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Porcu S, Corpino R, Carbonaro CM, Ricci PC, Vargiu AV, Sanna AL, Sforazzini G, Chiriu D. Promising Molecular Architectures for Two-Photon Probes in the Diagnosis of α-Synuclein Aggregates. Molecules 2024; 29:2817. [PMID: 38930882 PMCID: PMC11207056 DOI: 10.3390/molecules29122817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 05/24/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
The abnormal deposition of protein in the brain is the central factor in neurodegenerative disorders (NDs). These detrimental aggregates, stemming from the misfolding and subsequent irregular aggregation of α-synuclein protein, are primarily accountable for conditions such as Parkinson's disease, Alzheimer's disease, and dementia. Two-photon-excited (TPE) probes are a promising tool for the early-stage diagnosis of these pathologies as they provide accurate spatial resolution, minimal intrusion, and the ability for prolonged observation. To identify compounds with the potential to function as diagnostic probes using two-photon techniques, we explore three distinct categories of compounds: Hydroxyl azobenzene (AZO-OH); Dicyano-vinyl bithiophene (DCVBT); and Tetra-amino phthalocyanine (PcZnNH2). The molecules were structurally and optically characterized using a multi-technique approach via UV-vis absorption, Raman spectroscopy, three-dimensional fluorescence mapping (PLE), time-resolved photoluminescence (TRPL), and pump and probe measurements. Furthermore, quantum chemical and molecular docking calculations were performed to provide insights into the photophysical properties of the compounds as well as to assess their affinity with the α-synuclein protein. This innovative approach seeks to enhance the accuracy of in vivo probing, contributing to early Parkinson's disease (PD) detection and ultimately allowing for targeted intervention strategies.
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Affiliation(s)
- Stefania Porcu
- Department of Physics, University of Cagliari, Cittadella Universitaria, SP n°8, 09042 Monserrato, CA, Italy; (S.P.); (R.C.); (C.M.C.); (P.C.R.); (A.V.V.)
| | - Riccardo Corpino
- Department of Physics, University of Cagliari, Cittadella Universitaria, SP n°8, 09042 Monserrato, CA, Italy; (S.P.); (R.C.); (C.M.C.); (P.C.R.); (A.V.V.)
| | - Carlo Maria Carbonaro
- Department of Physics, University of Cagliari, Cittadella Universitaria, SP n°8, 09042 Monserrato, CA, Italy; (S.P.); (R.C.); (C.M.C.); (P.C.R.); (A.V.V.)
| | - Pier Carlo Ricci
- Department of Physics, University of Cagliari, Cittadella Universitaria, SP n°8, 09042 Monserrato, CA, Italy; (S.P.); (R.C.); (C.M.C.); (P.C.R.); (A.V.V.)
| | - Attilio Vittorio Vargiu
- Department of Physics, University of Cagliari, Cittadella Universitaria, SP n°8, 09042 Monserrato, CA, Italy; (S.P.); (R.C.); (C.M.C.); (P.C.R.); (A.V.V.)
| | - Anna Laura Sanna
- Department of Chemistry and Hearth Science, University of Cagliari, Cittadella Universitaria, SP n°8, 09042 Monserrato, CA, Italy;
| | - Giuseppe Sforazzini
- Department of Chemistry and Hearth Science, University of Cagliari, Cittadella Universitaria, SP n°8, 09042 Monserrato, CA, Italy;
| | - Daniele Chiriu
- Department of Physics, University of Cagliari, Cittadella Universitaria, SP n°8, 09042 Monserrato, CA, Italy; (S.P.); (R.C.); (C.M.C.); (P.C.R.); (A.V.V.)
