The global pollution caused by plastics and microplastics is stimulating intense research towards more environmentally friendly materials, preserving the remarkable application characteristics of the currently available polymers. Among these, polyhydroxyalkanoates (PHAs) have been hailed as the solution to replace conventional, oil-based plastics. Given their biodegradable nature and mechanical properties, their use can be envisioned in a wide range of applications reducing the environmental footprint. Several types of processes have been proposed for their production, which can be grouped in three main classes: (i) microbiological, (ii) enzymatic and (iii) chemical processes. Given the significant amount of literature available on this topic, this review aims to critically analyse what has been proposed so far in each of these classes, with specific reference to their potential to provide bioplastics that can actually replace the currently available materials. A comparison is made, based on the following aspects: achievable molecular structures (such as molecular weight and composition distributions), raw-material and production costs and availability of large-scale production technologies. Finally, some considerations and ideas on what should be further investigated and implemented to realize the economically sustainable production of PHA are brought forward. the melting temperature from 40 to 180°C, according to their chemical composition and chain length. However, depending on the type of PHA, composition and molecular weight, these properties vary greatly, even

Oligonucleotides (ONs) are gaining increasing importance as a promising novel class of biopharmaceuticals. Thanks to their fundamental role in gene regulation, they can be used to develop custom-made drugs (also called N-to-1) able to act on the gene expression at pretranslational level. With recent approvals of ON-based therapeutics by FDA, a growing demand for high-quality chemically-modified ONs is emerging and their market is expected to impressively prosper in the very next future. To satisfy this growing market demand, a scalable and economically sustainable ON production is needed. In this paper, the state of the art of the whole ON production process is illustrated with the aim of highlighting the most promising routes towards the auspicated market-size production. In particular, the most recent advancements in both the upstream stage, mainly based on solid-phase synthesis and recombinant technology, and the downstream one, focusing on chromatographic techniques, are reviewed. Since ON production is projected to expand to the large scale, automatized multi-column technologies will reasonably be required soon to replace the current ones based on batch single-column operations. Cutting edge purification solutions, based on continuous chromatography, will be thus presented in the last part of this review.

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