Marco d'Ischia

• chemistry
• Professor (Full) at University of Naples Federico II

Herein is delineated a first systematic framework for the definition of structure‐antioxidant property relationships in the dihydroxynaphthalene (DHN) series. The results obtained by a combined experimental and theoretical approach revealed that 1,8‐DHN is the best performing antioxidant platform, with its unique hydrogen‐bonded peri‐hydroxylation...

The design of modern devices that can fulfil the requirements for sustainability and renewable energy applications calls for both new materials and a better understanding of the mixing of existing materials. Among those, surely organic–inorganic hybrids are gaining increasing attention due to the wide possibility to tailor their properties by accur...

Hypothesis The possibility to use hexamethylenediamine (HMDA) to impart film forming ability to natural polymers including eumelanins and plant polyphenols endowed with biological activity and functional properties has been recently explored with the aim to broaden the potential of polydopamine (PDA)-based films overcoming their inherent limitation...

The addition of thiol compounds to o-quinones, as exemplified by the biologically relevant conjugation of cysteine to dopaquinone, displays an anomalous 1,6-type regiochemistry compared to the usual 1,4-nucleophilic addition, for example, by amines, which has so far eluded intensive investigations. By means of an integrated experimental and computa...

The deposition efficiency and the electrochemical properties, as well as the thickness and hydrophilicity, of the coatings obtained from catechol (1,2-benzenediol), resorcinol (1,3-benzenediol) and hydroquinone (1,4-benzenediol) at pH 5.0 have been compared with the aid of cyclic voltammetry, chronoamperometry and electrochemical impedance spectra...

Δ2,2’-bi-(2H-1,4-benzothiazine) chromophore of trichochrome pigments occurring in red hair and feathers has been recognized as a source of inspiration for the design of functional chromophores given its excellent photochromic, solvatochromic, and acidichromic properties. Here we report the synthesis of a symmetric homolog of the bibenzothiazine sys...

Reported herein is the purification of the pigment of black sturgeon caviar and its unambiguous identification as a typical eumelanin by means of chemical degradation coupled with electron paramagnetic resonance (EPR) evidence. HPLC and LC-MS analysis of oxidative degradation mixtures revealed the formation of pyrrole-2,3,5-tricarboxylic acid (PTCA...

Halloysite nanotubes (HNTs) represent a versatile core structure for the design of functional nanosystems of biomedical interest. However, the development of selective methodologies for the site-controlled functionalization of the nanotubes at specific sites is not an easy task. This study aims to accomplish a procedure for the site-selective/speci...

Cation-π interactions between ammonium and catechol groups provide a commonly held paradigm in the complex interplay of noncovalent forces that govern both biological phenomena, such as underwater adhesion in mussel byssus and other marine organisms, and aggregation processes in self-assembly of catecholamine-derived polymers. However, closer consi...

A concise highlight of the main types of chromophoric systems obtained in the authors’ and other laboratories through biomimetic chemistry or synthetic manipulation of nature‐inspired o‐quinones is the primary focus of this Minireview. Following oxidative conversion of a variety of natural catechol substrates like DOPA, dopamine, 5‐S‐cysteinyldopa...

An interdisciplinary review of the chemical literature that points to a unifying scenario for the origin of life, referred to as the Primordial Multifunctional organic Entity (PriME) scenario, is provided herein. In the PriME scenario it is suggested that the Insoluble Organic Matter (IOM) in carbonaceous chondrites, as well as interplanetary dust...

Polydopamine (PDA) films allow to functionalize almost all materials with a conformal and chemically active coating. These coatings can react with reducible metallic cations and with all kinds of molecules carrying nucleophilic groups. Recently, our team extended PDA chemistry to a vast repertoire of oxidants and to acidic conditions. However, the...

Chiral porphyrin hetero-aggregates, produced from meso-tetrakis(4-N-methylpyridyl) porphyrin H2T4 and copper(II) meso-tetrakis(4-sulfonatophenyl)porphyrin CuTPPS by an imprinting effect in the presence of L-3,4-dihydroxyphenylalanine (L-DOPA), are shown herein to serve as templates for the generation of chiral structures during the oxidative conver...