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Olla C, Cappai A, Porcu S, Stagi L, Fantauzzi M, Casula MF, Mocci F, Corpino R, Chiriu D, Ricci PC, Carbonaro CM. Exploring the Impact of Nitrogen Doping on the Optical Properties of Carbon Dots Synthesized from Citric Acid. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:1344. [PMID: 37110929 PMCID: PMC10141696 DOI: 10.3390/nano13081344] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 04/07/2023] [Accepted: 04/09/2023] [Indexed: 06/19/2023]
Abstract
The differences between bare carbon dots (CDs) and nitrogen-doped CDs synthesized from citric acid as a precursor are investigated, aiming at understanding the mechanisms of emission and the role of the doping atoms in shaping the optical properties. Despite their appealing emissive features, the origin of the peculiar excitation-dependent luminescence in doped CDs is still debated and intensively being examined. This study focuses on the identification of intrinsic and extrinsic emissive centers by using a multi-technique experimental approach and computational chemistry simulations. As compared to bare CDs, nitrogen doping causes the decrease in the relative content of O-containing functional groups and the formation of both N-related molecular and surface centers that enhance the quantum yield of the material. The optical analysis suggests that the main emission in undoped nanoparticles comes from low-efficient blue centers bonded to the carbogenic core, eventually with surface-attached carbonyl groups, the contribution in the green range being possibly related to larger aromatic domains. On the other hand, the emission features of N-doped CDs are mainly due to the presence of N-related molecules, with the computed absorption transitions calling for imidic rings fused to the carbogenic core as the potential structures for the emission in the green range.
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Affiliation(s)
- Chiara Olla
- Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
| | - Antonio Cappai
- Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
| | - Stefania Porcu
- Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
| | - Luigi Stagi
- Laboratory of Materials Science and Nanotechnology, CR-INSTM, Department of Chemical, Physics, Mathematics and Natural Sciences, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
| | - Marzia Fantauzzi
- Department of Chemistry and Geological Science, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
| | - Maria Francesca Casula
- Department of Mechanical, Chemical, and Materials Engineering, CINSA and INSTM, University of Cagliari, Via Marengo 2, I-09123 Cagliari, Italy
| | - Francesca Mocci
- Department of Chemistry and Geological Science, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
| | - Riccardo Corpino
- Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
| | - Daniele Chiriu
- Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
| | - Pier Carlo Ricci
- Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
| | - Carlo Maria Carbonaro
- Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
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Olla C, Ricci PC, Chiriu D, Fantauzzi M, Casula MF, Mocci F, Cappai A, Porcu S, Stagi L, Carbonaro CM. Selecting molecular or surface centers in carbon dots-silica hybrids to tune the optical emission: A photo-physics study down to the atomistic level. J Colloid Interface Sci 2023; 634:402-417. [PMID: 36542970 DOI: 10.1016/j.jcis.2022.12.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 12/01/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022]
Abstract
In this work, we unveil the fluorescence features of citric acid and urea-based Carbon Dots (CDs) through a photo-physical characterization of nanoparticles synthesized, under solvent-free and open-air conditions, within silica-ordered mesoporous silica, as a potential host for solid-state emitting hybrids. Compared to CDs synthesized without silica matrices and dispersed in water, silica-CD hybrids display a broader emission in the green range whose contribution can be increased by UV and blue laser irradiation. The analysis of hybrids synthesized within different silica (MCM-48 and SBA-15) calls for an active role of the matrix in directing the synthesis toward the formation of CDs with a larger content of graphitic N and imidic groups at the expense of N-pyridinic molecules. As a result, CDs tuned in size and with a larger green emission are obtained in the hybrids and are retained once extracted from the silica matrix and dispersed in water. The kinetics of the photo-physics under UV and blue irradiation of hybrid samples show a photo-assisted formation process leading to a further increase of the relative contribution of the green emission, not observed in the water-dispersed reference samples, suggesting that the porous matrix is involved also in the photo-activated process. Finally, we carried out DFT and TD-DFT calculations on the interaction of silica with selected models of CD emitting centers, like surface functional groups (OH and COOH), dopants (graphitic N), and citric acid-based molecules. The combined experimental and theoretical results clearly indicate the presence of molecular species and surface centers both emitting in the blue and green spectral range, whose relative contribution is tuned by the interaction with the surrounding media.
