Angelo Nicosia graduated in Materials Chemistry (2017) focusing on Spontaneous Symmetry Breaking in PEGylated porphyrin derivatives and the effect of building block structure, physical parameters and chirality induction. He received his PhD (2021) in Materials Science and Nanotechnology at the University of Catania, under the supervision of Prof. P. Mineo. His project related to polymer-based antibacterial coatings has received the “Best Solution Award” from EIT Health during the Translational Fellowship Program (2019). His research interests are related with polymer-based Graphene Oxide derivatives as well as porphyrin derivatives, for applications in antibacterial coatings, environmental remediation and optical sensing.
Among different depollution methods, photocatalysis activated by solar light is promising for ter... more Among different depollution methods, photocatalysis activated by solar light is promising for terrestrial outdoor applications. However, its use in underground structures and/or microgravity environments (e.g., extraterrestrial structures) is forbidden. In these cases, there are issues related to the energy emitted from the indoor lighting system because it is not high enough to promote the photocatalytic mechanism. Moreover, microgravity does not allow the recovery of the photocatalytic slurry from the depolluted solution. In this work, the synthesis of a filmable nanocomposite based on semiconductor nanoparticles supported by photosensitized copolyacrylates was performed through a bulk in situ radical copolymerization involving a photosensitizer macromonomer. The macromonomer and the nanocomposites were characterized through UV-Vis, fluorescence and NMR spectroscopies, gel permeation chromatography and thermogravimetric analysis. The photocatalytic activity of the sensitized nanoc...
In this study, graphene oxide (GO) and reduced-thiolated GO (rGOSH) were used as 2D substrate to ... more In this study, graphene oxide (GO) and reduced-thiolated GO (rGOSH) were used as 2D substrate to fabricate nanocomposites with nanoparticles of gold nanospheres (AuNS) or nanorods (AuNR), via in situ reduction of the metal salt precursor and seed-mediated growth processes. The plasmonic sensing capability of the gold-decorated nanosheets were scrutinized by UV-visible (UV-VIS) spectroscopy. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analyses (TGA), and atomic force microscopy (AFM) were performed in order to prove the actual reduction that occurred concomitantly with the thiolation of GO, the increase in the hydrophobic character as well as the size, and preferential gathering of the gold nanoparticles onto the nanosheet substrates, respectively. Moreover, the theoretical electronic and infrared absorption (UV-VIS and IR) spectra were calculated within a time-dependent approach of density functional theory (DFT). Eventually, in...
Photocatalytic remediation represents a potential sustainable solution to the abatement of xenobi... more Photocatalytic remediation represents a potential sustainable solution to the abatement of xenobiotic pollutants released within the water environment. Aeroxide® P25 titanium dioxide nanoparticles (TiO2 NPs) are well-known as one of the most efficient photocatalysts in several applications, and have also been investigated in water remediation as suspended powder. Recently, their application in the form of thin films has been revealed as a potential alternative to avoid time-consuming filtration processes. Polymers represent suitable substrates to immobilize TiO2 NPs, allowing further production of thin films that can be exploited as a photoactive coating for environmental remediation. Nevertheless, the methods adopted to immobilize TiO2 NPs on polymer matrix involve time-consuming procedures and the use of several reactants. Here, titanium dioxide-based nanocomposites (NCx) were obtained through a new approach based on Methyl Methacrylate in situ bulk polymerization and were compare...
