Student-teacher socioemotional interactions, student’s focus of attention and emotional arousal in environmentally sensitive students

Literature has shown how student-teacher interaction influence children’s wellbeing and learning. Such interactions may also capture bystanders’ attention causing emotional arousal and taking away the focus of attention form the assigned task. The present study assessed the relation between student-teacher socioemotional interactions, student’s focus of attention and emotional arousal also accounting for environmental sensitivity. Through an eye tracker apparatus, we registered 95 primary school children’s pupil diameters while watching a student-teacher interaction scene. Sympathetic response and focus of attention were registered while different interaction scenes took place. Children self-reported on environmental sensitivity and perceived classroom climate. A mixed effects regression model for second pass pupil dilatation showed that attention was captured by different scenes based on their previous classroom experiences. The sympathetic response-attention link was moderated by environmental sensitivity. More sensitive children were more emotionally aroused when looking at the teacher scolding a sad child or a kind teacher having a child respond to her aggressively. Incongruent socio-emotional exchanges caused grater arousal in highly sensitive children compared to low sensitive ones. Based on the finding we planned an intervention to promote emotionally positive and in-tune teacher-student interactions to avoid students’ distraction and sympathetic arousal, especially in more environmentally sensitive students

Binding and Uptake into Human Hepatocellular Carcinoma Cells of Peptide-Functionalized Gold Nanoparticles

One of the most daunting challenges of nanomedicine is the finding of appropriate targeting agents to deliver suitable payloads precisely to cells affected by malignancies. Even more complex is to achieve the ability to ensure the nanosystems enter those cells. Here we use 2 nm (metal core) gold nanoparticles to target human hepatocellular carcinoma (HepG2) cells stably transfected with the SERPINB3 (SB3) protein. The nanoparticles were coated with a 85:15 mixture of thiols featuring, respectively, a phosphoryl choline, to ensure water solubility and biocompatibility, and a 28-mer peptide corresponding to the amino acid sequence 21-47 of the hepatitis B virus-PreS1 protein (PreS1(21-47)). Conjugation of the peptide was performed via the maleimide-thiol reaction in methanol allowing the use of a limited amount of the targeting molecule. This is an efficient procedure also in the perspective of selecting libraries of new targeting agents. The rationale behind the selection of the peptide is that SB3, which is undetectable in normal hepatocytes, is over-expressed in hepatocellular carcinoma and in hepatoblastoma and has been proposed as a target of the hepatitis B virus (HBV). For the latter the key recognition element is the PreS1(21-47) peptide, which is a fragment of one of the proteins composing the viral envelope. The ability of the conjugated nanoparticles to bind the target protein SB3, expressed in liver cancer cells, was investigated by surface plasmon resonance analysis and in vitro via cellular uptake analysis followed by atomic absorption analysis of digested samples. The results showed that the PreS1(21-47) peptide is a suitable targeting agent for cells overexpressing the SB3 protein. Even more important is the evidence that the gold nanoparticles are internalized by the cells. The comparison between the surface plasmon resonance analysis and the cellular uptake studies suggests the presentation of the protein on cell surface is critical for efficient recognition

Synthesis, Interfaces, and Nanostructures: A Section of Nanomaterials (ISSN 2079-4991)

“Synthesis, Interfaces, and Nanostructures” is one of the pillar sections of Nanomaterials and has contributed to the significant increase in the journal’s recognition by the scientific community, boosting its Impact Factor to 5 [...

Special Issue “Synthesis and Applications of Functionalized Gold Nanosystems”

When I launched this Special Issue, I wrote: “Gold-based nanosystems are among the most interesting systems in the nanoworld because of their broad spectrum of applications, ranging from analyte detection to nanomedicine and the mimicry of enzymes, just to mention a few examples [...

