Jessica Zofie Kubicek-Sutherland

There have been tremendous advances in nanotechnology. Recently, the use of nanoparticles has expanded to applications including materials, packaging, energy, and medical uses, such as drug delivery, diagnostics, and therapeutics. The biomedical uses of nanoparticles are particularly promising because of their ability to reach and target various sites and organs. However, some nanoparticles can be composed of toxic materials or are limited by issues of biodistribution and bioaccumulation, which have hampered their use in biomedicine. The copolymer poly(lactic-co-glycolic acid) (PLGA) has gained use in biomedical applications as a delivery system because it is considered biocompatible and can be formulated with controlled degradation in physiological environments. The United States Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have approved various PLGA particle formulations as therapeutic delivery vehicles. Despite recent advances in PLGA nanoparticle formulations, residual stabilizing molecules, inconsistent preparations, and batch-to-batch variations can lead to toxicity. There is a need for robust methods to evaluate the biological toxicity of PLGA nanoparticles both in vitro and in vivo, as well as studies on their potential environmental impacts. A systematic evaluation and detailed understanding of how PLGA and the other components used to help formulate this copolymer into a nanoparticle delivery vehicle is crucial for assessing and mitigating any potential harmful effects to humans and the environment.

The successful isolation of mycolactone in a laboratory or from a clinical sample relies on proper handling and storage of the toxin. Mycolactone is a light-sensitive and an amphiphilic toxin produced by Mycobacterium ulcerans. The biochemistry of the toxin makes it unstable in aqueous matrices such as blood, which causes it to self-aggregate or present in complex with carrier molecules. This biochemistry also impacts the use of the toxin in vitro, in that it tends to aggregate and stick to substrates in an aqueous environment, which alters its physiological presentation and limits its availability in a sample. Glass materials (i.e., tubes, vials, syringes, plates) should be used when possible to avoid loss of mycolactone sticking to plastic surfaces. Dark containers such as amber vials or aluminum-foil wrapped tubes should be used to avoid photodegradation of the toxin upon exposure to light. Sample storage in organic solvents is ideal for mycolactone stability and recovery; however, this is not always amenable as multiple diagnostic assays might be performed on a single sample (such as PCR or ELISA). In these cases, samples can be stored in an aqueous solution containing a small amount of detergent to enhance recovery of the toxin, and in order to avoid aggregation. Therefore, the downstream manipulations should be carefully considered prior to sample collection and storage. Here we present considerations for the optimal handling and storage of mycolactone in order to obtain quality yield of the toxin for various research and diagnostic applications.