4-Morpholineethanesulfonic acid: properties and applications

General Description

4-Morpholineethanesulfonic acid (MES) is a versatile organic compound with several important properties. It is commonly used as a buffering agent and pH regulator in biochemical and molecular biology research. MES is chemically stable and exhibits low reactivity with other compounds under normal laboratory conditions. It is known for its mildness and compatibility with enzymes, making it a preferred choice in enzymatic studies. MES does not adversely affect enzyme activity or interfere with binding reactions in most cases. Overall, MES is an indispensable tool in various biological and biochemical applications. Additionally, MES is utilized in the separation and characterization of aluminum chlorohydrates (ACH) oligomers and in the development of colorimetric nanosensors for the quantitative detection of copper (II) and mercury (II) ions at nanomolar concentrations.

Figure 1. 4-Morpholineethanesulfonic acid

Properties

4-Morpholineethanesulfonic acid is a widely used organic compound with various properties and characteristics. It is commonly employed as a buffering agent and a pH regulator in biochemical and molecular biology research. MES possesses exceptional buffering capacity within a pH range of 5.5 to 6.7. This makes it suitable for maintaining a stable pH environment in biological assays and cell cultures. Its pKa value is approximately 6.1, indicating that MES can effectively resist pH changes in this specific range. One of the remarkable features of MES is its high water solubility. It readily dissolves in water, allowing for easy preparation of MES solutions at desired concentrations. Additionally, MES is chemically stable and exhibits low reactivity with other compounds under normal laboratory conditions. MES is known for its mildness and compatibility with enzymes, making it a preferred choice in enzymatic studies. It does not adversely affect enzyme activity or interfere with binding reactions in most cases. This property is crucial for experimental accuracy and reliability. In summary, 4-Morpholineethanesulfonic acid is a versatile compound with excellent buffering capacity, high water solubility, chemical stability, mildness, enzyme compatibility, and low toxicity. These properties make it an indispensable tool in various biological and biochemical applications. ¹

Applications

Separation and characterization of ACH

4-Morpholineethanesulfonic acid is utilized in the separation and characterization of aluminum chlorohydrates (ACH) oligomers. ACH finds wide-ranging applications in water treatment, catalysis, and antiperspirants. However, due to their tendency to depolymerize in solution when not in equilibrium, separating and quantifying the different polycations of ACH is challenging. To address this issue, we have successfully employed capillary electrophoresis with MES as a counter-ion in the background electrolyte. MES serves to stabilize the ACH oligomers during the electrophoretic process, resulting in highly repeatable and rapid separations. In order to optimize the separation of ACH oligomers, we conducted further investigations by varying the ionic strength, MES concentration, and pH of the background electrolyte. Through these experiments, we observed complex electrophoretic behavior for the separation of Al13, Al30, and Na+ ions. These optimized conditions allowed us to successfully separate samples that were challenging to analyze using other methods. The viability of this approach was validated, highlighting the effectiveness of using 4-morpholineethanesulfonic acid in the separation and characterization of ACH oligomers. ²

Development of colorimetric nanosensors

The application of 4-morpholineethanesulfonic acid can be used in the development of colorimetric nanosensors for the quantitative detection of copper (II) (Cu2+) and mercury (II) (Hg2+) ions at nanomolar concentrations. These nanosensors offer label-free and equipment-free detection capabilities. The Cu2+ nanosensor functions by promoting the growth of gold nanoparticles (AuNPs) through the reduction of chloroauric acid using MES. The presence of Cu2+ accelerates this redox process, leading to the rapid formation of a red solution containing dispersed and uniform spherical AuNPs. The properties of these AuNPs, particularly their surface plasmon resonance, contribute to the color change observed in the solution. On the other hand, the Hg2+ nanosensor produces a blue mixture consisting of aggregated and ill-defined AuNPs with varying sizes. This mixture exhibits a significantly enhanced Tyndall effect (TE) signal compared to the red solution of AuNPs. By utilizing a timer and a smartphone, the time taken to produce the red solution and the TE intensity of the blue mixture can be quantitatively measured. The performance of these nanosensors has been validated through the analysis of complex real water samples, including drinking water, tap water, and pond water, with acceptable recovery results ranging from 90.43% to 111.56%. ³

Reference

1. 4-Morpholineethanesulfonic acid. Echemi, 2018, CAS No:4432-31-9.

2. Ouadah N, Moire C, Brothier F, Kuntz JF, Deschaume O, Bartic C, Cottet H. Capillary electrophoresis for aluminum ion speciation: Optimized separation conditions for complex polycation mixtures. J Chromatogr A, 2018, 1552:79-86.

3. Hua F, Pan F, Yang J, Yan Y, Huang X, Yuan Y, Nie J, Wang H, Zhang Y. Quantitative colorimetric sensing of heavy metal ions via analyte-promoted growth of Au nanoparticles with timer or smartphone readout. Anal Bioanal Chem, 2023, 415(14):2705-2713.

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