Metallomicelles as catalysts of the hydrolysis of carboxylic and phosphoric acid esters

Lipophilic ligands 2-4 have been synthesized. In the presence of Cu(II) ions, they form metallomicelles that are catalytically active in the cleavage of the p-nitrophenyl esters of acetic, hexanoic, and dodecanoic acids. Catalysis was also observed in the cleavage of p-nitrophenyl diphenyl phosphate. The apparent pK(a) of the Cu(II)-coordinated hydroxyl of ligand 2a, in the micellar aggregate, is 7.7, as estimated from the rate vs pH profiles for both classes of esters: this suggests that the hydroxyl is involved as a nucleophile in the hydrolytic cleavage, which proved to be really catalytic process. The ligand bearing the free hydroxyl (2a) is more effective in the cleavage of carboxylate esters than ligands with the methylated alcoholic group (2b) or devoid of it (4); the opposite behavior is observed in the cleavage of the phosphate triester. A rationale is offered that calls for the difference in the coordination ability to the metal center of phosphate and carboxylate esters

Leaving group effect in the cleavage of picolinate esters catalyzed by hydroxy-functionalized metallomicelles

Micellar aggregates of complexes of transition metal ions with the hydroxy-functionalized surfactant 1a are very effective catalysts of the cleavage of activated esters of alpha-amino acids. To ascertain their effectiveness toward unactivated esters, a systematic kinetic study was undertaken employing as substrates the picolinic acid esters 3a-1, the pK(a) of their alcoholic portion spanning more than 12 units from 3.6 to 16. The leaving group effect was investigated in water, pH=6.3, in the absence and presence of CU2+ ions, in the presence of the nonmicellar complex 2-CU2+, and in the presence of micellar aggregates made of 1a-Cu2+ or of its O-methylated analog 1b-Cu2+. In the presence of free metal ions the leaving group effect is negligible in the case of esters with good leaving groups (pK(a)<ca. 12), and it becomes remarkably large in that of,unactivated substrates. In the presence of CU2+ complexes, either micellar la or nonmicellar 2, the leaving group effect is relatively small in the case of activated substrates (pK(a)<9, 1a; pK(a)<11, 2) and sharply increases in the case of unactivated substrates. A similar trend was observed in a less extensive kinetic investigation using Zn2+ ions at pH=7.5. The largest rate enhancements were observed in the case of the most activated substrates in micellar solutions of the 1a-Cu2+ complex (1.6x10(6) folds for 3b over the rate in pure buffer), considerably larger than those in the presence of its nonmicellar analog (4.2X10(4) folds) or of the free metal ion (1.5X10(3) folds). However, in the case of unactivated esters, such kinetic benefits vanish out and the metal ion alone is even more effective (2x10(4) folds acceleration for 31 in presence of CU2+) than its complexes, either in the monomeric (7.3x10(3) folds) or in the micellar form (4.6x10(3) folds). On the basis of the possible changes in the mechanistic pathway depending on the nature of the leaving group, a rationale is offered

Chiral Lipophilic Ligands. 1. Enantioselective Cleavage of .alpha.-Amino Acid Esters in Metallomicellar Aggregates

Several chiral ligands (1a,b, 2a-d), their marked lipophilic structure featuring a binding subunit comprising a 2-substituted pyridine, a tertiary amine, and a hydroxyl, have been synthesized and their complexes with Cu(II), Zn(II), or Co(II) ions investigated in homomicellar or comicellar aggregates as enantioselective catalysts of the cleavage of p-nitrophenyl esters of alpha-amino acids (Phe, Phg, Leu). Rate accelerations up to 3 orders of magnitude over the Cu(II) catalyzed hydrolysis and enantioselectivities ranging from; 3.2 to 11.6 have been observed. In each case explored, the chiral ligand reacts faster with the enantiomeric substrate of opposite absolute configuration. Several pieces of evidence indicate that the effective cleavage process in micellar aggregates involves the following: (a) the formation of a ternary (ligand-metal ion-substrate) complex; (b) within such a complex, a nucleophilic attack of the ligand hydroxyl on the substrate to give a transacylation intermediate; and (c) the metal ion promoted hydrolysis of the transacylation intermediate with a relatively fast turnover of the catalyst. Such a mode of action does not operate outside or in the absence of micellar aggregates: in this case; the hydroxyl is displaced by water that acts as the nucleophile ina slower (less enantioselective) process. The enantioselectivity of the transacylation process appears to be little affected by the steric interaction between the substituents at the chiral center of the amino acid ester and of the ligand. We suggest that the enantioselectivity arises from a different hydration, due to steric reasons, of the diastereomeric complexes comprising the two enantiomers of the substrate. As a consequence, the relevance of the competing mechanisms of cleavage of the ester, the first one, faster, involving the hydroxyl and the second one, slower, involving a Cu(II)-bound water molecule, may be different. In the case of the less hydrated, more hydrophobic R-S or S-R complex the former, faster, mode of cleavage may be more relevant than in the case of the more hydrated, less hydrophobic, S-S or R-R complex