Nano-FTIR spectroscopy is a technique where atomic force microscopy (AFM) and infrared (IR) spectroscopy are combined to obtain chemical information with a lateral resolution of some tens of nm. It has been used to study numerous solid surfaces and recently also liquids including water have been examined by separating the liquid from the AFM tip by a thin lid. However, although the water stretching vibrations are significantly more intense than the bending vibration in conventional IR spectroscopy, only the bending vibration has been observed in nano-FTIR spectroscopy so far. In this article we show that also the stretching vibrations of liquid H2O, D2O, HOD, and aqueous salt solutions can be probed in nano-FTIR spectroscopy. Nano-FTIR absorption and phase spectra have been acquired at different harmonics and it was found the third optical harmonic (O3) in the nano-FTIR absorption spectra exhibited the highest resemblance with attenuated total reflection (ATR). Being able to probe water stretching vibrations with nano-FTIR spectroscopy is of importance since the stretching vibrations contain considerably more detailed information regarding for example hydrogen bonding strength than the bending vibration. In addition, it enables studies of the essential interactions between water and biomolecules. Furthermore, this work highlights both advantages and challenges that nano-FTIR spectroscopy in a liquid sample cell has and importance of further studies that lead to a better understanding of the near-field signals in liquids.

Inhalation therapy treating severe infectious disease is among the more complex and emerging topics in controlled drug release. Micron-sized carriers are needed to deposit drugs into the lower airways, while nano-sized carriers are of preference for cell targeting. Here, we present a novel and versatile strategy using micron-sized spherical particles with an excellent aerodynamic profile that dissolve in the lung fluid to ultimately generate nanoparticles enabling to enhance both extra- and intra-cellular drug delivery (i.e., dual micro-nano inhalation strategy). The spherical particles are synthesised through the condensation of nano-sized amorphous silicon dioxide resulting in high surface area, disordered mesoporous silica particles (MSPs) with monodispersed size of 2.43 μm. Clofazimine (CLZ), a drug shown to be effective against multidrug-resistant tuberculosis, was encapsulated in the MSPs obtaining a dry powder formulation with high respirable fraction (F.P.F. <5 μm of 50%) without the need of additional excipients. DSC, XRPD, and Nitrogen adsorption-desorption indicate that the drug was fully amorphous when confined in the nano-sized pores (9–10 nm) of the MSPs (shelf-life of 20 months at 4 °C). Once deposited in the lung, the CLZ-MSPs exhibited a dual action. Firstly, the nanoconfinement within the MSPs enabled a drastic dissolution enhancement of CLZ in simulated lung fluid (i.e., 16-fold higher than the free drug), increasing mycobacterial killing than CLZ alone (p = 0.0262) and reaching concentrations above the minimum bactericidal concentration (MBC) against biofilms of M. tuberculosis (i.e., targeting extracellular bacteria). The released CLZ permeated but was highly retained in a Calu-3 respiratory epithelium model, suggesting a high local drug concentration within the lung tissue minimizing risk for systemic side effects. Secondly, the micron-sized drug carriers spontaneously dissolve in simulated lung fluid into nano-sized drug carriers (shown by Nano-FTIR), delivering high CLZ cargo inside macrophages and drastically decreasing the mycobacterial burden inside macrophages (i.e., targeting intracellular bacteria). Safety studies showed neither measurable toxicity on macrophages nor Calu-3 cells, nor impaired epithelial integrity. The dissolved MSPs also did not show haemolytic effect on human erythrocytes. In a nutshell, this study presents a low-cost, stable and non-invasive dried powder formulation based on a dual micro-nano carrier to efficiently deliver drug to the lungs overcoming technological and practical challenges for global healthcare.

Local heterogeneities can have significant effects on the performance of anti-corrosion coatings. Even small features can act as initiation points for damage and result in corrosion of the substrate material. Analysis methods with high spatial resolution and the ability to collect information relevant to crosslinking and degradation behavior of these coatings are therefore highly relevant. In this work, we demonstrate the utility of nanomechanical AFM measurements and nano-FTIR in investigating the nanoscale mechanical and chemical properties of two polyester coil coating clearcoats before and after weathering. On the nanoscale, weathering led to a stiffer and less deformable coating with less variation in the nanomechanical properties. Chemical degradation was quantified using changes in band ratios in the IR-spectra. Macro and nano-scale measurements showed similar trends with the latter measurements showing larger heterogeneity. Our results demonstrate the usefulness of the described analysis techniques and will pave the way for future studies of local properties in other coating systems and formulations.

Nanoscale infrared (IR) spectroscopy and microscopy, enabling the acquisition of IR spectra and images with a lateral resolution of 20 nm, is employed to chemically characterize individual cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) to elucidate if the CNCs and CNFs consist of alternating crystalline and amorphous domains along the CNF/CNC. The high lateral resolution enables studies of the nanoscale morphology at different domains of the CNFs/CNCs: flat segments, kinks, twisted areas, and end points. The types of nano-cellulose investigated are CNFs from tunicate, CNCs from cotton, and anionic and cationic wood-derived CNFs. All nano-FTIR spectra acquired from the different samples and different domains of the individual nanocellulose particles resemble a spectrum of crystalline cellulose, suggesting that the non-crystalline cellulose signal observed in macroscopic measurements of nanocellulose most likely originate from cellulose chains present at the surface of the nanocellulose particles.

