Preparation and Evaluation of Polymer-Based Ultrasound Gel and Its Application in Ultrasonography

Abstract

Ultrasound imaging is a widely used technique in every health care center and hospital. Ultrasound gel is used as a coupling medium in all ultrasound procedures to replace air between the transducer and the patient's skin, as ultrasound waves have trouble in traveling through air. This research was performed to formulate an inexpensive alternative to commercially available ultrasound gel as it is expensive and imported from other countries. Different formulations with different concentrations of carbopol 980 (CAR 980) and methylparaben were prepared with natural ingredients such as aloe vera gel and certain available chemicals that have no harmful effects on the skin. To justify the efficiency of the formulations; necessary physicochemical characteristics such as visual clarity, homogeneity, transparency, skin irritation, antibacterial activity, pH, stability, spreadability, conductivity, acoustic impedance, viscosity, and cost were evaluated. Moreover, a comparison study was also conducted with commercially available ultrasound gel that was utilized as a control. All samples showed excellent transparency and no microbial growth. S1 was the only formulation that met all of the requirements for commercial ultrasound gel and produced images that were similar to those produced by commercial ultrasound gel. So, this formulation could be used as an alternative to expensive commercial ultrasound gel for taking images in hospitals and medical centers.

Keywords: CAR 980; aloe vera; methylparaben; ultrasonography; ultrasound gel.

Figure 1

Chemical structure of a monomeric unit of acrylic acid in a carbomer polymer.

Figure 2

Schematic diagram of the experimental setup.

Figure 3

Visual inspection of all samples.

Figure 4

Transmittance of all formulations (S1, S2, S3, …, S9), along with commercial gel (CG) in the visible range.

Figure 5

An increase in the concentration of triethanolamine was observed with an increase in the polymer (CAR 980) concentration to attain the pH of all formulations between 7 and 7.4.

Figure 6

During the study period of 24 h, no redness, edema, irritation, or any other negative effect was observed.

Figure 7

Dynamic viscosity (Pa.s) of all formulations when compared to commercial gel at different shear rates (1/s).

Figure 8

Nutrient agar plates showing zones of inhibition of all formulations along with commercial gel (CG), blank sample (S0), and control antibacterial Ciprofloxacin (+) against Gram-negative bacteria (Escherichia coli) after an incubation period of 24 h at 37 °C.

Figure 9

Ultrasound image of the right kidney produced (a) without any conductive medium, (b) when a selected formulation (S1) was applied to the skin, and (c) when a commercial gel (CG) was applied to the skin.

Figure 10

(a) Aloe vera plant, Aloe barbadensis, (b) washed aloe vera leaves, and (c) natural aloe vera gel.

Figure 11

Flowchart for the synthesis of carbopol based ultrasound gel formulations.