This review arises from the need to rationalize the huge amount of information on the structural ... more This review arises from the need to rationalize the huge amount of information on the structural and spectroscopic properties of a peculiar class of porphyrin derivatives—the non-ionic PEGylated porphyrins—collected during almost two decades of research. The lack of charged groups in the molecular architecture of these porphyrin derivatives is the leitmotif of the work and plays an outstanding role in highlighting those interactions between porphyrins, or between porphyrins and target molecules (e.g., hydrophobic-, hydrogen bond related-, and coordination-interactions, to name just a few) that are often masked by stronger electrostatic contributions. In addition, it is exactly these weaker interactions between porphyrins that make the aggregated forms more prone to couple efficiently with external perturbative fields like weak hydrodynamic vortexes or temperature gradients. In the absence of charge, solubility in water is very often achieved by covalent functionalization of the porphyrin ring with polyethylene glycol chains. Various modifications, including of chain length or the number of chains, the presence of a metal atom in the porphyrin core, or having two or more porphyrin rings in the molecular architecture, result in a wide range of properties. These encompass self-assembly with different aggregate morphology, molecular recognition of biomolecules, and different photophysical responses, which can be translated into numerous promising applications in the sensing and biomedical field, based on turn-on/turn-off fluorescence and on photogeneration of radical species.
The Spontaneous Symmetry Breaking (SSB) phenomenon is a natural event in which a system changes i... more The Spontaneous Symmetry Breaking (SSB) phenomenon is a natural event in which a system changes its symmetric state, apparently reasonless, in an asymmetrical one. Nevertheless, this occurrence could be hiding unknown inductive forces. An intriguing investigation pathway uses supramolecular aggregates of suitable achiral porphyrins, useful to mimic the natural light-harvesting systems (as chlorophyll). Using as SSB probe supramolecular aggregates of 5,10,15,20-tetrakis[p(ω-methoxypolyethyleneoxy)phenyl]porphyrin (StarP), a non-ionic achiral PEGylated porphyrin, we explore here its interaction with weak asymmetric thermal gradients fields. The cross-correlation of the experimental data (circular dichroism, confocal microscopy, atomic force microscopy, and cryo-transmission electron microscopy) revealed that the used building blocks aggregate spontaneously, organizing in flag-like structures whose thermally-induced circular dichroism depends on their features. Finally, thermal gradien...
Silver nanoparticles (AgNPs) stand out over other metal nanoparticles thanks to their peculiar ba... more Silver nanoparticles (AgNPs) stand out over other metal nanoparticles thanks to their peculiar bactericidal and spectroscopic properties. Tunability of the AgNPs chemical–physical properties could be provided through their organic covalent coating. On the other hand, PEGylated porphyrin derivatives are versatile heteromacrocycles investigated for uses in the biomedical field as cytotoxic and tracking agents, but also as sensors. In this work, an easy multi-step approach was employed to produce coated silver nanoparticles. Specifically, the AgNPs were functionalized with 5,10,15-[p-(ω-methoxy-polyethyleneoxy)phenyl]-20-(p-hydroxyphenyl)-porphyrin (P(PEG350)3), using chloropropanethiol as a coupling agent. The P(PEG350)3 was structurally characterized through MALDI-TOF mass spectrometry, NMR spectroscopy and thermal analyses. The functionalization of AgNPs was monitored step-by-step employing UV-Vis spectroscopy, dynamic light scattering and thermogravimetric techniques. HRTEM and STE...
An effective and convenient protocol for the synthesis of 1-substituted uracil-6-carbaldehyde der... more An effective and convenient protocol for the synthesis of 1-substituted uracil-6-carbaldehyde derivatives has been developed. A three-step sequence permits the preparation of uracil-6-carbaldehydes with various substituents at the N-1 in large quantities by using low-cost precursors. The aldehyde-functionalized uracils served as useful precursors for the preparation of meso-(1-substituted 6-uracil)-derivatives of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY). In this way, regioselectively functionalized BODIPYs with a direct connection to a nucleobase were prepared in yields of 30–45%. MALDI-TOF mass spectrometry, NMR, UV/vis absorption, and steady-state and time-resolved fluorescence spectroscopies were used to characterize the structures and the spectroscopic/photophysical properties of the resultant dyes.
