Laser synthesis emerges as a suitable technique to produce ligand-free nanoparticles, alloys and functionalized nanomaterials for catalysis, imaging, biomedicine, energy and environmental applications. In the last decade, laser ablation and nanoparticle generation in liquids has proven to be a unique and efficient technique to generate, excite, fragment and conjugate a large variety of nanostructures in a scalable and clean way. In this work, we give an overview on the fundamentals of pulsed laser synthesis of nanocolloids and new information about its scalability towards selected applications. Biomedicine, catalysis and sensing are the application areas mainly discussed in this review, highlighting advantages of laser-synthesized nanoparticles for these types of applications and, once partially resolved, the limitations to the technique for large-scale applications.
We report a structural investigation on IAPP, Aβ(1-40) and their equi-molar mixture aggregation pathway at nano-molar concentration using the Surface Enhanced Raman Spectroscopy (SERS) effect induced by silver metal colloids prepared by laser processes in solution and molecular dynamics simulations. Our data show the ability of silver NPs coupled with SERS to detect secondary structures of IAPP, Aβ(1-40) and their 1 : 1 molar ratio mixture in the oligomeric state. The preparation of silver colloids shows superior performance with respect to chemically prepared nano-particles. SERS spectroscopy shows both selectivity and sensitivity in detecting the secondary structures of hIAPP and Aβ(1-40) and to recognize both proteins in their mixture. On the other hand, molecular dynamics simulations confirm SERS structural data and the given atomistic details about the structural organization of IAPP and Aβ(1-40) oligomers. Our study shows an inhomogeneity in the chemical composition of IAPP/Aβ(1-40) oligomer aggregates.
The three GxxxG repeating motifs from the C-terminal region of β-amyloid (Aβ) peptide play a significant role in regulating the aggregation kinetics of the peptide. Mutation of these glycine residues to leucine greatly accelerates the fibrillation process but generates a varied toxicity profile. Using an array of biophysical techniques, we demonstrated the uniqueness of the composite glycine residues in these structural repeats. We used solvent relaxation NMR spectroscopy to investigate the role played by the surrounding water molecules in determining the corresponding aggregation pathway. Notably, the conformational changes induced by Gly 33 and Gly 37 mutations result in significantly decreased toxicity in a neuronal cell line. Our results indicate that G 33 xxxG 37 is the primary motif responsible for Aβ neurotoxicity, hence providing a direct structurefunction correlation. Targeting this motif, therefore, can be a promising strategy to prevent neuronal cell death associated with Alzheimer's and other related diseases, such as type II diabetes and Parkinson's. ROESY were 48 and 64, respectively. Data processing and analysis were carried out using Topspin TM v3.2 software (Bruker Biospin, Switzerland) and Sparky (https://www.cgl.ucsf.edu/home/sparky) software, respectively.
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