Self-assembly on optical fibers: a powerful nanofabrication tool for next generation “lab-on-fiber” optrodes

Abstract

A comprehensive review of the self-assembly techniques applied to the development of nanostructured sensing devices based on optical fibers.

Cooperative Self-Assembly of Pyridine-2,6-Diimine-Linked Macrocycles into Mechanically Robust Nanotubes

“…[15] NT-NF,derived from MC 1 with 1equiv of CF 3 CO 2 H, demonstrated ahigher Youngsmodulus (1.33 AE 0.35 GPa) than touch-spun fibers of PEO (0.18 AE 0.05 GPa), polycaprolactone (PCL) (0.02 AE 0.00 GPa), and ap oly(ester urea) (PEU) [21] (0.68 AE 0.04 GPa) ( Figure 4G,T ables S11-S13). [24][25][26][27][28] This work establishes that imine-linked macrocycles, which are readily designed and prepared, assemble into high-aspect ratio nanotubes under mild conditions when they contain easily protonatable groups.T he enhanced basicity of the pyridine moiety compared to the imine linkages in the first inverse chromonic liquid crystal macrocycles enables assembly to proceed through the formation of pyridinium ions,i nstead of hydrolytically unstable iminium ions.T he assembly of MC 1 under sub-stoichiometric acid loadings is highly cooperative,a sd emonstrated by GPC measurements of macrocycle disappearance as well as fluorescence spec-troscopy.T he assembled nanotubes were processed into NT-NF via touch-spinning.T he resulting fibers demonstrated aY oungsm odulus of 1.33 GPa, exceeding that of several covalently linked polymers and biological filaments.M acrocycles that relied on protonating the imines with excess CF 3 CO 2 Hd id not form nanofibers suitable for mechanical testing.These findings demonstrate ageneral design principle for the synthesis of macrocycle assembles under mild conditions,a swell as the ability to touch-spin nanofibers of robust supramolecular assemblies. [23] Theh igh modulus of the NT-NF is presumably due to the interplay of multiple intermolecular forces,s uch as the electrostatic interactions that govern the initial assembly event, the hydrophobic interactions of the decyloxy side chains that are forced into close proximity,aswell as the p-p interactions present from macrocycle self-assembly.…”

Lab-On-Fiber Technology: A Roadmap toward Multifunctional Plug and Play Platforms

“…To finally translate LOF platforms from lab curiosities into plug and play devices and components ready to be used in strategic industrial scenarios, sustainable and cost-effective mass production technologies are of fundamental importance. A valid solution could be provided by the latest advances in self-assembly routes and their extension to optical fiber substrates, as recently reviewed in [ 24 ].…”

“…The self-assembly process relies on the “autonomous organization of materials and structures” [ 24 ] and thus is inherently economical and suitable for simultaneous and appropriate operations with multiple fibers. Therefore, this approach provides a potential solution for high-throughput fabrication processes.…”

“…Although nanotechnology and nanophotonics constitute the most suitable “key enabling technologies” to realistically meet the above goals, considerable research effort is needed to address important issues and overcome relevant technological barriers and limitations to translate LOF visions into reality [ 24 , 25 , 26 , 27 ]. Notably, material integration onto unconventional substrates with full spatial control at the nanoscale is needed, and light–matter interaction mechanisms must be identified.…”

Cooperative Self‐Assembly of Pyridine‐2,6‐Diimine‐Linked Macrocycles into Mechanically Robust Nanotubes

“…In addition to its higher Young's modulus than touch‐spun nanofibers of covalent polymers, the NT‐NFs demonstrate a Young's modulus higher than biological materials of interest, such as: actin (1.30 GPa), collagen type I (0.10–0.36 GPa), and tubulin dimers (0.6 GPa) . The high modulus of the NT‐NF is presumably due to the interplay of multiple intermolecular forces, such as the electrostatic interactions that govern the initial assembly event, the hydrophobic interactions of the decyloxy side chains that are forced into close proximity, as well as the π‐π interactions present from macrocycle self‐assembly …”