Nanocomposites obtained by the decoration of graphene-based materials with silver nanoparticles (... more Nanocomposites obtained by the decoration of graphene-based materials with silver nanoparticles (AgNPs) have received increasing attention owing to their antimicrobial activity. However, the complex synthetic methods for their preparation have limited practical applications. This study aims to synthesize novel NanoHybrid Systems based on graphene, polymer, and AgNPs (namely, NanoHy-GPS) through an easy microwave irradiation approach free of reductants and surfactants. The polymer plays a crucial role, as it assures the coating layer/substrate compatibility making the platform easily adaptable for a specific substrate. AgNPs’ loading (from 5% to 87%) can be tuned by the amount of Silver salt used during the microwave-assisted reaction, obtaining spherical AgNPs with average sizes of 5–12 nm homogeneously distributed on a polymer-graphene nanosystem. Interestingly, microwave irradiation partially restored the graphene sp2 network without damage of ester bonds. The structure, morpholog...
The decontamination of water containing toxic metals is a challenging problem, and in the last ye... more The decontamination of water containing toxic metals is a challenging problem, and in the last years many efforts have been undertaken to discover efficient, cost-effective, robust, and handy technology for the decontamination of downstream water without endangering human health. According to the World Health Organization (WHO), 180 million people in the world have been exposed to toxic levels of arsenic from potable water. To date, a variety of techniques has been developed to maintain the arsenic concentration in potable water below the limit recommended by WHO (10 μg/L). Recently, a series of technological advancements in water remediation has been obtained from the rapid development of nanotechnology-based strategies that provide a remarkable control over nanoparticle design, allowing the tailoring of their properties toward specific applications. Among the plethora of nanomaterials and nanostructures proposed in the remediation field, graphene-based materials (G), due to their ...
A recent approach in the treatment of diseased cells/tissues is the use of smart, stimuli-respons... more A recent approach in the treatment of diseased cells/tissues is the use of smart, stimuli-responsive nanomaterials. Well-known examples include photosensitizer agents that after light irradiation at a specific wavelength generate singlet oxygen species (strongly cytotoxic) or self-assembled supramolecular structures, which blow up cancer cells by releasing their payload upon an external stimulus, thus making cancer cells swell and burst (so-called “nanobombs”). In this work we synthesized and characterized a polymeric star-like pentaporphyrin system (5P) that, depending on the photoexcitation wavelength selected, can act either as a photosensitizer or as a nanobomb. The 5P compound was characterized by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, nuclear magnetic resonance, UV–vis, and fluorescence spectroscopy techniques. The hydrodynamic size of the 5P compound in physiological buffer solution, as determined by dynamic light spectroscopy, pointed to the formation o...
The main objective of supramolecular chemistry is to mimic the macrosystems present in nature, a ... more The main objective of supramolecular chemistry is to mimic the macrosystems present in nature, a goal that fits perfectly with the green chemistry guidelines.
Abstract The measure of the acid concentration in an organic media is a common issue in chemistry... more Abstract The measure of the acid concentration in an organic media is a common issue in chemistry. With the aim to overcome this problem in a facile and inexpensive way, the spectroscopic properties of a PEGylate porphyrin derivative, the 5,10,15,20-p-(ω-methoxypolyethyleneoxyphenyl) porphyrin (P), as an acidity sensor were tested. Its behaviour was analysed in toluene and several fuels through acid titration experiments. In each case, examining UV–vis and fluorescence spectroscopic data, the disappearance of the free-base porphyrin derivative Uv–vis signals (B- and Q-bands) and the increasing of new bands, as a consequence of the added acid, was monitored. On the basis of these data it was possible to evaluate the presence of acid in several organic media as toluene, gasoline, diesel, and jet fuel, using our porphyrin derivative in very low amount (about 3 ppm). Finally, in order to exclude the risk of a negative contribution of P in ash formation, the complete oxidation of the porphyrin compound under common engine's combustion conditions was also ascertained.