From a circular economyperspective, one-pot strategies for theisolation of cellulose nanomaterials at a high yield and with multifunctionalproperties are attractive. Here, the effects of lignin content (bleachedvs unbleached softwood kraft pulp) and sulfuric acid concentrationon the properties of crystalline lignocellulose isolates and theirfilms are explored. Hydrolysis at 58 wt % sulfuric acid resulted inboth cellulose nanocrystals (CNCs) and microcrystalline celluloseat a relatively high yield (>55%), whereas hydrolysis at 64 wt% gaveCNCs at a lower yield (<20%). CNCs from 58 wt % hydrolysis weremore polydisperse and had a higher average aspect ratio (1.5-2x),a lower surface charge (2x), and a higher shear viscosity (100-1000x).Hydrolysis of unbleached pulp additionally yielded spherical nanoparticles(NPs) that were <50 nm in diameter and identified as lignin bynanoscale Fourier transform infrared spectroscopy and IR imaging.Chiral nematic self-organization was observed in films from CNCs isolatedat 64 wt % but not from the more heterogeneous CNC qualities producedat 58 wt %. All films degraded to some extent under simulated sunlighttrials, but these effects were less pronounced in lignin-NP-containingfilms, suggesting a protective feature, but the hemicellulose contentand CNC crystallinity may be implicated as well. Finally, heterogeneousCNC compositions obtained at a high yield and with improved resourceefficiency are suggested for specific nanocellulose uses, for instance,as thickeners or reinforcing fillers, representing a step toward thedevelopment of application-tailored CNC grades.

Hypothesis: Solid-state polymer adsorption offers a distinct approach for surface modification. These ultrathin, so-called Guiselin layers can easily be obtained by placing a polymer melt in contact with an interface, followed by a removal of the non-adsorbed layer with a good solvent. While the mechanism of formation has been well established for Guiselin layers, their stability, crucial from the perspective of materials applications, is not. The stability is a trade-off in the entropic penalty between cooperative detachment of the number of segments directly adsorbed on the substrate and consecutively pinned monomers. Experiments: Experimental model systems of Guiselin layers of polystyrene (PS) on silicon wafers with native oxide layer on top were employed. The stability of the adsorbed layers was studied as a function of PS molecular weight and polydispersibility by various microscopic and spectroscopic tools as well as quasi-static contact angle measurements. Findings: Adsorbed layers from low molecular weight PS were disrupted with typical spinodal decomposition patterns whereas high molecular weight (>500 kDa) PS resulted in stable, continuous layers. Moreover, we show that Guiselin layers offer an enticing way to modify a surface, as demonstrated by adsorbed PS that imparts a hydrophobic character to initially hydrophilic silicon wafers.

Certain ionic liquids (ILs), such as 1-butyl-3-methylimidazolium chloride (bmimCl) and 1-ethyl-3-methylimidazolium acetate (emimAc), are potent cellulose solvents, but the high viscosity of the resulting solutions is problematic in many applications. Organic co-solvents are often employed to alleviate this problem; however, our understanding of the intermolecular interactions determining the IL/co-solvent mixture performance is very limited, hampering the further development of this class of cellulose solvents. Herein, we applied infrared spectroscopy (IR), Raman spectroscopy, and quantum chemical model calculations to investigate the intermolecular interactions in differently concentrated mixtures of bmimCl and emimAc with amidic co-solvents, N-methyl-2-pyrrolidone (NMP) and N-vinyl-2-pyrrolidone (NW). Based on the detailed analysis of the vibrational spectra of individual mixture components and the improved assignment of the relevant characteristic bands, we determined that brnim(+) -co-solvent and emim(+) -co-solvent associates, stabilized by the hydrogen bonds between amidic carbonyl oxygens and the CH groups of the imidazolium rings, are formed in the mixtures. In addition, the data pointed to concomitant disruption of the H-bonds between the IL counterions as the co-solvent concentration was increased, which may indicate partial dissociation of the IL ion pairs. Further, through an extensive deconvolution analysis, we quantified the molar fractions of the co-solvent molecules involved in the associate formation, finding that this fraction is significantly lower for emimAc than for bmimCl mixtures at all the studied concentrations. On the other hand, the influence of the amidic co-solvent structure was negligible, suggesting that also other (aprotic) amides may be applicable as co-solvents. Furthermore, the calculated molar ratio of IL to interacting co-solvent molecules highlighted the possible differences in the associate stoichiometry. The findings indicate that the lower affinity of the IL to co-solvents in emimAc-based mixtures may lead to the retaining of larger IL-rich clusters and, consequently, the comparatively better performance of the system in cellulose dissolution. Finally, increased temperature was found to influence all the studied systems similarly, inflicting about 20% decrease in the fraction of interacting co-solvent molecules at 85 degrees C as compared to room temperature. In summary, the results of this study provide important implications for the design of new solvent systems for cellulose dissolution.