In recent decades there has been
growing interest of material chemists
in the successful development of functional materials for drug delivery,
tissue engineering, imaging, diagnosis, theranostic, and other biomedical
applications with advanced nanotechnology tools. The efficacy and
safety of functional materials are determined by their pharmacological,
toxicological, and immunogenic effects. It is essential to consider
all degradation pathways of functional materials and to assess plausible
intermediates and final products for quality control. This review
provides a brief insight into chemical degradation mechanisms of functional
materials like oxidation, photodegradation, and physical and enzymatic
degradation. The intermediates and products of degradation were confirmed
with analytical methods such as proton nuclear magnetic resonance
(1H NMR), gel permeation chromatography (GPC), UV–vis
spectroscopy (UV–vis), infrared spectroscopy (IR), differential
scanning calorimetry (DSC), mass spectroscopy, and other sophisticated
analytical methods. These analytical methods are also used for regulatory,
quality control, and stability purposes in industry. The assessment
of degradation is important to predetermine the behavior of functional
materials in specific storage conditions and can be relevant to their
behavior during in vivo applications. Another important aspect is
the evaluation of the toxicity of functional materials. Toxicity can
be accessed with various methods using in vitro, in vivo, ex vivo,
and in silico models. In vitro cell culture methods are used to determine
mitochondrial damage, reactive oxygen species, stress responses, and
cellular toxicity. In vitro cellular toxicity can be measured by MTT
assay, LDH leakage assay, and hemolysis. In vivo studies are performed
using various animal models involving zebrafish, rodents (mice and
rats), and nonhuman primates. Ex vivo studies are also used for efficacy
and toxicity determinations of functional materials like ex vivo potency
assay and precision-cut liver slice (PCLS) models. The in silico tools
with computational simulations like quantitative structure–activity
relationships (QSAR), pharmacokinetics (PK) and pharmacodynamics (PD),
dose and time response, and quantitative cationic–activity
relationships ((Q)CARs) are used for prediction of the toxicity of
functional materials. In this review, we studied the principle methods
used for degradation studies, different degradation pathways, and
mechanisms of functional material degradation with prototype examples.
We discuss toxicity assessments with different toxicity approaches
used for estimation of the safety and efficacy of functional materials.