Abstract An innovative solvent- and catalyst-free procedure for the grafting of acetylene groups ... more Abstract An innovative solvent- and catalyst-free procedure for the grafting of acetylene groups on polylactic acid (PLA) backbone is reported, using propargylamine as alkyne donor. The synthetic protocol was tested at different PLA/propargylamine molar ratio and the efficiency was determined in terms of functionalization degree and molecular weights. The engineering of PLA by the green protocol introduces alkyne moieties and generates free hydroxyl groups that are exploited to increase the alkyne functionality by treatment with pent-4-ynoic anhydride. Alkyne-grafted PLA derivatives are useful building blocks for access to a variety of functionalized polymers by Cu(I)-catalyzed cycloaddition reaction (CuAAC) with azides derivatives. As a proof of principle, methoxypolyethylene glycol azide and azide-fluor 545 are selected as models of hydrophilic polymer and fluorescent probe, respectively.
Colloids and Surfaces A: Physicochemical and Engineering Aspects
Abstract Hybrid gold nanoparticles covalently coated with 5,10,15-p-(ω-methoxy polyethyleneoxyphe... more Abstract Hybrid gold nanoparticles covalently coated with 5,10,15-p-(ω-methoxy polyethyleneoxyphenyl)-20-p-(hydroxyphenyl) porphyrin molecules, having about 16 repetitive units in each of its poly(oxyethylene) branches, were synthesized and characterized by UV–vis, fluorescence, dynamic light scattering (DLS), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) measurements. Their [H3O+] optical sensing behavior was also studied and compared to that of the similar water-soluble star polymer 5,10,15,20-tetrakis p-[ω-methoxypoly(ethyleneoxy)]phenylporphyrin. Changing the pH of a solution, the UV–vis spectra of the PEGylate porphyrin gold nanoparticles conjugates showed the gradual disappearance of the Soret band at 424 nm and the progressive increase of a new band at 451 nm. Upon acidic titration, also the fluorescence spectra showed a gradual disappearing of the fluorescence at 654 nm. Moreover, an unusual B-Band red-shift and a decreasing of porphyrin core basicity were observed for this porphyrin bonded to the gold nanoparticle surfaces. To rationalize these phenomena an in silico TD-DFT calculation study was then conducted. For its properties, this new system: can be used in both aqueous and organic media; by a simple treatment of the solution at 80 °C under N2 gas stream the starting Soret signals can be recovered; the nanoparticles can be eventually removed from the solution by centrifugation.
Among different depollution methods, photocatalysis activated by solar light is promising for ter... more Among different depollution methods, photocatalysis activated by solar light is promising for terrestrial outdoor applications. However, its use in underground structures and/or microgravity environments (e.g., extraterrestrial structures) is forbidden. In these cases, there are issues related to the energy emitted from the indoor lighting system because it is not high enough to promote the photocatalytic mechanism. Moreover, microgravity does not allow the recovery of the photocatalytic slurry from the depolluted solution. In this work, the synthesis of a filmable nanocomposite based on semiconductor nanoparticles supported by photosensitized copolyacrylates was performed through a bulk in situ radical copolymerization involving a photosensitizer macromonomer. The macromonomer and the nanocomposites were characterized through UV-Vis, fluorescence and NMR spectroscopies, gel permeation chromatography and thermogravimetric analysis. The photocatalytic activity of the sensitized nanoc...
In this study, graphene oxide (GO) and reduced-thiolated GO (rGOSH) were used as 2D substrate to ... more In this study, graphene oxide (GO) and reduced-thiolated GO (rGOSH) were used as 2D substrate to fabricate nanocomposites with nanoparticles of gold nanospheres (AuNS) or nanorods (AuNR), via in situ reduction of the metal salt precursor and seed-mediated growth processes. The plasmonic sensing capability of the gold-decorated nanosheets were scrutinized by UV-visible (UV-VIS) spectroscopy. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analyses (TGA), and atomic force microscopy (AFM) were performed in order to prove the actual reduction that occurred concomitantly with the thiolation of GO, the increase in the hydrophobic character as well as the size, and preferential gathering of the gold nanoparticles onto the nanosheet substrates, respectively. Moreover, the theoretical electronic and infrared absorption (UV-VIS and IR) spectra were calculated within a time-dependent approach of density functional theory (DFT). Eventually, in...