The interaction potential energy surfaces (IPESs) of four alkaline metal cations (Na⁺, K⁺, Rb⁺ and Cs⁺) complexed with phenol and catechol were explored by accurate ab initio calculations to investigate the interplay of different noncovalent interactions and their behavior along the alkali metal series and upon –OH substitution. Selected one-dimens...

Phenolic polymers produced by enzymatic oxidation under biomimetic and eco-friendly reaction conditions are usually endowed with potent antioxidant properties. These properties, coupled with the higher biocompatibility, stability and processability compared to low-molecular weight phenolic compounds, open important perspectives for various applicat...

Tannins have always been the subject of great interest for their countless properties, first of all their ability to produce functional coatings on a variety of materials. We report herein a comparative evaluation of the antioxidant properties of wood tannin-based coated substrates. In particular, nylon membrane filters were functionalized with che...

The mechanism of the acid-dependent interring dehydrogenation in the conversion of the single-bonded 3-phenyl-2H-1,4-benzothiazine dimer 2 to the Δ2,2'-bi(2H-1,4-benzothiazine) scaffold of red hair pigments is disclosed herein. Integrated chemical oxidation and oxygen consumption experiments, coupled with electron paramagnetic resonance (EPR) analy...

A new red hair-inspired 1,4-benzothiazine-based scaffold is disclosed herein, built upon a modular D-π-A architecture via condensation of the easily accessible 3-phenyl-2H-1,4-benzothiazine with indole-3-carboxaldehyde. The compound was obtained in around 50% yields and was characterized by complete spectroscopic analysis. The new benzothiazine-bas...

Melanins are a group of dark insoluble pigments found widespread in nature. In mammals, the brown-black eumelanins and the reddish-yellow pheomelanins are the main determinants of skin, hair, and eye pigmentation and play a significant role in photoprotection as well as in many biological functions ensuring homeostasis. Due to their broad-spectrum...

The tyrosinase-catalyzed oxidation of tyramine, leading to the deposition of pseudo-polydopamine (ψ-PDA) thin films, is disclosed herein as a superior technology for surface functionalization and coating at a neutral pH and at a low substrate concentration, compared to the standard autoxidative PDA coating protocols. Smooth ψ-PDA thin films of vari...

Disclosed herein is the first experimental evidence for a direct correlation between the broadband visible light absorption (“blackness”) and the coexistence of reduced and oxidized substructures in a set of model polymers from isomeric dihydroxynaphthalenes structurally related to fungal melanin (mycomelanin) from 1,8-dihydroxynaphthalene. Excelle...

Bioconjugation of a recently developed photoacoustic nanoprobe, based on silica-templated eumelanin-silver hybrid nanoparticles (MelaSil_Ag-NPs), with human serum albumin (HSA) is disclosed herein as an efficient and practical strategy to improve photostability and to perform SPARC mediated internalization in breast cancer cells. Modification of NP...

Largely produced agri-food byproducts represent a sustainable and easily available source of phenolic compounds, such as lignins and tannins, endowed with potent antioxidant properties. We report herein the characterization of the antioxidant properties of nine plant-derived byproducts. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antio...

Green and alternative strategies for the preparation of silver nanoparticles (AgNP) are the focus of considerable attention, given their wide range of applications. A clean, eco-friendly, low-cost, scalable and straightforward protocol for the production of AgNP is reported, using hydrolyzed spent coffee grounds (HSCG) both as a reducing agent and...

The fungal pathways of melanin synthesis have so far been little considered as a source of bio-inspiration in the field of functional materials, despite the interesting properties exhibited by Ascomyces melanins from 1,8-dihydroxynaphthalene (1,8-DHN), including the ability to shield organisms from ionizing radiation. Herein is reported for the fir...

The reliability of several DFT functionals and of the Möller-Plesset Second Order Perturbation Theory Calculations with Modified Basis Sets (MP2mod) approach in describing cation-π interactions is systematically investigated by benchmarking their performances with respect to high quality reference CCSD(T) calculations of the binding energies betwee...

