We report the nontemplated colloidal synthesis of single crystal CsPbBr3 perovskite nanosheets with lateral sizes up to a few micrometers and with thickness of just a few unit cells (i.e., below 5 nm), hence in the strong quantum confinement regime, by introducing short ligands (octanoic acid and octylamine) in the synthesis together with longer ones (oleic acid and oleylamine). The lateral size is tunable by varying the ratio of shorter ligands over longer ligands, while the thickness is mainly unaffected by this parameter and stays practically constant at 3 nm in all the syntheses conducted at short-to-long ligands volumetric ratio below 0.67. Beyond this ratio, control over the thickness is lost and a multimodal thickness distribution is observed.

In this work is presented a new category of self-growing, fibrous, natural composite materials with controlled physical properties that can be produced in large quantities and over wide areas, based on mycelium, the main body of fungi. Mycelia from two types of edible, medicinal fungi, Ganoderma lucidum and Pleurotus ostreatus, have been carefully cultivated, being fed by two bio-substrates: cellulose and cellulose/potato-dextrose, the second being easier to digest by mycelium due to presence of simple sugars in its composition. After specific growing times the mycelia have been processed in order to cease their growth. Depending on their feeding substrate, the final fibrous structures showed different relative concentrations in polysaccharides, lipids, proteins and chitin. Such differences are reflected as alterations in morphology and mechanical properties. The materials grown on cellulose contained more chitin and showed higher Young’s modulus and lower elongation than those grown on dextrose-containing substrates, indicating that the mycelium materials get stiffer when their feeding substrate is harder to digest. All the developed fibrous materials were hydrophobic with water contact angles higher than 120°. The possibility of tailoring mycelium materials’ properties by properly choosing their nutrient substrates paves the way for their use in various scale applications.

We report the colloidal synthesis of strongly fluorescent CsPbBr 3 perovskite nanowires (NWs) with rectangular section and with tuneable width, from 20 nm (exhibiting no quantum confinement, hence emitting in the green) down to around 3 nm (in the strong quantumconfinement regime, emitting in the blue), by introducing in the synthesis a short acid (octanoic acid or hexanoic acid) together with alkyl amines (octylamine and oleylamine). Temperatures below 70 °C promoted the formation of monodisperse, few unit cell thick NWs that were free from byproducts. The photoluminescence quantum yield of the NW samples went from 12% for non-confined NWs emitting at 524 nm to a maximum of 77% for the 5 nm diameter NWs emitting at 497 nm, down to 30% for the thinnest NWs (diameter ~ 3nm), in the latter sample most likely due to aggregation occurring in solution.

The mechanism of neurodegeneration caused by ␤-amyloid in Alzheimer disease is controversial. Neuronal toxicity is exerted mostly by various species of soluble ␤-amyloid oligomers that differ in their N-and C-terminal domains. However, abundant accumulation of ␤-amyloid also occurs in the brains of cognitively normal elderly people, in the absence of obvious neuronal dysfunction. We postulated that neuronal toxicity depends on the molecular composition, rather than the amount, of the soluble ␤-amyloid oligomers. Here we show that soluble ␤-amyloid aggregates that accumulate in Alzheimer disease are different from those of normal aging in regard to the composition as well as the aggregation and toxicity properties.A series of evidence indicates that progressive cerebral accumulation of ␤-amyloid (A␤), 2 a proteolytic product of transmembrane protein APP, is the primary pathogenic event of Alzheimer disease (AD) (1). Recent clues indicate that small, soluble A␤ aggregates produce more severe synaptic dysfunction and neuronal damage than do A␤ polymers (2-5). This behavior is common to all known pathogenic and nonpathogenic amyloidogenic peptides (6, 7). Soluble A␤ is detectable early in the cerebral cortex of subjects at risk for AD pathology, several years before the formation and deposition of amyloid fibrils (8). Hence, the analysis of soluble A␤ in brain tissue allows the characterization of the toxic form of the peptide.A strong argument against the amyloid hypothesis is the abundant and constant deposition of A␤ in the brains of elderly subjects, in the absence of signs of neuronal degeneration and dementia (9 -11). The reasons for the absence of pathogenic effect exerted by A␤ in normal aging are unknown. The issue has important therapeutic implications, because the major strategies to prevent and cure AD are focused on halting A␤ accumulation (12).In brains from Alzheimer disease (AD) and Down syndrome patients, three major species of soluble A␤ have been identified by mass spectrometry: the full-length form, A␤1-42, which has a relative molecular mass of 4.5 kDa, and two N-terminal peptides truncated at residue 3 (A␤3-42) and residue 11 (A␤11-42) with relative molecular masses of 4.2 and 3.5 kDa, respectively (13, 14). The 4.2-and 3.5-kDa bands are more prominent in familial AD carrying presenilin 1 mutations than in sporadic AD, suggesting that the ratio of soluble A␤ species may dictate the toxicity of the aggregates (15).We predicted that the composition of soluble A␤ underlies the different effect exerted by the molecule in AD and in normal aging. To investigate this hypothesis, we studied the composition and properties of aggregation and toxicity as well as the damage produced on artificial membranes of soluble A␤, comparing these areas in sporadic AD and cognitively normal elderly subjects with abundant amyloid plaques in cerebral cortex. MATERIALS AND METHODSTissues-We used frozen blocks and formalin-fixed sections of frontal cortex from 14 cases with late onset sporadic AD (mean age at death 80 Ϯ ...

