Carbon quantum dots (CQDs) were characterized and their synthesis optimized extensively over recent years. It is becoming more and more important to develop synthesis solutions for CQDs applications ...to allow simple and cheap applications with composite materials. Here, we present a one-pot CQDs reaction in an aqueous polyvinyl alcohol (PVA) solution and the synthesis of transparent UV protection films. The synthesis solution was tuned in a way that transparent UV-protection films cast from unpurified CQDs-PVA solutions could be obtained without the need of yield consuming purification steps. Measuring the impact of varying PVA, branched polyethylene imine (b-PEI), and citric acid (CA) concentrations on the solution's and film's UV/Vis transmission and absorbance allowed elucidating important factors influencing the solution to film property transition. Applying CQDs-PVA films on commercially available PET bottle films resulted in high transparency of the composite film in the visible range (>80%) and UV absorption of over 90%. Lastly, our CQDs-PVA film performed stable UV-blocking and did not show any bleaching effects over several days of UV-exposure.
A simple synthesis of fluorescent carbon quantum dots from lemon juice is described to introduce advanced high-school students and undergraduate college students to nanoparticle synthesis and quantum ...dots. The synthesis is based on the carbonization of lemon juice using only a hot plate stirrer. Column chromatography is used to separate different carbon quantum dots according to their size. This laboratory experiment can be carried out within a 2 h laboratory course and introduces the students to (1) nanotechnology and nanoparticle synthesis, using safe and commonly available chemicals. Furthermore, (2) the concept of fluorescence can be visualized in an intriguing manner using a pocket UV lamp. (3) This experiment serves as an introduction into size-exclusion chromatography. (4) An insight into possible sensing applications is given by the specific fluorescence quenching with an iron(III) solution. The experiment has been tested with 80 students in 4 Swiss high schools, and the knowledge of the students was tested before and after the experiment with a questionnaire. The performance increased by 0.42 ± 0.39 on a grading scale of 1 to 6. The calculated average effect size was 0.76, which is in the range of a medium- to large-effect size, indicating a favorable effect of the experiment on the nanoparticle knowledge of the students.
Herein, we present a water dispersable, magnetic nanoparticle supported "click and release" system. The cleavable linker has been synthesized by using a strain-promoted copper-free "click" reagent to ...establish the specific link and a fluoride cleavable silane moiety for mild cleavage. Small organic molecules, azide-bearing dyes and functionalized enzymes have been bound to the magnetic particle and released in a bioorthogonal way.
Autism is a severe developmental disorder, whose pathogenetic underpinnings are still largely unknown. Temporocortical gray matter from six matched patient-control pairs was used to perform ...post-mortem biochemical and genetic studies of the mitochondrial aspartate/glutamate carrier (AGC), which participates in the aspartate/malate reduced nicotinamide adenine dinucleotide shuttle and is physiologically activated by calcium (Ca(2+)). AGC transport rates were significantly higher in tissue homogenates from all six patients, including those with no history of seizures and with normal electroencephalograms prior to death. This increase was consistently blunted by the Ca(2+) chelator ethylene glycol tetraacetic acid; neocortical Ca(2+) levels were significantly higher in all six patients; no difference in AGC transport rates was found in isolated mitochondria from patients and controls following removal of the Ca(2+)-containing postmitochondrial supernatant. Expression of AGC1, the predominant AGC isoform in brain, and cytochrome c oxidase activity were both increased in autistic patients, indicating an activation of mitochondrial metabolism. Furthermore, oxidized mitochondrial proteins were markedly increased in four of the six patients. Variants of the AGC1-encoding SLC25A12 gene were neither correlated with AGC activation nor associated with autism-spectrum disorders in 309 simplex and 17 multiplex families, whereas some unaffected siblings may carry a protective gene variant. Therefore, excessive Ca(2+) levels are responsible for boosting AGC activity, mitochondrial metabolism and, to a more variable degree, oxidative stress in autistic brains. AGC and altered Ca(2+) homeostasis play a key interactive role in the cascade of signaling events leading to autism: their modulation could provide new preventive and therapeutic strategies.
Tris(2‐carboxyethyl)phosphine (TCEP) is an often‐used reducing agent in biochemistry owing to its selectivity towards disulfide bonds. As TCEP causes undesired consecutive side reactions in various ...analytical methods (e.g., gel electrophoresis, protein labeling), it is usually removed by means of dialysis or gel filtration. Here, an alternative method of separation is presented, namely the immobilization of TCEP on magnetic nanoparticles. This magnetic reagent provides a simple and rapid approach to remove the reducing agent after successful reduction. A reduction capacity of 70 μmol per gram of particles was achieved by using surface‐initiated atom transfer polymerization.
