Micro and Nanoplastics Identification: Classic Methods and Innovative Detection Techniques

Micro and nanoplastics are fragments with dimensions less than a millimeter invading all terrestrial and marine environments. They have become a major global environmental issue in recent decades and, indeed, recent scientific studies have highlighted the presence of these fragments all over the world even in environments that were thought to be unspoiled. Analysis of micro/nanoplastics in isolated samples from abiotic and biotic environmental matrices has become increasingly common. Hence, the need to find valid techniques to identify these micro and nano-sized particles. In this review, we discuss the current and potential identification methods used in microplastic analyses along with their advantages and limitations. We discuss the most suitable techniques currently available, from physical to chemical ones, as well as the challenges to enhance the existing methods and develop new ones. Microscopical techniques (i.e., dissect, polarized, fluorescence, scanning electron, and atomic force microscopy) are one of the most used identification methods for micro/nanoplastics, but they have the limitation to produce incomplete results in analyses of small particles. At present, the combination with chemical analysis (i.e., spectroscopy) overcome this limit together with recently introduced alternative approaches. For example, holographic imaging in microscope configuration images microplastics directly in unfiltered water, thus discriminating microplastics from diatoms and differentiates different sizes, shapes, and plastic types. The development of new analytical instruments coupled with each other or with conventional and innovative microscopy could solve the current problems in the identification of micro/nanoplastics.

nm-Resolution Functional Pattern Transfer to an Amorphous Elastomeric Material

Here, we show that striped monolayers of diyne amphiphiles, assembled on graphite and photopolymerized, can be covalently transferred to polydimethylsiloxane (PDMS), an elastomer common in applications including microfluidics, soft robotics, wearable electronics, and cell culture. This process creates precision polymer films < 1 nm thick, with 1-nm-wide functional patterns, that control interfacial wetting, reactivity, and adsorption of flexible, ultranarrow inorganic nanowires. The polydiacetylenes exhibit polarized fluorescence emission, revealing polymer location, orientation, and environment, and resist engulfment, a common problem in PDMS functionalization. These findings illustrate a route for controlling surface chemistry well below the length scale of heterogeneity in an amorphous material.

nm-Resolution Functional Pattern Transfer to an Amorphous Elastomeric Material

Here, we show that striped monolayers of diyne amphiphiles, assembled on graphite and photopolymerized, can be covalently transferred to polydimethylsiloxane (PDMS), an elastomer common in applications including microfluidics, soft robotics, wearable electronics, and cell culture. This process creates precision polymer films < 1 nm thick, with 1-nm-wide functional patterns, that control interfacial wetting, reactivity, and adsorption of flexible, ultranarrow inorganic nanowires. The polydiacetylenes exhibit polarized fluorescence emission, revealing polymer location, orientation, and environment, and resist engulfment, a common problem in PDMS functionalization. These findings illustrate a route for controlling surface chemistry well below the length scale of heterogeneity in an amorphous material.