Conjugation to gold nanoparticles of methionine gamma-lyase, a cancer-starving enzyme. Physicochemical characterization of the nanocomplex for prospective nanomedicine applications

The pyridoxal 5'-dependent enzyme methionine γ-lyase (MGL) catalyzes the degradation of methionine. This activity has been profitable to develop an antitumor agent exploiting the strict dependence of most malignant cells on the availability of methionine. Indeed, methionine depletion blocks tumor proliferation and leads to an increased susceptibility to anticancer drugs. Here, we explore the conjugation of MGL to gold nanoparticles capped with citrate (AuNPs) as a novel strategy to deliver MGL to cancer cells. Measurements of Transmission Electron Microscopy, Dynamic Light Scattering, Asymmetrical Flow Field-Flow Fractionation, X-ray Photoelectron Spectroscopy, and Circular Dichroism allowed to achieve an extensive biophysical and biochemical characterization of the MGL-AuNP complex including particle size, size distribution, MGL loading yield, enzymatic activity, and impact of gold surface on protein structure. Noticeably, we found that activity retention was improved over time for the enzyme adsorbed to AuNPs with respect to the enzyme free in solution. The acquired body of knowledge on the nanocomplex properties and this encouraging stabilizing effect upon conjugation are the necessary basis for further studies aimed at the evaluation of the therapeutic potential of MGL-AuNP complex in a biological milieu.

Raman spectroscopy and topological machine learning for cancer grading

In the last decade, Raman Spectroscopy is establishing itself as a highly promising technique for the classification of tumour tissues as it allows to obtain the biochemical maps of the tissues under investigation, making it possible to observe changes among different tissues in terms of biochemical constituents (proteins, lipid structures, DNA, vitamins, and so on). In this paper, we aim to show that techniques emerging from the cross-fertilization of persistent homology and machine learning can support the classification of Raman spectra extracted from cancerous tissues for tumour grading. In more detail, topological features of Raman spectra and machine learning classifiers are trained in combination as an automatic classification pipeline in order to select the best-performing pair. The case study is the grading of chondrosarcoma in four classes: cross and leave-one-patient-out validations have been used to assess the classification accuracy of the method. The binary classification achieves a validation accuracy of 81% and a test accuracy of 90%. Moreover, the test dataset has been collected at a different time and with different equipment. Such results are achieved by a support vector classifier trained with the Betti Curve representation of the topological features extracted from the Raman spectra, and are excellent compared with the existing literature. The added value of such results is that the model for the prediction of the chondrosarcoma grading could easily be implemented in clinical practice, possibly integrated into the acquisition system.

Quantum biology. π-π entanglement signatures in Protein-DNA interactions

DNA biological functions are carried out by individual proteins that interact with specific sequences along DNA to prime molecular processes required by cellular metabolism. Protein-DNA interactions include DNA replication, gene expression and its regulation, DNA repair, DNA restriction and modification by endonucleases, generally classified as enzymatic functions, or transcription factors functions. To find specific binding target sequences and finalize their activities, proteins must operate in symbiosis with cellular crowded environment identifying extremely small cognate sequences along the DNA chain, ranging from 15-20 bps for repressors to 4-6 bps for restriction enzymes in less than one second.

A Copper nanoparticles-based polymeric spray coating: Nanoshield against Sars-Cov-2

Face masks are an effective protection tool to prevent bacterial and viral transmission. However, commercial face masks contain filters made of materials that are not capable of inactivating either SARS-CoV-2. In this regard, we report the development of an antiviral coating of polyurethane and Copper nanoparticles on a face mask filter fabricated with a spray technology that is capable of inactivating more than 99% of SARS-CoV-2 particles in 30 min of contact.

