Unravelling the Absence of Testosterone Peak in Niosomes Using DSC; Insights from FTIR and HRTEM Investigations

Testosterone is one of the important hormones involved in various physiological activities including muscle growth, bone density, and libido. In this regard, delivery through niosomes may have potential advantages concerning its bioavailability and stability. Niosomes are vesicles based on non-ionic surfactants, an effective drug delivery system because of the encapsulation of different active pharmaceutical ingredients such as, hydrophilic, hydrophobics, and amphiphilic. In this work, differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and high-resolution transmission electron microscopy (HRTEM) were employed for the characterization of interactions and testosterone encapsulation in the fabricated niosome formulations. The main purpose of the work is to explain the absence of testosterone peaks in DSC spectra after the formulation of niosomes. Niosomes were prepared by dissolving 1% testosterone powder and different amounts of span60 powder, tween60 semisolid, and cholesterol powder via a modified solvent evaporation method. Besides the various plausible explanations associated with the testosterone peak changes, the few most important ones are solid-state transitions, interaction of the components via hydrogen bonding and van der Waals forces, encapsulation of testosterone, and dilution effect. These solid-state transitions might be polymorphic or transformation to the amorphous state from crystalline, which was also substantiated by the HRTEM images showing the crystalline structure at the center surrounded by an amorphous area. The FTIR data confirmed the testosterone encapsulation within the niosomes based on a chemical structure and functional groups. This analysis highlights the potential of designing stable niosome formulations for testosterone using different ingredients, facilitating its application in nanotechnology using different analysis techniques.