| dc.description.abstract | Graphene is a two-dimensional (2D) material composed only of carbon atoms, which
has been widely studied due to its electrical, mechanical and optical properties. The
combination of this material with some characterization techniques has achieved important
achievements, especially in the development of biosensors. However, the use of graphene
for such purposes begins with the challenge of understanding all the properties of this
material in the presence of liquid media.
Thus, the first proposal of this thesis is to improve the understanding of the electrical
properties of graphene, when it becomes at the air/water interface. We conducted this study
by building a device that allowed us to study the interaction of graphene suspended over
water, that is, without the presence of substrates. We observed that the abrupt decrease
in the resistivity of suspended graphene in the presence of water is electromechanical in
nature, with a load transfer effect of much less magnitude, if any, than mechanical effects.
This result not only clears up some basic scientific enigmas (transferring charge from water
to graphene), but it also unlocks new applications for small fluid hybrid systems.
In a second approach, we manufacture a micro-hole platform for analyzing biomaterials
in liquid environments with nanoscale infrared spectroscopy. In this second work, using
the graphene / liquid interface, together with the SINS technique (Synchrotron Infrared
Nano-spectroscopy), we obtain the infrared “fingerprint” of fluids, biological and chemical,
such as Dimethyl Sulfoxide (DMSO), Potassium dihydrogen phosphate (KH2PO4) and
pyrenobutanoic acid succinimidyl ester (PBSE). In addition, we demonstrate the nanospectroscopy of fragments of human serum albumin (HSA) in water with a clear view of the
spectral signatures of proteins and their secondary structures through the vibrational
response of the amide bands I-II. | |
