Quantum dot effects upon the interaction between porphyrins and phospholipids in cell membrane models

Abstract

This study employed surface pressure isotherms and spectroscopic techniques to investigate the effect of quantum dots on the interaction between porphyrins and phospholipids using Langmuir monolayers and Langmuir-Blodgett films formed from negatively charged DMPA (the sodium salt of dimyristoyl-sn-glycero-phosphatidyl acid) and zwitterionic DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) as cell membrane models in the presence of 5,10,15,20-tetrakis(4-N-tetradecyl-pyridyl) porphyrin (TMPyP), 5,10,15,20-tetrakis(p-sulfonato-phenyl) porphyrin (TPPS4) and PEG-coated CdSe/ZnS quantum dots (QD). The porphyrins present at the monolayer subphase affected the organization of the lipids at the air/liquid interface, as shown by the changes in the surface pressure-surface area isotherms. QDs enhanced the interaction of TMPyP with DMPA, improving their transference from the liquid monolayers to solid supports. A higher amount of TMPyP was transferred to DMPA-Langmuir-Blodgett films when the QDs were present in the subphase as evidenced by the UV-Vis data. For DPPC the surface effects due to the presence of QDs are less evident.

Evolution of Nanoflowers and Nanospheres of Zinc Bisporphyrinate Tweezers at the Air/Water Interface

“…On the basis of molecular structure modeling optimized using Gaussian 09 program as shown in Scheme b, considering that the hydrophilic diamide group is attached to the surface and peripheral phenyl group of macrocyclic porphyrins formed an extended feet on water surface, the molecular area of [Zn 2 -1] is estimated to be 2.2 nm 2 , which is much larger than 0.96 nm 2 . This indicated that the two zinc bisporphyrins took up an inclined orientation arrangement and formed multilayer or nonmonolayer aggregates at the air/water interface …”

“…This indicated that the two zinc bisporphyrins took up an inclined orientation arrangement and formed multilayer or nonmonolayer aggregates at the air/water interface. 52 Atomic Force Microscopy Images of the One-Layer LB Films of [Zn 2 -1]. To further investigate the self-assembling process of the bisporphyrins at the air/water interface, the spreading films of [Zn 2 -1] or [Zn 2 -2] were transferred onto the clean mica surface using a vertical lifting method with an uptake speed of 1 mm•min −1 and their atomic force microscopy (AFM) images were analyzed.…”