Photocatalytic remediation represents a potential sustainable solution to the abatement of xenobi... more Photocatalytic remediation represents a potential sustainable solution to the abatement of xenobiotic pollutants released within the water environment. Aeroxide® P25 titanium dioxide nanoparticles (TiO2 NPs) are well-known as one of the most efficient photocatalysts in several applications, and have also been investigated in water remediation as suspended powder. Recently, their application in the form of thin films has been revealed as a potential alternative to avoid time-consuming filtration processes. Polymers represent suitable substrates to immobilize TiO2 NPs, allowing further production of thin films that can be exploited as a photoactive coating for environmental remediation. Nevertheless, the methods adopted to immobilize TiO2 NPs on polymer matrix involve time-consuming procedures and the use of several reactants. Here, titanium dioxide-based nanocomposites (NCx) were obtained through a new approach based on Methyl Methacrylate in situ bulk polymerization and were compare...
This review arises from the need to rationalize the huge amount of information on the structural ... more This review arises from the need to rationalize the huge amount of information on the structural and spectroscopic properties of a peculiar class of porphyrin derivatives—the non-ionic PEGylated porphyrins—collected during almost two decades of research. The lack of charged groups in the molecular architecture of these porphyrin derivatives is the leitmotif of the work and plays an outstanding role in highlighting those interactions between porphyrins, or between porphyrins and target molecules (e.g., hydrophobic-, hydrogen bond related-, and coordination-interactions, to name just a few) that are often masked by stronger electrostatic contributions. In addition, it is exactly these weaker interactions between porphyrins that make the aggregated forms more prone to couple efficiently with external perturbative fields like weak hydrodynamic vortexes or temperature gradients. In the absence of charge, solubility in water is very often achieved by covalent functionalization of the porphyrin ring with polyethylene glycol chains. Various modifications, including of chain length or the number of chains, the presence of a metal atom in the porphyrin core, or having two or more porphyrin rings in the molecular architecture, result in a wide range of properties. These encompass self-assembly with different aggregate morphology, molecular recognition of biomolecules, and different photophysical responses, which can be translated into numerous promising applications in the sensing and biomedical field, based on turn-on/turn-off fluorescence and on photogeneration of radical species.
The Spontaneous Symmetry Breaking (SSB) phenomenon is a natural event in which a system changes i... more The Spontaneous Symmetry Breaking (SSB) phenomenon is a natural event in which a system changes its symmetric state, apparently reasonless, in an asymmetrical one. Nevertheless, this occurrence could be hiding unknown inductive forces. An intriguing investigation pathway uses supramolecular aggregates of suitable achiral porphyrins, useful to mimic the natural light-harvesting systems (as chlorophyll). Using as SSB probe supramolecular aggregates of 5,10,15,20-tetrakis[p(ω-methoxypolyethyleneoxy)phenyl]porphyrin (StarP), a non-ionic achiral PEGylated porphyrin, we explore here its interaction with weak asymmetric thermal gradients fields. The cross-correlation of the experimental data (circular dichroism, confocal microscopy, atomic force microscopy, and cryo-transmission electron microscopy) revealed that the used building blocks aggregate spontaneously, organizing in flag-like structures whose thermally-induced circular dichroism depends on their features. Finally, thermal gradien...