Exploiting gold nanoparticles for diagnosis and cancer treatments

Gold nanoparticles (AuNPs) represent a relatively simple nanosystem to be synthesised and functionalized. AuNPs offer numerous advantages over different nanomaterials, primarily due to highly optimized protocols for their production with sizes in the range 1-150 nm and shapes, spherical, nanorods (AuNRs), nanocages, nanostars or nanoshells (AuNSs), just to name a few. AuNPs possess unique properties both from the optical and chemical point of view. AuNPs can absorb and scatter light with remarkable efficiency. Their outstanding interaction with light is due to the conduction electrons on the metal surface undergoing a collective oscillation when they are excited by light at specific wavelengths. This oscillation, known as a localized surface plasmon resonance, causes the absorption and scattering intensities of AuNPs to be significantly higher than identically sized non-plasmonic nanoparticles. In addition, AuNP absorption and scattering properties can be tuned by controlling the particle size, shape, and the local refractive index near the particle surface. By the chemical side, AuNPs offer the advantage of functionalization with therapeutic agents through covalent and ionic binding, which can be useful for biomedical applications, with particular emphasis on cancer treatments. Functionalized AuNPs exhibit good biocompatibility and controllable distribution patterns when delivered in cells and tissues, which make them particularly fine candidates for the basis of innovative therapies. Currently, major available AuNP-based cancer therapeutic approaches are the photothermal therapy (PTT) or photodynamic therapy (PDT). PTT and PDT rely upon irradiation of surface plasmon resonant AuNPs (previously delivered in cancer cells) by light, in particular, in the near-infrared range. Under irradiation, AuNPs surface electrons are excited and resonate intensely, and fast conversion of light into heat takes place in about 1 ps. The cancer cells are destroyed by the induced hyperthermia, i.e. the condition under which cells are subject to temperature in the range of 41 °C-47 °C for tens of minutes. The review is focused on the description of the optical and thermal properties of AuNPs that underlie their continuous and progressive exploitation for diagnosis and cancer therapy.

Protein-DNA target search relies on quantum walk

Protein-DNA interactions play a fundamental role in all life systems. A critical issue of such interactions is given by the strategy of protein search for specific targets on DNA. The mechanisms by which the protein are able to find relatively small cognate sequences, typically 15-20 base pairs (bps) for repressors, and 4-6 bps for restriction enzymes among the millions of bp of non-specific chromosomal DNA have hardly engaged researchers for decades. Recent experimental studies have generated new insights on the basic processes of protein-DNA interactions evidencing the underlying complex dynamic phenomena involved, which combine three-dimensional and one-dimensional motion along the DNA chain. It has been demonstrated that protein molecules have an extraordinary ability to find the target very quickly on the DNA chain, in some cases, with two orders of magnitude faster than the diffusion limit. This unique property of protein-DNA search mechanism is known as facilitated diffusion. Several theoretical mechanisms have been suggested to describe the origin of facilitated diffusion. However, none of such models currently has the ability to fully describe the protein search strategy. In this paper, we suggest that the ability of proteins to identify consensus sequences on DNA is based on the entanglement of π-π electrons between DNA nucleotides and protein amino acids. The π-π entanglement is based on Quantum Walk (QW), through Coin-position entanglement (CPE). First, the protein identifies a dimer belonging to the consensus sequence, and localize a π on such dimer, hence, the other π electron scans the DNA chain until the sequence is identified. Focusing on the example of recognition of consensus sequences of EcoRV or EcoRI, we will describe the quantum features of QW on protein-DNA complexes during the search strategy, such as walker quadratic spreading on a coherent superposition of different vertices and environment-supported long-time survival probability of the walker. We will employ both discrete- or continuous-time versions of QW. Biased and unbiased classical Random Walk (CRW) have been used for a long time to describe the Protein-DNA search strategy. QW, the quantum version of CRW, has been widely studied for its applications in quantum information applications. In our biological application, the walker (the protein) resides at a vertex in a graph (the DNA structural topology). Differently to CRW, where the walker moves randomly, the quantum walker can hop along the edges in the graph to reach other vertices entering coherently a superposition across different vertices spreading quadratically faster than CRW analogous evidencing the typical speed up features of the QW. When applied to a protein-DNA target search problem, QW gives the possibility to achieve the experimental diffusional motion of proteins over diffusion classical limits experienced along DNA chains exploiting quantum features such as CPE and long-time survival probability supported by the environment. In turn, we come to the conclusion that, under quantum picture, the protein search strategy does not distinguish between one-dimensional (1D) and three-dimensional (3D) cases.