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Affiliation(s)
- Chiara Olla
- Department of Physics, University of Cagliari, I-09042 Monserrato, Italy.
| | - Pier Carlo Ricci
- Department of Physics, University of Cagliari, I-09042 Monserrato, Italy
| | - Daniele Chiriu
- Department of Physics, University of Cagliari, I-09042 Monserrato, Italy
| | - Marzia Fantauzzi
- Department of Chemical and Geological Sciences, University of Cagliari, I-09042 Monserrato, Italy
| | - Maria Francesca Casula
- Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, Via Marengo 2, I-09123 Cagliari, Italy
| | - Francesca Mocci
- Department of Chemical and Geological Sciences, University of Cagliari, I-09042 Monserrato, Italy
| | - Antonio Cappai
- Department of Physics, University of Cagliari, I-09042 Monserrato, Italy
| | - Stefania Porcu
- Department of Physics, University of Cagliari, I-09042 Monserrato, Italy
| | - Luigi Stagi
- Department of Chemistry and Pharmacy, Laboratory of Materials Science and Nanotechnology, University of Sassari, Via Vienna 2, I-07100 Sassari, Italy
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Kasprzyk W, Świergosz T, Romańczyk PP, Feldmann J, Stolarczyk JK. The role of molecular fluorophores in the photoluminescence of carbon dots derived from citric acid: current state-of-the-art and future perspectives. NANOSCALE 2022; 14:14368-14384. [PMID: 36156633 DOI: 10.1039/d2nr03176k] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Carbon dots (CDs), an emerging class of nanomaterials, have attracted considerable attention due to their intriguing photophysical properties. Despite their indisputable potential of utilization in many fascinating areas of research and life, some fundamental aspects concerning their structure and the origin of their photoluminescence (PL) properties still await clarification. The mechanism of PL emission of CDs is associated with their structure, which is dependent on the carbonization process. At the initial stages of CD synthesis via a bottom-up approach, molecular fluorophores are considered to dominate the optical characteristics of the resulting nanomaterials. In this review, the recent progress in the use of molecular state theory for explanation of the structure-property relationship in CDs is summarized. This review focuses exclusively on the molecular fluorophores existing in nanomaterials prepared from citric acid (CA) as one of the most frequent carbon sources reported for the bottom-up synthesis of CDs. Consequently, the most relevant transformations of CA and the history of molecular fluorophores derived from it are described, followed by an in-depth discussion on their relevance in understanding the specific photophysical properties of blue-, green-, and red-emitting CDs. Finally, the challenging issues and future perspectives of molecular state PL mechanism exploration in CDs are highlighted.
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Affiliation(s)
- Wiktor Kasprzyk
- Department of Biotechnology and Physical Chemistry, Faculty of Chemical Engineering and Technology, Cracow University of Technology, Warszawska 24, 31-155 Kraków, Poland.
| | - Tomasz Świergosz
- Department of Chemical Technology and Environmental Analysis, Faculty of Chemical Engineering and Technology, Cracow University of Technology, Warszawska 24, 31-155 Kraków, Poland
| | - Piotr P Romańczyk
- Department of Biotechnology and Physical Chemistry, Faculty of Chemical Engineering and Technology, Cracow University of Technology, Warszawska 24, 31-155 Kraków, Poland.
| | - Jochen Feldmann
- Chair for Photonics and Optoelectronics, Nano-Institute Munich, Department of Physics, Ludwig-Maximilians-Universität München, Königinstrasse 10, Munich, 80539, Germany
| | - Jacek K Stolarczyk
- Chair for Photonics and Optoelectronics, Nano-Institute Munich, Department of Physics, Ludwig-Maximilians-Universität München, Königinstrasse 10, Munich, 80539, Germany
- Smoluchowski Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
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Mocci F, de Villiers Engelbrecht L, Olla C, Cappai A, Casula MF, Melis C, Stagi L, Laaksonen A, Carbonaro CM. Carbon Nanodots from an In Silico Perspective. Chem Rev 2022; 122:13709-13799. [PMID: 35948072 PMCID: PMC9413235 DOI: 10.1021/acs.chemrev.1c00864] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Carbon nanodots (CNDs) are the latest and most shining rising stars among photoluminescent (PL) nanomaterials. These carbon-based surface-passivated nanostructures compete with other related PL materials, including traditional semiconductor quantum dots and organic dyes, with a long list of benefits and emerging applications. Advantages of CNDs include tunable inherent optical properties and high photostability, rich possibilities for surface functionalization and doping, dispersibility, low toxicity, and viable synthesis (top-down and bottom-up) from organic materials. CNDs can be applied to biomedicine including imaging and sensing, drug-delivery, photodynamic therapy, photocatalysis but also to energy harvesting in solar cells and as LEDs. More applications are reported continuously, making this already a research field of its own. Understanding of the properties of CNDs requires one to go to the levels of electrons, atoms, molecules, and nanostructures at different scales using modern molecular modeling and to correlate it tightly with experiments. This review highlights different in silico techniques and studies, from quantum chemistry to the mesoscale, with particular reference to carbon nanodots, carbonaceous nanoparticles whose structural and photophysical properties are not fully elucidated. The role of experimental investigation is also presented. Hereby, we hope to encourage the reader to investigate CNDs and to apply virtual chemistry to obtain further insights needed to customize these amazing systems for novel prospective applications.
