Photoreductive generation of amorphous bismuth nanoparticles using polysaccharides--bismuth-cellulose nanocomposites

A novel delayed lateral flow immunoassay for enhanced detection of SARS-CoV-2 spike antigen

A new detection strategy was developed to improve the sensitivity of a lateral flow immunoassay platform utilizing a delayed hydrophobic barrier fabricated with trimethylsilyl cellulose (TMSC). The SARS-CoV-2 spike receptor-binding domain (SARS-CoV-2 SP RBD) antigen was chosen as a model analyte to demonstrate the superior detectability of this scheme. The novel device consists of 2 separate layers, so-called delayed lateral flow immunoassay (d-LFIA). The upper layer is intended for the analyte or sample flow path, where the test solution flows freely straight to the detection zone to bind with the primary antibody. The lower layer, located just underneath, is designed for the SARS-CoV-2 spike receptor-binding domain-conjugated gold nanoparticles (SARS-CoV-2 SP RBD-AuNPs) used for producing a colorimetric signal. This layer is fabricated with a TMSC barrier to time-delay the movement of SARS-CoV-2 SP RBD-AuNPs, thus allowing the antigen to bind with the primary antibody more efficiently. This platform exhibited a 2.6-fold enhancement in the sensitivity and 9.1-fold improvement in the limit of detection (LOD) as compared with the conventional LFIA. In addition, this d-LFIA device was satisfactorily applied to accurate screening of COVID-19 patients.

Comparison of Trimethylsilyl Cellulose-Stabilized Carbonate and Hydroxide Nanoparticles for Deacidification and Strengthening of Cellulose-Based Cultural Heritage

Herein, colloidal dispersions of alkaline nanoparticles (NPs: CaCO₃ and Mg(OH)₂) are stabilized by trimethylsilyl cellulose (TMSC) in hexamethyldisiloxane and employed to treat historical wood pulp paper by an effortless dip-coating technique. Both alkaline NPs exhibit high stability and no size and shape changes upon stabilization with the polymer, as shown by UV-vis spectroscopy and transmission electron microscopy. The long-term effect of NP/TMSC coatings is investigated in detail using accelerated aging. The results from the pH-test and back-titration of coated papers show a complete acid neutralization (pH ∼ 7.4) and introduction of adequate alkaline reserve even after prolonged accelerated aging. Scanning electron microscopy-energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and infrared and water contact angle measurements showed the introduction of a thin and smooth hydrophobic NP/TMSC coating on the paper fibers. Acid-catalyzed desilylation of TMSC was observed by declining C-Si infrared absorbance peaks upon aging. The CaCO₃ coatings are superior to Mg(OH)₂ with respect to a reduced yellowing and lower cellulose degradation upon aging as shown by colorimetric measurements and degree of polymerization analysis. The tensile strength and folding endurance of coated and aged papers are improved to 200-300 and 50-70% as illustrated by tensile strength and double folding endurance measurements.

Ultrathin Films of Cellulose: A Materials Perspective

A literature review on ultrathin films of cellulose is presented. The review focuses on different deposition methods of the films-all the way from simple monocomponent films to more elaborate multicomponent structures-and the use of the film structures in the vast realm of materials science. The common approach of utilizing cellulose thin films as experimental models is therefore omitted. The reader will find that modern usage of cellulose thin films constitutes an exciting emerging area within materials science and it goes far beyond the traditional usage of the films as model systems.

Green Procedure to Manufacture Nanoparticle-Decorated Paper Substrates

For this study, a paper impregnated with silver nanoparticles (AgNPs) was prepared. To prepare the substrates, aqueous suspensions of pulp fines, a side product from the paper production, were mixed with AgNP suspensions. The nanoparticle (NP) synthesis was then carried out via laser ablation of pure Ag in water. After the sheet formation process, the leaching of the AgNPs was determined to be low while the sheets exhibited antimicrobial activity toward Escherichia coli (E. coli).

On the formation of Bi2S3-cellulose nanocomposite films from bismuth xanthates and trimethylsilyl-cellulose

The synthesis and characterization of bismuth sulfide-cellulose nanocomposite thin films was explored. The films were prepared using organosoluble precursors, namely bismuth xanthates for Bi₂S₃ and trimethylsilyl cellulose (TMSC) for cellulose. Solutions of these precursors were spin coated onto solid substrates yielding homogeneous precursor films. Afterwards, a heating step under inert atmosphere led to the formation of thin nanocomposite films of bismuth sulfide nanoparticles within the TMSC matrix. In a second step, the silyl groups were cleaved off by vapors of HCl yielding bismuth sulfide/cellulose nanocomposite films. The thin films were characterized by a wide range of surface sensitive techniques such as atomic force microscopy, attenuated total reflection infrared spectroscopy, transmission electron microscopy and wettability investigations. In addition, the formation of the nanoparticle directly in the TMSC matrix was investigated in situ by GI-SWAXS using a temperature controlled sample stage.

Polysaccharide stabilized nanoparticles for deacidification and strengthening of paper

This paper reports an investigation on the use of a highly stable colloidal organic dispersion consisting of a polysaccharides and alkaline nanoparticles for the simultaneous deacidification and strengthening of historical wood pulp papers.