Advanced Infrared Technology and Applications 2020: introduction to the feature issue

The 2020 edition of the Applied Optics (AO) special issue on advanced infrared technology and applications (AITA) collects significantly expanded refereed papers presented at the conference of the same name, held in Florence, Italy, 16-19 September 2019. All authors who participated at the conference were contacted and invited to contribute to this special issue. The issue also was expanded to include contributions from other practitioners of IR through direct contact and a call for papers published in AO.

Contribution of Raman Spectroscopy to Diagnosis and Grading of Chondrogenic Tumors

In the last decade, Raman Spectroscopy has demonstrated to be a label-free and non-destructive optical spectroscopy able to improve diagnostic accuracy in cancer diagnosis. This is because Raman spectroscopic measurements can reveal a deep molecular understanding of the biochemical changes in cancer tissues in comparison with non-cancer tissues. In this pilot study, we apply Raman spectroscopy imaging to the diagnosis and grading of chondrogenic tumors, including enchondroma and chondrosarcomas of increasing histologic grades. The investigation included the analysis of areas of 50×50 μm² to approximately 200×200 μm², respectively. Multivariate statistical analysis, based on unsupervised (Principal Analysis Components) and supervised (Linear Discriminant Analysis) methods, differentiated between the various tumor samples, between cells and extracellular matrix, and between collagen and non-collagenous components. The results dealt out basic biochemical information on tumor progression giving the possibility to grade with certainty the malignant cartilaginous tumors under investigation. The basic processes revealed by Raman Spectroscopy are the progressive degrading of collagen type-II components, the formation of calcifications and the cell proliferation in tissues ranging from enchondroma to chondrosarcomas. This study highlights that Raman spectroscopy is particularly effective when cartilaginous tumors need to be subjected to histopathological analysis.

An E-Nose for the Monitoring of Severe Liver Impairment: A Preliminary Study

Biologically inspired to mammalian olfactory system, electronic noses became popular during the last three decades. In literature, as well as in daily practice, a wide range of applications are reported. Nevertheless, the most pioneering one has been (and still is) the assessment of the human breath composition. In this study, we used a prototype of electronic nose, called Wize Sniffer (WS) and based it on an array of semiconductor gas sensor, to detect ammonia in the breath of patients suffering from severe liver impairment. In the setting of severely impaired liver, toxic substances, such as ammonia, accumulate in the systemic circulation and in the brain. This may result in Hepatic Encephalopathy (HE), a spectrum of neuro-psychiatric abnormalities which include changes in cognitive functions, consciousness, and behaviour. HE can be detected only by specific but time-consuming and burdensome examinations, such as blood ammonia levels assessment and neuro-psychological tests. In the presented proof-of-concept study, we aimed at investigating the possibility of discriminating the severity degree of liver impairment on the basis of the detected breath ammonia, in view of the detection of HE at its early stage.

In Situ Surface-Enhanced Raman Spectroscopy of Cellular Components: Theory and Experimental Results