This Chapter highlights the most significant applications of pyrroles, indoles, carbazoles and related heterocycles for the period 2009-October 2019. A prominent position is occupied by polymers based on these heterocycles. The number of papers addressing conductive polypyrroles in the last 10 years is more than doubled as compared to the previous...

Melanins, a group of dark insoluble pigments found widespread in nature, have become the focus of growing interest in materials science for various biomedical and technological applications, including opto‐bioelectronics, nanomedicine and mussel‐inspired surface coating. Recent progress in the understanding of melanin optical, paramagnetic redox, a...

Melanins, a group of dark insoluble pigments found widespread in nature, have become the focus of growing interest in materials science for various biomedical and technological applications, including opto‐bioelectronics, nanomedicine and mussel‐inspired surface coating. Recent progress in the understanding of melanin optical, paramagnetic redox an...

Self-patterning processes originated by physical stimuli have been extensively documented in thin films, whereas spontaneous wrinkling phenomena due to chemical transformation processes are, to the best of our knowledge, unprecedented. Herein we report a case of spontaneous polymerization-driven surface nano-patterning ( 500 nm) that develops in s...

The reaction-based deposition on various surfaces of an all-organic fluorescent coating is reported here, involving autoxidation of 2 mM dopamine in carbonate buffer at pH 9.0, in the presence of a 1 mM diamine–resorcinol coupler (Bis–Res) prepared from 2,4-dihydroxybenzaldehyde and hexamethylenediamine (HMDA). Spectral analysis of the films couple...

Astrochemistry and astrobiology, the fascinating disciplines that strive to unravel the origin of life, have opened unprecedented and unpredicted vistas into exotic compounds as well as extreme or complex reaction conditions of potential relevance for a broad variety of applications. Representative, and so far little explored sources of inspiration...

In the last few years, the development of versatile coating chemistries has become a hot topic in surface science after the discovery that catecholamines can lead to conformal coatings upon oxidation from aqueous solutions. Recently, it was found that aminomalononitrile (AMN), a molecule implicated in the appearance of life on earth, is an excellen...

Hexamethylenediamine (HMDA) and other long chain aliphatic diamines can induce substrate-independent polymer film deposition from dopamine and several other catechols substrates at relatively low concentrations, however the mechanism of the diamine-promoted effect has remained little understood. Herein, we report data indicating that: (a) film depo...

Developing effective strategies to increase the chemical stability and to fine‐tune the physico‐chemical properties of melanin biopolymers by rational control of π‐electron conjugation is an important goal in materials science for biomedical and technological applications. Herein we report that poly‐1,8‐dihydroxynaphthalene (pDHN), a non‐nitrogenou...

Nanoscale disassembly of mussel-inspired polydopamine (PDA) in ionicliquids (ILs) was recently shown to induce an electron paramagnetic resonance (EPR)-detectable reorganization of free radical centers in the resulting nanoparticles (NPs) in an IL-controlled manner. Herein, we report electrical impedance spectroscopy (EIS) data showing that PDA NPs...

Developing safe and high efficiency contrast tools is an urgent need to allow in vivo applications of photoacoustics (PA), an emerging biomolecular imaging methodology, with poor invasiveness, deep penetration, high spatial resolution and excellent endogenous contrast. Eumelanins hold huge promise as biocompatible, endogenous photoacoustic contrast...

The authors regret that few mistakes were made in the original publication by Mrówczyński et al.[...]

Reported herein is a unimolecular variant of the fluorescence turn-on oxidative coupling of catecholamines with resorcinols ("FluoResCat") based on the easily accessible conjugate 4-(2-((2,4-dihydroxybenzyl)amino)ethyl)benzene-1,2-diol (1). The process involves an alkali-activatable sequence of autoxidation and intramolecular cyclization steps with...

The NanoTech Poland is an annual international conference with a strong scientific agenda focused on nanotechnology in energy, environment, and biomedicine. The Nanotech Poland 2018 was held at the NanoBioMedical Centre and Department of Physics at Adam Mickiewicz University in Poznań from June 6th to June 9th. The aim of NanoTech Poland 2018 was t...