Silver nanoparticles (AgNPs) stand out over other metal nanoparticles thanks to their peculiar ba... more Silver nanoparticles (AgNPs) stand out over other metal nanoparticles thanks to their peculiar bactericidal and spectroscopic properties. Tunability of the AgNPs chemical–physical properties could be provided through their organic covalent coating. On the other hand, PEGylated porphyrin derivatives are versatile heteromacrocycles investigated for uses in the biomedical field as cytotoxic and tracking agents, but also as sensors. In this work, an easy multi-step approach was employed to produce coated silver nanoparticles. Specifically, the AgNPs were functionalized with 5,10,15-[p-(ω-methoxy-polyethyleneoxy)phenyl]-20-(p-hydroxyphenyl)-porphyrin (P(PEG350)3), using chloropropanethiol as a coupling agent. The P(PEG350)3 was structurally characterized through MALDI-TOF mass spectrometry, NMR spectroscopy and thermal analyses. The functionalization of AgNPs was monitored step-by-step employing UV-Vis spectroscopy, dynamic light scattering and thermogravimetric techniques. HRTEM and STE...
An effective and convenient protocol for the synthesis of 1-substituted uracil-6-carbaldehyde der... more An effective and convenient protocol for the synthesis of 1-substituted uracil-6-carbaldehyde derivatives has been developed. A three-step sequence permits the preparation of uracil-6-carbaldehydes with various substituents at the N-1 in large quantities by using low-cost precursors. The aldehyde-functionalized uracils served as useful precursors for the preparation of meso-(1-substituted 6-uracil)-derivatives of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY). In this way, regioselectively functionalized BODIPYs with a direct connection to a nucleobase were prepared in yields of 30–45%. MALDI-TOF mass spectrometry, NMR, UV/vis absorption, and steady-state and time-resolved fluorescence spectroscopies were used to characterize the structures and the spectroscopic/photophysical properties of the resultant dyes.
Nanocomposites obtained by the decoration of graphene-based materials with silver nanoparticles (... more Nanocomposites obtained by the decoration of graphene-based materials with silver nanoparticles (AgNPs) have received increasing attention owing to their antimicrobial activity. However, the complex synthetic methods for their preparation have limited practical applications. This study aims to synthesize novel NanoHybrid Systems based on graphene, polymer, and AgNPs (namely, NanoHy-GPS) through an easy microwave irradiation approach free of reductants and surfactants. The polymer plays a crucial role, as it assures the coating layer/substrate compatibility making the platform easily adaptable for a specific substrate. AgNPs’ loading (from 5% to 87%) can be tuned by the amount of Silver salt used during the microwave-assisted reaction, obtaining spherical AgNPs with average sizes of 5–12 nm homogeneously distributed on a polymer-graphene nanosystem. Interestingly, microwave irradiation partially restored the graphene sp2 network without damage of ester bonds. The structure, morpholog...
The decontamination of water containing toxic metals is a challenging problem, and in the last ye... more The decontamination of water containing toxic metals is a challenging problem, and in the last years many efforts have been undertaken to discover efficient, cost-effective, robust, and handy technology for the decontamination of downstream water without endangering human health. According to the World Health Organization (WHO), 180 million people in the world have been exposed to toxic levels of arsenic from potable water. To date, a variety of techniques has been developed to maintain the arsenic concentration in potable water below the limit recommended by WHO (10 μg/L). Recently, a series of technological advancements in water remediation has been obtained from the rapid development of nanotechnology-based strategies that provide a remarkable control over nanoparticle design, allowing the tailoring of their properties toward specific applications. Among the plethora of nanomaterials and nanostructures proposed in the remediation field, graphene-based materials (G), due to their ...
A recent approach in the treatment of diseased cells/tissues is the use of smart, stimuli-respons... more A recent approach in the treatment of diseased cells/tissues is the use of smart, stimuli-responsive nanomaterials. Well-known examples include photosensitizer agents that after light irradiation at a specific wavelength generate singlet oxygen species (strongly cytotoxic) or self-assembled supramolecular structures, which blow up cancer cells by releasing their payload upon an external stimulus, thus making cancer cells swell and burst (so-called “nanobombs”). In this work we synthesized and characterized a polymeric star-like pentaporphyrin system (5P) that, depending on the photoexcitation wavelength selected, can act either as a photosensitizer or as a nanobomb. The 5P compound was characterized by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, nuclear magnetic resonance, UV–vis, and fluorescence spectroscopy techniques. The hydrodynamic size of the 5P compound in physiological buffer solution, as determined by dynamic light spectroscopy, pointed to the formation o...