Tris(2‐carboxyethyl)phosphine (TCEP) is an often‐used reducing agent in biochemistry owing to its selectivity towards disulfide bonds. Because TCEP causes undesired consecutive side reactions in various analytical methods (e.g., gel electrophoresis, protein labeling), it is usually removed by means of dialysis or gel filtration. Here, an alternative method of separation is presented, namely the immobilization of TCEP on magnetic nanoparticles.
The use of a p‐nitrobenzyloxycarbonyl (pNZ) protecting group on the FDA‐approved lung cancer drug gemcitabine affords a caged drug with very low in vitro toxicity in a human model cell line (A549). ...To activate this type of caged potent drug, simultaneous presence of two items is needed: platinum nanoparticles and hydrogen‐containing gas mixtures. This combination may later allow a more precise and controlled local delivery of highly potent cytostatic compounds, and may eventually permit reduction of the severe side effects of such chemotherapy treatments. Hydrogen, though an unusual medical agent, is well tolerated, and here used mixtures are derived from diving (deep diving gas). Pt nanoparticles at here used concentrations may eventually be locally deposited into the lungs through minimal invasive inhalation. We demonstrate the use of hydrogen as an on/off uncaging switch and show repeated use of the Pt nanoparticles for a series of uncaging events.
Selective dealloying of metal nanoparticles results in rattle-type hollow carbon nanoshells enclosing platinum nanoparticles, which are able to perform size-selective catalysis. Selective ...functionalization of the outer graphene-like carbon surface prevents agglomeration and leads to well dispersible nanocatalysts in aqueous solutions. The synthesis starts with the production of nanoparticles with a cobalt-platinum-alloy core surrounded by graphene-like carbon
reducing flame spray synthesis. After surface functionalization, simultaneous pore formation in the shell-wall and dissolution of the cobalt results in platinum encapsulated in hollow carbon nanospheres. Catalytic oxidation of differently sized sugars (glucose and maltoheptaose) reveales size-selective catalytic properties of these platinum nanorattles.
Herein, we present the first successful silica coating of poly(lactic acid) (PLA) nanoparticles, resulting in fully coated PLA–silica core–shell nanoparticles. Subsequent dissolution treatment ...efficiently dissolved the PLA core template and exclusively yielded hollow silica spheres with a shell thickness of 16 ± 1 nm. The collected PLA could then be directly recycled from the template removal solution and reused to synthesize PLA nanoparticles for a next batch of hollow silica nanospheres. Such hollow particles are of interest in next-generation insulation materials and as lightweight fillers in polymers for fuel-efficient mobility.
Workup in organic synthesis can be very time-consuming, particularly when using reagents with both a solubility similar to that of the desired products and a tendency not to crystallize. In this ...respect, reactions involving organic bases would strongly benefit from a tremendously simplified separation process. Therefore, we synthesized a derivative of the superbasic proton sponge 1,8-bis(dimethylamino)naphthalene (DMAN) and covalently linked it to the strongest currently available nanomagnets based on carbon-coated cobalt metal nanoparticles. The immobilized magnetic superbase reagent was tested in Knoevenagel- and Claisen–Schmidt-type condensations and showed conversions of up to 99%. High yields of up to 97% isolated product could be obtained by simple recrystallization without using column chromatography. Recycling the catalyst was simple and fast with an insignificant decrease in catalytic activity.
Protein kinase C enzymes play an important role in signal transduction, regulation of gene expression and control of cell division and differentiation. The fsI and betaII isoenzymes result from the ...alternative splicing of the PKCbeta gene (PRKCB1), previously found to be associated with autism. We performed a family-based association study in 229 simplex and 5 multiplex families, and a postmortem study of PRKCB1 gene expression in temporocortical gray matter (BA41/42) of 11 autistic patients and controls. PRKCB1 gene haplotypes are significantly associated with autism (P<0.05) and have the autistic endophenotype of enhanced oligopeptiduria (P<0.05). Temporocortical PRKCB1 gene expression was reduced on average by 35 and 31% for the PRKCB1-1 and PRKCB1-2 isoforms (P<0.01 and <0.05, respectively) according to qPCR. Protein amounts measured for the PKCbetaII isoform were similarly decreased by 35% (P=0.05). Decreased gene expression characterized patients carrying the 'normal' PRKCB1 alleles, whereas patients homozygous for the autism-associated alleles displayed mRNA levels comparable to those of controls. Whole genome expression analysis unveiled a partial disruption in the coordinated expression of PKCbeta-driven genes, including several cytokines. These results confirm the association between autism and PRKCB1 gene variants, point toward PKCbeta roles in altered epithelial permeability, demonstrate a significant downregulation of brain PRKCB1 gene expression in autism and suggest that it could represent a compensatory adjustment aimed at limiting an ongoing dysreactive immune process. Altogether, these data underscore potential PKCbeta roles in autism pathogenesis and spur interest in the identification and functional characterization of PRKCB1 gene variants conferring autism vulnerability.
PDF
