While the optical and spectroscopic properties of gold nanoparticles are widely used for chemical, bioanalytical,
and biomedical applications, the study of the size correlation with these properties for nanoparticles in solutions
is rather limited. This paper describes the results of a systematic study of such a correlation for gold
nanoparticles with diameters ranging from 10 to 100 nm in aqueous solutions. The high monodispersity of
these nanoparticles permitted a meaningful correlation of the particle size with the surface plasmon (SP)
resonance band properties and the surface-enhanced Raman scattering (SERS) spectroscopic properties. This
correlation is compared to the results from the simulation based on Mie theory. The close agreement between
the experimental and the theoretical results provides insight into the validity of determining the wavelength
of the SP resonance band as a measure of the particle size. The size correlation with the SERS intensity from
the adsorption of 4-mercaptobenzoic acid on the nanoparticles in aqueous solutions reveals the existence of
a critical size of the nanoparticles in the solution beyond which the particle−particle interaction is operative
and responsible for the SERS effect. These findings serve as the basis of size correlations for exploiting the
optical and spectroscopic properties of gold nanoparticles of different sizes in aqueous solutions in analytical
or bioanalytical applications.
Background: Quercetin, a well-known naturally occurring polyphenol, has recently been shown by molecular docking, in vitro and in vivo studies to be a possible anti-COVID-19 candidate. Quercetin has strong antioxidant, anti-inflammatory, immunomodulatory, and antiviral properties, and it is characterized by a very high safety profile, exerted in animals and in humans. Like most other polyphenols, quercetin shows a very low rate of oral absorption and its clinical use is considered by most of modest utility. Quercetin in a delivery-food grade system with sunflower phospholipids (Quercetin Phytosome ® , QP) increases its oral absorption up to 20-fold. Methods: In the present prospective, randomized, controlled, and open-label study, a daily dose of 1000 mg of QP was investigated for 30 days in 152 COVID-19 outpatients to disclose its adjuvant effect in treating the early symptoms and in preventing the severe outcomes of the disease.
Results:The results revealed a reduction in frequency and length of hospitalization, in need of non-invasive oxygen therapy, in progression to intensive care units and in number of deaths. The results also confirmed the very high safety profile of quercetin and suggested possible anti-fatigue and pro-appetite properties. Conclusion: QP is a safe agent and in combination with standard care, when used in early stage of viral infection, could aid in improving the early symptoms and help in preventing the severity of COVID-19 disease. It is suggested that a double-blind, placebo-controlled study should be urgently carried out to confirm the results of our study.
An effective protocol has been developed that allows the smooth protodecarboxylation of diversely functionalized aromatic carboxylic acids within 5-15 min. In the presence of at most 5 mol % of an inexpensive catalyst generated in situ from copper(I) oxide and 1,10-phenanthroline, even nonactivated benzoates were converted in high yields and with great preparative ease.
The dimeric Pd(I)-complex [Pd(μ-Br)(P(t)Bu3)]2 was found to be highly active for catalyzing double-bond migration in various substrates such as unsaturated ethers, alcohols, amides, and arenes, under mild conditions. It efficiently mediates the conversion of allylic esters into enol esters, rather than inserting into the allylic C-O bond. The broad applicability of this reaction was demonstrated with the synthesis of 22 functionalized enol esters.
Introducing CF3: Arylboronic acid pinacol esters are converted into the corresponding benzotrifluorides with the easy‐to‐use one‐component trifluoromethylating reagent potassium (trifluoromethyl)trimethoxyborate, mediated by copper acetate under an oxygen atmosphere (see scheme).
Excessive use of
synthetic nondegradable polymers has led to the
proliferation of microplastics in the oceans as well as polluted landscapes.
Herein, we report a new sustainable approach for the development of
oil- and water-resistant paper. Chitosan–graft–poly(dimethylsiloxane) (CHI–g–PDMS)
copolymers were prepared by the reaction of poly(dimethylsiloxane)
(PDMS) with chitosan. The CHI–g–PDMS
graft copolymer was characterized by 1H nuclear magnetic
resonance (NMR) analysis. Zein, a coproduct of the bioethanol industry,
was blended with CHI–g–PDMS in a water/ethanol
solution and subsequently applied as a coating on an unbleached Kraft
paper. The coated paper substrates were evaluated for their oil resistance
via kit rating and oil contact angle measurements, while the water
resistance was determined via Cobb60 value and water contact angle
measurements. In addition, the pulp was successfully recovered from
the coated paper. Scanning electron microscopy (SEM) analysis was
used to investigate the variation in the texture of the paper before
and after the coating treatment. Thanks to the efficient pulp recovery
and the biodegradable nature of the coating ingredients (chitosan
and zein), this novel water- and oil-resistant paper will positively
impact the environment by offering potential replacements for single-use
plastic applications, and will thus help to minimize ocean microplastics
and the burdens placed on landfills.
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