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Affiliation(s)
- Francesca Mocci
- Department
of Chemical and Geological Sciences, University
of Cagliari, I-09042 Monserrato, Italy,
| | | | - Chiara Olla
- Department
of Physics, University of Cagliari, I-09042 Monserrato, Italy
| | - Antonio Cappai
- Department
of Physics, University of Cagliari, I-09042 Monserrato, Italy
| | - Maria Francesca Casula
- Department
of Mechanical, Chemical and Materials Engineering, University of Cagliari, Via Marengo 2, IT 09123 Cagliari, Italy
| | - Claudio Melis
- Department
of Physics, University of Cagliari, I-09042 Monserrato, Italy
| | - Luigi Stagi
- Department
of Chemistry and Pharmacy, Laboratory of Materials Science and Nanotechnology, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
| | - Aatto Laaksonen
- Department
of Chemical and Geological Sciences, University
of Cagliari, I-09042 Monserrato, Italy,Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden,State Key
Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 210009, P. R. China,Centre
of Advanced Research in Bionanoconjugates and Biopolymers, PetruPoni Institute of Macromolecular Chemistry, Aleea Grigore Ghica-Voda 41A, 700487 Iasi, Romania,Division
of Energy Science, Energy Engineering, Luleå
University of Technology, Luleå 97187, Sweden,
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Dhamodharan D, Byun HS, Varsha Shree M, Veeman D, Natrayan L, Stalin B. Carbon Nanodots: Synthesis, Mechanisms for Bio-electrical Applications. J IND ENG CHEM 2022. [DOI: 10.1016/j.jiec.2022.03.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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7
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Olla C, Porcu S, Secci F, Ricci PC, Carbonaro CM. Towards N-N-Doped Carbon Dots: A Combined Computational and Experimental Investigation. MATERIALS 2022; 15:ma15041468. [PMID: 35208012 PMCID: PMC8880414 DOI: 10.3390/ma15041468] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/27/2022] [Accepted: 02/09/2022] [Indexed: 02/04/2023]
Abstract
The introduction of N doping atoms in the carbon network of Carbon Dots is known to increase their quantum yield and broaden the emission spectrum, depending on the kind of N bonding introduced. N doping is usually achieved by exploiting amine molecules in the synthesis. In this work, we studied the possibility of introducing a N–N bonding in the carbon network by means of hydrothermal synthesis of citric acid and hydrazine molecules, including hydrated hydrazine, di-methylhydrazine and phenylhydrazine. The experimental optical features show the typical fingerprints of Carbon Dots formation, such as nanometric size, excitation dependent emission, non-single exponential decay of photoluminescence and G and D vibrational bands in the Raman spectra. To explain the reported data, we performed a detailed computational investigation of the possible products of the synthesis, comparing the simulated absorbance spectra with the experimental optical excitation pattern. The computed Raman spectra corroborate the hypothesis of the formation of pyridinone derivatives, among which the formation of small polymeric chains allowed the broad excitation spectra to be experimentally observed.
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Affiliation(s)
- Chiara Olla
- Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy; (S.P.); (P.C.R.)
- Correspondence: (C.O.); (C.M.C.)
| | - Stefania Porcu
- Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy; (S.P.); (P.C.R.)
| | - Francesco Secci
- Department of Chemistry and Geological Science, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy;
| | - Pier Carlo Ricci
- Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy; (S.P.); (P.C.R.)
| | - Carlo Maria Carbonaro
- Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy; (S.P.); (P.C.R.)
- Correspondence: (C.O.); (C.M.C.)
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