The organic/inorganic interface in thin nanosized porous structure has a key role in determining the final properties of the composite materials. By using the porous silicon/eumelanin hybrids as a case study, the role of this interface was investigated by experimental and computational methods. Our results show that an increased polymer density clo...

Despite extensive investigations over the past decade, the chemical basis of the extraordinary underwater adhesion properties of polydopamine (PDA) has remained not entirely understood. The bulk of evidence points to PDA wet adhesion as a complex process based on film deposition, and growth in which primary amine groups, besides catechol moieties,...

Oxygenated derivatives of polycyclic aromatic hydrocarbons (PAHs), or oxyPAHs, recently captured the interest of the scientific community for their photochemical reactivity in a water ice matrix mimicking the interstellar medium. Furthermore, oxyPAHs are interesting molecules for the study of the origin of life for their prebiotic potential. Howeve...

Excellent and selective correlations between the electron-transfer (ET) or hydrogen atom transfer (HAT) capacity (DPPH and lipid peroxidation inhibition assays) and EPR indices of π-electron spin delocalization delineate specific structural...

1,8-Naphthalenediol (dihydroxynaphthalene, 1,8-DHN) has been shown to be a potent hydrogen atom transfer (HAT) antioxidant compound because of the strong stabilization of the resulting free radical by intramolecular hydrogen bonding. However, the properties, reactivity, and fate of the 1,8-DHN phenoxyl radical have remained so far uncharted. Herein...

To inquire into the role of the carboxyl group as determinant of the properties of 5,6-dihydroxyindole melanins, melanins from aerial oxidation of 5,6-dihydroxyindole (DHICA) and its methyl ester MeDHICA were comparatively tested for their antioxidant activity. MALDI MS spectrometry analysis of MeDHICA melanin provided evidence for a collection of...

Melanin biopolymers are currently the focus of growing interest for a broad range of applications at the cutting edge of biomedical research and technology. This Special Issue presents a collection of papers dealing with melanin-type materials, e.g., polydopamine, for classic and innovative applications, offering a stimulating perspective of curren...

Catechols are widely found in nature taking part in a variety of biological functions, ranging from the aqueous adhesion of marine organisms to the storage of transition metal ions [...]

The origin of eumelanin optical properties remains a formidable conundrum preventing a detailed understanding of the complex photo-protective role of these widespread natural pigments and the rational design of innovative bioinspired materials for optoelectronic applications. Here we report the unusual kinetic and thickness-dependent evolution of t...

A detailed computational investigation of the 5,6-dihydroxyindole (DHI)-based porphyrin-type tetramer first described by Kaxiras as a theoretical structural model for eumelanin biopolymers is reported herein, with a view to predicting the technological potential of this unique bioinspired tetracatechol system. All possible tautomers/conformers, as...

The oxidative polymerization of 5,6-dihydroxybenzothiophene (DHBT), the sulfur analog of the key eumelanin building block 5,6-dihydroxyindole (DHI), was investigated to probe the role of nitrogen in eumelanin build-up and properties. Unlike DHI, which gives a typical black insoluble eumelanin polymer on oxidation, DHBT is converted to a grayish amo...

We disclose herein the first example of stable monodispersed hybrid nanoparticles (termed MelaSil-NPs) made up of eumelanin biopolymer intimately integrated into a silica nanoscaffold matrix and endowed with high antioxidant and cytoprotective effects associated with a specific subcellular localization. MelaSil-NPs have been fabricated by an optimi...

The role of 5,6-dihydroxyindole (DHI)-based oligomers, including porphyrin-like tetramers, in polydopamine (PDA) film formation was addressed by a comparative structural investigation against model polymers from DHI and its 2,7’-dimer. MALDI-MS data showed that: a) PDA is structurally different from DHI melanin and does not contain species compatib...

The deposition of polydopamine (PDA) films on surfaces, a versatile deposition method with respect to the nature of the used substrate, is unfortunately accompanied by deposition of insoluble precipitates in solution after a prolonged oxidation time of dopamine solutions. Therefore, there is evident interest to find methods able to stop the deposit...