Dialysis-related amyloidosis is characterized by the deposition of insoluble fibrils of ␤ 2 -microglobulin (␤ 2 -m) in the musculoskeletal system. Atomic force microscopy inspection of ex vivo amyloid material reveals the presence of bundles of fibrils often associated to collagen fibrils. Aggregation experiments were undertaken in vitro with the aim of reproducing the physiopathological fibrillation process. To this purpose, atomic force microscopy, fluorescence techniques, and NMR were employed. We found that in temperature and pH conditions similar to those occurring in periarticular tissues in the presence of flogistic processes, ␤ 2 -m fibrillogenesis takes place in the presence of fibrillar collagen, whereas no fibrils are obtained without collagen. Moreover, the morphology of ␤ 2 -m fibrils obtained in vitro in the presence of collagen is extremely similar to that observed in the ex vivo sample. This result indicates that collagen plays a crucial role in ␤ 2 -m amyloid deposition under physiopathological conditions and suggests an explanation for the strict specificity of dialysis-related amyloidosis for the tissues of the skeletal system. We hypothesize that positively charged regions along the collagen fiber could play a direct role in ␤ 2 -m fibrillogenesis. This hypothesis is sustained by aggregation experiments performed by replacing collagen with a poly-L-lysine-coated mica surface. As shown by NMR measurements, no similar process occurs when poly-L-lysine is dissolved in solution with ␤ 2 -m. Overall, the findings are consistent with the estimates resulting from a simplified collagen model whereby electrostatic effects can lead to high local concentrations of oppositely charged species, such as ␤ 2 -m, that decay on moving away from the fiber surface.The deposition of ␤ 2 -microglobulin (␤ 2 -m) 2 into amyloid fibrils is the hallmark of dialysis-related amyloidosis (DRA), a disease arising as a complication of long-term hemodialysis. ␤ 2 -m is a 99-residue protein (molecular mass 11.7 kDa) that represents the light chain of the major histocompatibility complex class I (MHCI), an integral membrane protein involved in the immune response. As a result of normal MHCI catabolism, ␤ 2 -m is released in the serum from the cell surface and carried to the kidney for clearance. In the presence of kidney failure, the concentration of free circulating ␤ 2 -m can increase by up to 50-fold; the persistent increase in ␤ 2 -m concentration results in amyloid deposition, preferentially localized in the musculoskeletal system. The accumulation of ␤ 2 -m deposits has been shown to cause arthralgias, destructive osteoarthropathies, and carpal tunnel syndrome (1). Although a high concentration of ␤ 2 -m is a necessary condition for the onset of the disease, there is not a strict correlation between the disease severity and ␤ 2 -m levels (2), suggesting that other factors might be involved in ␤ 2 -m amyloid deposition.The aggregation process of ␤ 2 -m has been the object of extensive investigation for many years. Severa...