Competitive Adsorption of Dopamine and Rhodamine 6G on the Surface of Graphene Oxide

Abstract

Competitive adsorption-desorption behavior of popular fluorescent labeling and bioanalyte molecules, Rhodamine 6G (R6G) and dopamine (DA), on a chemically heterogeneous graphene oxide (GO) surface is discussed in this study. Individually, R6G and DA compounds were found to adsorb rapidly on the surface of graphene oxide as they followed the traditional Langmuir adsorption behavior. FTIR analysis suggested that both R6G and DA molecules predominantly adsorb on the hydrophilic oxidized regions of the GO surface. Thus, when R6G and DA compounds were adsorbed from mixed solution, competitive adsorption was observed around the oxygen-containing groups of GO sheets, which resulted in partial desorption of R6G molecules from the surface of GO into the solution. The desorbed R6G molecules can be monitored by fluorescence change in solution and was dependent on the DA concentration. We suggest that the efficient competitive adsorption of different strongly bound bioanalytes onto GO-dye complex can be used for the development of sensitive and selective colorimetric biosensors.

High structure stability and outstanding adsorption performance of graphene oxide aerogel supported by polyvinyl alcohol for waste water treatment

“…The Langmuir adsorption constant band the maximum adsorption amount x m (mg/g) can be estimated from the linear fitting curve (Fig. 5d) of 1/q e vs. 1/C e according to the Langmuir adsorption model [56,57]: where q e is the equilibrium adsorption amount of dyes (mg/g), C e is the equilibrium concentration in the aqueous solution (mg/mL). And then, the free energy of adsorption ΔG θ (kJ/mol) can be estimated according to the following equation [58]:…”

“…Consequently, x m and ΔG θ are estimated to be 127.5 mg/g and − 3.82 kJ/mol, respectively. The negative low value of ΔG θ indicates that the adsorption for dyes is a spontaneous process and it is controlled by relatively weak physical interaction between the aerogel and dye molecules [56]. Moreover, the adsorption amount (mg/g) of different aerogels for CR and MB at a certain dye solution concentration are calculated and shown in Fig.…”

Laser induced fluorescence spectroscopy of various carbon nanostructures (GO, G and nanodiamond) in Rd6G solution

“…This event is very useful in the optical detection of biomolecules [50]. Graphene oxide, with oxygen-containing groups such as -COOH, -CO, and -OH at the surface, gains the advantage of hydrophilicity, high surface activity and significant fluorescence quenching property [51]. Figure 4 illustrates the schematic atomic structure of GO/G/ND.…”

“…Figure 7 illustrates the sets of LIF spectra due to the addition of G/GO/ND densities (ranging 0-50 μgmL −1 ) in 40 μM Rd6G solution. Adding slight amount of G/GO nanostructures below 50 μgmL −1 , the emission spectra exhibit a faint blue shift, likely due to the chemical coupling between G/GO and Rd6G molecules as (G/GO + Rd6G) complex [28,30,51]. Moreover, Fig.…”

Narrow Bandwidth Top-Emitting OLEDs Designed for Rhodamine 6G Excitation in Biological Sensing Applications

“…Optical sensors that are based on the stimulation of oxygen-sensitive dyes or derivatives of the xanthene group like R6G dyes are still in the focus of continuous effort to enhance the sensors accuracy, reliability, detection limit, operational lifetime or to reduce their cost and size [2]. For these requirements, organic sensors can offer a wide range of advantages such as low cost production, versatility, applicability, disposability, flexibility and a compact size of the whole architecture [2,11], hence being very attractive for medical [16], biological [17][18][19][20] environmental [21,22] and industrial applications [17].…”