Conjugation of naturally occurring catecholic compounds with thiols is a versatile and facile entry to a broad range of bioinspired multifunctional compounds for diverse applications in biomedicine and materials science. We report herein the inhibition properties of the caffeic acid- dihydrolipoic acid S-conjugate, 2-S-lipoylcaffeic acid (LC), on m...

Porous Si/eumelanin hybrids are a novel class of organic–inorganic hybrid materials that hold considerable promise for photovoltaic applications. Current progress toward device setup is, however, hindered by photocurrent stability issues, which require a detailed understanding of the mechanisms underlying the buildup and consolidation of the eumela...

Spent coffee grounds are a by-product with a large production all over the world. The aim of this study was to explore the effects of a simulated digestion-fermentation treatment on hydrolyzed spent coffee grounds (HSCG) and to investigate the antioxidant properties of the digestion and fermentation products in human hepatocellular carcinoma HepG2...

Tyrosine-containing tripeptides form eumelanin-like pigments with tunable properties

The occasional greening of sweet potatoes and other plant tissues observed during cooking or other food processing has been shown to arise from the autoxidative coupling of chlorogenic acid (CGA, 5-caffeoylquinic acid) with amino acid components leading to trihydroxybenzacridine pigments. To explore the potential of this reaction for food coloring,...

Intrigued by the emerging biomedical relevance and technological potential of fungal melanins, and prompted by the virtual lack of information about their structural arrangement, we report herein an optimized synthetic protocol for a potential structural model of Ascomyces allomelanin via enzyme-catalyzed oxidative polymerization of 1,8-dihydroxyna...

Although it has long been known that the peculiar electronic-ionic conductor behavior of eumelanin is critically dependent on hydration, the detailed mechanisms by which water-polymer interactions control and affect the conduction properties have remained largely obscure. In this paper, we report a remarkable anisotropy and giant polarization effec...

Skin photoprotection is commonly believed to rely on the photochemistry of 5,6-dihydroxyindole (DHI)- and 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-based eumelanin building blocks. Attempts to elucidate the underlying excited-state relaxation mechanisms have been partly unsuccessful due to the marked instability to oxidation. Herein, we report...

The exploitation of easily accessible and non-toxic natural catechol compounds for surface functionalization and coating is attracting growing interest for biomedical applications. We report herein the deposition on different sub-strates of chemically stable thin films by autoxidation of 1 mM caffeic acid (CA) solutions at pH 9 in the presence of e...

Eumelanins, the chief photoprotective pigments in man and mammals, owe their black color to an unusual broadband absorption spectrum whose origin is still a conundrum. Excitonic effects from the interplay of geometric order and disorder in 5,6-dihydroxyindole (DHI)-based oligomeric/polymeric structures play a central role, however the contributions...

Despite the growing scientific and technological relevance of polydopamine (PDA), a eumelanin-like adhesive material widely used for surface functionalization and coating, knowledge of its structural and physicochemical properties, including in particular the origin of paramagnetic behavior, is still far from being complete. Herein, we disclose the...

Efficient surface functionalization with polydopamine films (PDA) can be easily achieved on virtually any object via single immersion in slightly basic dopamine solutions. In such conditions, however, poor homogeneity, low thickness and long time of reaction are usually the major limitations. Herein, we report a rational entry to the control of PDA...

Recent advances in the chemistry of melanins have begun to disclose a number of important structure-property-function relationships of crucial relevance to the biological role of human pigments, including skin (photo) protection and UV-susceptibility. Even slight variations in the monomer composition of black eumelanins and red pheomelanins have be...

Although epidemiological data would support a photoprotective role of melanin pigments in the skin, the detailed underlying mechanisms are still a matter of debate and some controversy. This confusion may derive in part from unreliable in vitro experiments and in part from the widespread, still largely unwarranted, assumption that melanin (eumelani...

Treatment with boiling 6 M HCl increases up to 30 times the intrinsic antioxidant potency of spent coffee grounds, leading to a versatile multifunctional material (hydrolyzed spent coffee grounds, HSCG). Spectral and morphological analysis suggest that the remarkable potentiation of the antioxidant activity is due to efficient removal of the hydrol...

