Wan Sharuzi Wan Harun

Nose-to-brain (N2B) delivery is a practical, non-invasive strategy for CNS targeting that can increase brain exposure while limiting systemic exposure. This review integrates three milestones in N2B delivery, formulations, devices, and quantitative evaluation strategies, to define design rules for effective olfactory/trigeminal deposition and enhance translational relevance. Formulations emphasize mucoadhesive systems, nanoparticle carriers (polymeric, lipid-based, and hybrid), nano-emulsions, and stimuli-responsive “smart” gels that prolong nasal residence. Regarding device advancements, the review covers conventional nasal sprays optimized for plume geometry and droplet size. Furthermore, it examines breath-actuated metered sprays, which promote soft palate closure to route aerosols to superior regions, and vibrating mesh nebulizers capable of low-velocity mists for improved upper cavity deposition. Quantitative evaluation is discussed, including 3D-printed, anatomy-accurate nasal casts, high-speed spray diagnostics, and computational fluid dynamics (CFD). This review further links formulation and device parameters to regional deposition. Available clinical and animal data illustrate the feasibility of these approaches, safety considerations, and user-technique dependencies, while highlighting the need for standardized, anatomy-aware testing protocols. Together, these developments suggest that co-designed formulation device platforms, validated by cast/CFD metrics and supported by clinical imaging or pharmacokinetic data, can support N2B product development toward consistent, patient-relevant outcomes.

The topic of this review is timely and highly relevant. The article's primary strength is its function as a comprehensive data repository, gathering a wide range of recent data on various thermoplastic nanocomposites into one location. This makes it...

Fused Deposition Modelling (FDM) of Wood-Plastic Composites (WPCs) offers a compelling pathway towards sustainable manufacturing. However, the progression from prototyping to functional components is governed by a fundamental conflict: the pursuit of high wood content for sustainability directly opposes the thermo-rheological constraints of the extrusion process. This review critically analyses this conflict, arguing it is the primary source of the two main defects that limit structural applications: severe mechanical anisotropy from weak interlayer adhesion, and multi-scale porosity inherent to both the feedstock and the printing process. By deconstructing the material systems and process-structure-property relationships, this review synthesises current strategies to mitigate these challenges. Ultimately, this review argues that the future of the field depends on a paradigm shift towards intelligent manufacturing, integrating predictive modelling with novel bio-based materials and leveraging the unique properties of WPCs for functionally graded components and environmentally responsive 4D printing.

Additive Manufacturing (AM) of polymer composites has matured from a prototyping tool into a viable process for functional components. This review critically assesses this progress, focusing on the intersection of performance, sustainability, and industrial readiness. Advancements in AM processes now accommodate diverse reinforcements, from nanoscale fillers to continuous fibres, yielding parts with exceptional mechanical properties. Concurrently, a sustainability strategy has emerged, prioritising bio-based and recycled feedstocks, enhanced process energy efficiency through novel out-of-oven curing, and circular economy principles. However, widespread industrial adoption is hindered by persistent challenges. These include managing fibre-matrix interfacial integrity, the inherent anisotropy of printed parts, complex qualification pathways, and the end-of-life conundrum for composite waste. To overcome these barriers, future research must pivot to integrated, data-driven approaches. Leveraging computational optimisation and artificial intelligence is essential to navigate the trade-offs between performance, cost, and lifecycle sustainability, and ultimately resolve the certification paradox to unlock the full potential of this transformative technology.