per-6-O-(tert-butyldimethylsilyl) alpha, beta and gamma cyclodextrins (TBDMS-alpha-, -beta-, and -gamma-CDs) were subjected to a thorough Langmuir monolayer characterization, using both traditional methods of surface manometry (pi/A isotherms, stability experiments) and modern micrometer/nanometer resolution (BAM, AFM) surface techniques. It has been found that inconsistent behavior regarding the isotherms reproducibility obtained upon compression of TBDMS-beta-CDs is due to the aggregation of the investigated molecules in chloroform and hexane, while good reproducibility ensured a mixed spreading solvent system of hexane/isopropanol 7:3 (v/v). Although the stability of films dropped from chloroform and hexane/isopropanol solvents below the equilibrium surface pressure (ESP) was comparable, pronounced differences were observed at pressures above ESP. The investigated TBDMS-CDs were successfully transferred onto cadmium stearate covered mica substrates. AFM images confirmed the presence of discontinuous multilayered films (10 nm heights) spread from chloroform versus monomolecular dispersion achieved in hexane/isopropanol.
Flasiński
Michał
M
Jagiellonian University, Faculty of Chemistry, Ingardena 3, 30-060 Kraków, Poland.
Broniatowski
Marcin
M
Romeu
Nuria Vila
NV
Dynarowicz-Łatka
Patrycja
P
Moreno
Amparo Gallardo
AG
Vilas
Antonio Mendez
AM
Martín
M Luisa González
ML
D019840:2-Propanol / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D002104:Cadmium / Q000737:chemistry; D002725:Chloroform / Q000737:chemistry; D003505:Cyclodextrins / Q000737:chemistry*; D004566:Electrodes; D006586:Hexanes / Q000737:chemistry; D008567:Membranes, Artificial; D015394:Molecular Structure; D010316:Particle Size; D015203:Reproducibility of Results; D012997:Solvents / Q000737:chemistry; D013228:Stearates / Q000737:chemistry; D013237:Stereoisomerism; D013499:Surface Properties
D000538:Aluminum Silicates; D003505:Cyclodextrins; D006586:Hexanes; D008567:Membranes, Artificial; D012997:Solvents; D013228:Stearates; D002104:Cadmium; D002725:Chloroform; D019840:2-Propanol; C011934:mica