The main objective of supramolecular chemistry is to mimic the macrosystems present in nature, a ... more The main objective of supramolecular chemistry is to mimic the macrosystems present in nature, a goal that fits perfectly with the green chemistry guidelines.
Abstract The measure of the acid concentration in an organic media is a common issue in chemistry... more Abstract The measure of the acid concentration in an organic media is a common issue in chemistry. With the aim to overcome this problem in a facile and inexpensive way, the spectroscopic properties of a PEGylate porphyrin derivative, the 5,10,15,20-p-(ω-methoxypolyethyleneoxyphenyl) porphyrin (P), as an acidity sensor were tested. Its behaviour was analysed in toluene and several fuels through acid titration experiments. In each case, examining UV–vis and fluorescence spectroscopic data, the disappearance of the free-base porphyrin derivative Uv–vis signals (B- and Q-bands) and the increasing of new bands, as a consequence of the added acid, was monitored. On the basis of these data it was possible to evaluate the presence of acid in several organic media as toluene, gasoline, diesel, and jet fuel, using our porphyrin derivative in very low amount (about 3 ppm). Finally, in order to exclude the risk of a negative contribution of P in ash formation, the complete oxidation of the porphyrin compound under common engine's combustion conditions was also ascertained.
Abstract An innovative solvent- and catalyst-free procedure for the grafting of acetylene groups ... more Abstract An innovative solvent- and catalyst-free procedure for the grafting of acetylene groups on polylactic acid (PLA) backbone is reported, using propargylamine as alkyne donor. The synthetic protocol was tested at different PLA/propargylamine molar ratio and the efficiency was determined in terms of functionalization degree and molecular weights. The engineering of PLA by the green protocol introduces alkyne moieties and generates free hydroxyl groups that are exploited to increase the alkyne functionality by treatment with pent-4-ynoic anhydride. Alkyne-grafted PLA derivatives are useful building blocks for access to a variety of functionalized polymers by Cu(I)-catalyzed cycloaddition reaction (CuAAC) with azides derivatives. As a proof of principle, methoxypolyethylene glycol azide and azide-fluor 545 are selected as models of hydrophilic polymer and fluorescent probe, respectively.
Colloids and Surfaces A: Physicochemical and Engineering Aspects
Abstract Hybrid gold nanoparticles covalently coated with 5,10,15-p-(ω-methoxy polyethyleneoxyphe... more Abstract Hybrid gold nanoparticles covalently coated with 5,10,15-p-(ω-methoxy polyethyleneoxyphenyl)-20-p-(hydroxyphenyl) porphyrin molecules, having about 16 repetitive units in each of its poly(oxyethylene) branches, were synthesized and characterized by UV–vis, fluorescence, dynamic light scattering (DLS), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) measurements. Their [H3O+] optical sensing behavior was also studied and compared to that of the similar water-soluble star polymer 5,10,15,20-tetrakis p-[ω-methoxypoly(ethyleneoxy)]phenylporphyrin. Changing the pH of a solution, the UV–vis spectra of the PEGylate porphyrin gold nanoparticles conjugates showed the gradual disappearance of the Soret band at 424 nm and the progressive increase of a new band at 451 nm. Upon acidic titration, also the fluorescence spectra showed a gradual disappearing of the fluorescence at 654 nm. Moreover, an unusual B-Band red-shift and a decreasing of porphyrin core basicity were observed for this porphyrin bonded to the gold nanoparticle surfaces. To rationalize these phenomena an in silico TD-DFT calculation study was then conducted. For its properties, this new system: can be used in both aqueous and organic media; by a simple treatment of the solution at 80 °C under N2 gas stream the starting Soret signals can be recovered; the nanoparticles can be eventually removed from the solution by centrifugation.
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Papers by Angelo Nicosia