Poly(N-isopropylacrylamide) (PNIPAM) is one of the most well studied thermoresponsive polymers and its microgels undergo a reversible volume phase transition (VPT) at temperatures close to that of the human body. Coupling this property with the unique optical properties of single-walled carbon nanotubes (SWCNT) in the near infrared (NIR) leads to interesting nanohybrids that could be used as multi-responsive sensors/actuators for biological applications.We show the synthesis of thermoresponsive SWCNT/PNIPAM hybrids using two different non-covalent strategies, preserving the nanotube optical properties such as fluorescence. The first strategy involves the dispersion of the SWCNT in water with sodium dodecyl sulfate (SDS), and subsequent in situ synthesis of PNIPAM microgels inside the SDS coatings around the nanotubes. The second strategy starts with modifying the nanotubes with a pyrene derivative, which in turn is used as the starting point for the in situ polymerization of the PNIPAM microgels, thus ensuring that the polymer grows around the nanotubes. In both cases, we obtain hybrids showing a phase transition at temperatures close to that of the human body, with the absorption and fluorescence spectra of the hybrids in the NIR changing in response to the changing dielectric environment. These systems could be used as actuators/sensors in biological systems.

ContextSingle-wall carbon nanotubes (SWCNT) dispersed in water with the help of sodium dodecyl sulfate (SDS) surfactants exhibit a temperature dependent near infrared (NIR) exciton spectrum. Due to their biocompatibility and NIR spectrum falling within the transparent window for biological tissue, SWCNTs hold potential for sensing temperature inside cells. Here, we seek to elucidate the mechanism responsible for this temperature dependence, focusing on changes in the water coverage of the SWCNT as the surfactant structure changes with temperature. We compare optical absorption spectra in the UV–Vis-IR range and fully atomistic molecular dynamics (MD) simulations. The observed temperature dependence of the spectra for various SWCNTs may be attributed to changes in the dielectric environment and its impact on excitons. MD simulations reveal that the adsorbed SDS molecules effectively shield the SWCNT, with ~ 70% of water molecules removed from the first two adlayers; this coverage shows a modest temperature dependence. Although we are not able to directly demonstrate how this influences the NIR spectrum, this represents a potential pathway given the strong influence of the water environment on the excitons in SWCNTs.MethodsOptical absorption measurements were carried out in the UV–Vis-NIR range using a Varian Cary 5000 spectrophotometer in a temperature-controlled environment. PeakFit™ v. 4.06 was used as peak-fitting program in the spectral range 900–1400 nm (890–1380 meV) as a function of the temperature. Fully atomistic molecular dynamics simulations were conducted using the NAMD2 package. The CHARMM force field comprising two-body bond stretching, three-body angle deformation, four-body dihedral angle deformation, and nonbonded interactions (electrostatic and Lennard–Jones 6–16 potentials) was employed.

Recent advancements in materials science have shed light on the potential of exploring hierarchical assemblies of molecules on surfaces, driven by both fundamental and applicative challenges. This field encompasses diverse areas including molecular storage, drug delivery, catalysis, and nanoscale chemical reactions. In this context, the utilization of nanotube templates (NTs) has emerged as promising platforms for achieving advanced one-dimensional (1D) molecular assemblies. NTs offer cylindrical, crystalline structures with high aspect ratios, capable of hosting molecules both externally and internally (Mol@NT). Furthermore, NTs possess a wide array of available diameters, providing tunability for tailored assembly. This review underscores recent breakthroughs in the field of Mol@NT. The first part focuses on the diverse panorama of structural properties in Mol@NT synthesized in the last decade. The advances in understanding encapsulation, adsorption, and ordering mechanisms are detailed. In a second part, the review highlights the physical interactions and photophysics properties of Mol@NT obtained by the confinement of molecules and nanotubes in the van der Waals distance regime. The last part of the review describes potential applicative fields of these 1D heterostructures, providing specific examples in photovoltaics, luminescent materials, and bio-imaging. A conclusion gathers current challenges and perspectives of the field to foster discussion in related communities.

Despite 15 years of extensive investigation, the fabrication and study of nanofluidic devices that incorporate a single carbon nanotube (CNT) still represents a remarkable experimental challenge. In this study, we present the fabrication of nanofluidic devices that integrate an individual single-walled CNT (SWCNT), showcasing a notable reduction in noise by 1 -3 orders of magnitude compared to conventional devices. This achievement was made possible by employing high dielectric constant materials for both the substrate and the CNT-covering layer. Furthermore, we provide a detailed account of the crucial factors contributing to the successful fabrication of SWCNT-based nanofluidic devices that are reliably leak-free, plug-free, and long-lived. Key considerations include the quality of the substrate-layer interface, the nanotube opening, and the effective removal of photoresist residues and trapped microbubbles. We demonstrate that these devices, characterized by a high signal-tonoise ratio, enable spectral noise analysis of ionic transport through an individual SWCNT, thus showing that SWCNTs obey Hooge's law in 1/ f at low frequencies. Beyond advancing our fundamental understanding of ion transport in SWCNTs, these ultralow-noise measurements open avenues for leveraging SWCNTs in nanopore sensing applications for single-molecule detection, offering high sensitivity and identification capabilities.

Summary In this study, a 4% (w/w) dispersion of a commercial patatin‐rich potato protein isolate (Po‐PI) was pressurised at 400 MPa up to 48 h at 20 °C. Protein aggregation induced by high‐pressure processing (HHP) was followed by dynamic light scattering, intrinsic fluorescence ( in‐situ or ex‐situ ) or SAXS analysis. Surface properties (surface hydrophobicity and interfacial properties) of the HHP‐induced aggregates were also investigated. A gradual dimer dissociation/protein unfolding was observed under pressure. Po‐PI exhibited a slow relaxation time under pressure. Long‐time HHP (>4 h) induced significant modification of the Po‐PI protein structure with partial non‐reversible unfolding. After 48 h of pressurisation at 400 MPa, large aggregates (160 nm) were obtained and a monomodal distribution in intensity and in number frequency was observed indicating a controlled aggregation. Up to 24 h of pressurisation at 400 MPa, intermediate states were obtained after high‐pressure release. SDS‐PAGE profiles showed that HHP‐induced aggregation of Po‐PI was driven by non‐covalent interactions. All high‐pressure processed dispersions displayed a higher surface hydrophobicity as compared to non‐treated Po‐PI. Po‐PI dispersion treated for 8 h at 400 MPa presented the lowest adsorption rate, the highest final surface tension and formed the most rigid interfacial film. Po‐PI showed resistance to moderate pressure levels (400 MPa) and long pressure application times were required to induce significant protein denaturation/aggregation (≥24 h) and to optimally modify its interfacial properties (8 h).

Photoredox catalysis is becoming more and more prevalent in the 21st century as a new tool for organic and polymer synthesis. In addition, this domain clearly fits the expectations of the twelve principles of green chemistry. However, access to metal containing photosensitizers is not always straightforward and can require long reaction times, the use of toxic solvents and multi-step synthesis. These are definitely drawbacks that could be overcome with the use of novel technologies. In this report, we develop a one-pot two-step synthesis of iron(II) photosensitizers using ball-milling. Overall reaction times were drastically reduced, no solvent was needed during the reaction, and ten complexes could be isolated in high yields (73–99%). Using a transparent milling jar, the formation of the complexes could be followed using in situ Raman spectroscopy.