Bioinspired aerogel functionalization by surface modification and coating is in high demand for biomedical and technological applications. In this paper, we report an expedient three-step entry to all-natural surface-functionalized nanostructured aerogels based on a) TEMPO/NaClO promoted synthesis of cellulose nanofibers (TOCNF); b) freeze-drying f...

We report herein a novel antioxidant biomaterial, named hydrolyzed spent coffee grounds (HSCG), from overnight treatment of spent coffee grounds (SCG) with 6 M HCl, at 100 °C.1 The biocompatibility and cytoprotection properties of HSCG were investigated in comparison with SCG on hepatocarcinoma (HepG2) cells. HSCG proved to be non-toxic at doses as...

Eumelanins, the black insoluble pigments of human skin, eyes and substantia nigra (neuromelanin), stand today as a unique source of inspiration for the design and implementation of soft biocompatible multifunctional materials for bio-optoelectronic devices. Interest in eumelanins stems from bioavailability, biocompatibility and a peculiar set of ph...

The curing time of an adhesive material is determined by the polymerization and crosslinking kinetics of the adhesive formulation and needs to be optimized for the particular application. Here, we explore the possibility of tuning the polymerization kinetics and final mechanical properties of tissue-adhesive PEG gels formed by polymerization of end...

During the past decade, melanins and melanogenesis have attracted growing interest for a broad range of biomedical and technological applications. The burst of polydopamine-based multifunctional coatings in materials science is just one example, and the list may be expanded to include melanin thin films for organic electronics and bioelectronics, d...

A relatively intense photocurrent density up to 3.8 mA/cm2 was induced by visible light in n+-doped porous silicon (n-PSi) coated with a eumelanin thin film produced by ammonia-induced solid state polymerization (AISSP) of 5,6-dihydroxyindole (DHI). The photocurrent was not affected by acetic acid vapors but was irreversibly abated by gaseous ammon...

The oxidative polymerization of 5,6-dihydroxyindoles and related hydroxyindoles at pH<3 is diverted from the usual eumelanin-forming pathway to produce mixtures of symmetric and asymmetric triazatruxenes (TATs), which could be separated and characterized for their opto-electronic properties with the aid of TD-DFT calculations. Data showed that the...

Invited for this month's cover is the group of Dr. Paola Manini from the University of Naples Federico II. The cover picture shows the concept underlying the design of a melanin-inspired electroluminescent material for OLED devices. This article is part of a well-structured research project aimed at imitating Nature's most enigmatic and fascinating...

Polycysteinyldopamine (pCDA), a red hair-inspired polydopamine-like polymer with ionic conductor behavior, can produce smooth and highly adhesive thin films and coatings on quartz, glass and other surfaces, and is shown to markedly accelerate the autoxidation of glutathione at physiological pH via an efficient redox exchange process.

The oxidative polymerization of 5,6-dihydroxyindoles and related hydroxyindoles at pH<3 is diverted from the usual eumelanin-forming pathway to produce mixtures of symmetric and asymmetric triazatruxenes (TATs), which could be separated and characterized for their opto-electronic properties with the aid of TD-DFT calculations. Data showed that the...

Over the past decade synthetic melanins, melanin-like polymers and melanin-based copolymers have been the focus of growing attention as soft biocompatible functional materials for engineering high performance, low cost optoelectronic devices, such as memory devices, light emitting diodes and field effect transistors. The unique combination of physi...

The structural modification of the resveratrol scaffold is currently an active issue in the quest for more potent and versatile antioxidant derivatives for biomedical applications. Disclosed herein is an expedient and efficient entry to a novel class of resveratrol derivatives featuring an unprecedented 2-phenylbenzoselenophene skeleton. The new co...

The commonly accepted definition of Fanconi anemia (FA) relying on DNA repair deficiency is submitted to a critical review starting from the early reports pointing to mitomycin C bioactivation and to the toxicity mechanisms of diepoxybutane and a group of nitrogen mustards causing DNA crosslinks in FA cells. A critical analysis of the literature pr...