In the last decade, surface-enhanced Raman spectroscopy (SERS) met increasing interest in the detection of chemical and biological agents due to its rapid performance and ultra-sensitive features. Being SERS a combination of Raman spectroscopy and nanotechnology, it includes the advantages of Raman spectroscopy, providing rapid spectra collection, small sample sizes, characteristic spectral fingerprints for specific analytes. In addition, SERS overcomes low sensitivity or fluorescence interference that represents two major drawbacks of traditional Raman spectroscopy. Nanoscale roughened metal surfaces tremendously enhance the weak Raman signal due to electromagnetic field enhancement generated by localized surface plasmon resonances. In this paper, we detected label-free SERS signals for arbitrarily configurations of dimers, trimers, etc., composed of gold nanoshells (AuNSs) and applied to the mapping of osteosarcoma intracellular components. The experimental results combined to a theoretical model computation of SERS signal of specific AuNSs configurations, based on open cavity plasmonics, give the possibility to quantify SERS enhancement for overcoming spectral fluctuations. The results show that the Raman signal is locally enhanced inside the cell by AuNSs uptake and correspondent geometrical configuration generating dimers are able to enhance locally electromagnetic fields. The SERS signals inside such regions permit the unequivocal identification of cancer-specific biochemical components such as hydroxyapatite, phenylalanine, and protein denaturation due to disulfide bonds breaking between cysteine links or proline.

Advanced Infrared Technology and Applications: introduction

This special issue of Applied Optics on Advanced Infrared Technology and Applications collects significantly expanded refereed papers presented at the conference of the same name, held in Quebec City, Canada, Sept. 27 to Sept. 30, 2017. All the authors who participated at the conference were contacted and invited to contribute to this special issue. Furthermore, the AO dedicated issue on AITA was open to contributions from other practitioners of IR, through direct contact and a call for papers published in AO.

Advances in Infrared Technology and Applications: introduction

The special issue of Applied Optics on Advanced Infrared Technology and Applications(AITA) arose out of the biannual conference of the same name, most recently held in Pisa, Italy, 29 September to 2 October, 2015.

Detection and localization of gold nanoshells inside cells: near-field approximation

The optical properties of metal nanoparticles play a fundamental role for their use in a wide range of applications. In hyperthermia treatment, for example, gold nanoshells (NSs, dielectric core+gold shell) pre-embedded in a cancer cell absorb energy when exposed to appropriate wavelengths of a laser beam and heat up, thereby destroying the cancer cell. In this process, nevertheless, healthy tissues (not targeted by the NSs) along the laser path are not affected; this is because most biological soft tissues have a relatively low light absorption coefficient in the near-infrared (NIR) regions-a characteristic known as the tissue optical window. Over such a window, NIR light transmits through the tissues with scattering-limited attenuation and minimal heating, thereby avoiding damage to healthy tissues. As a consequence, the identification of NSs assumed a fundamental role for the further development of such cancer treatment. Recently, we have demonstrated the possibility to identify 100-150 nm diameter gold NSs inside mouse cells using a scanning near-optical microscope (SNOM). In this paper, we provide a numerical demonstration that the SNOM is able to locate NSs inside the cell with a particle-aperture distance of about 100 nm. This result was obtained by developing an analytical approach based on the calculation of the dyadic Green function in the near-field approximation. The implications of our findings will remarkably affect further investigations on the interaction between NSs and biological systems.

Installing tungsten Fischer carbene complexes into a calixarene framework

The first examples of calix[4]arene-based Fischer carbene complexes are here reported. The organometallic calixarene complexes showed a promising cytotoxicity towards human tumor cell lines.

Ordered rippling of polymer surfaces by nanolithography: influence of scan pattern and boundary effects

We demonstrate how AFM nanolithography, with a proper choice of scan pattern, can induce an exceptionally ordered alignment of ripples on the surface of polymer films on the first scan. By analogy with the manipulation of nanoparticles, the orientation of the ripples is determined by the material flow, which is ultimately fixed by the direction of motion of the probing tip. This makes a raster scan pattern the best choice for orienting the ripples, as opposed to the zigzag scan pattern commonly adopted by most AFM setups. Our hypothesis is substantiated by a series of measurements on a solvent-enriched ultrathin film of PET, which allowed ripple formation on the first scan. We also show how the ripple orientation is significantly modified by the boundary conditions appearing when nanolithography is performed on circular, triangular and L-shaped areas on the polymer surface.

NEW BIOARTIFICIAL SYSTEMS AND BIODEGRADABLE SYNTHETIC POLYMERS FOR CARDIAC TISSUE ENGINEERING: A PRELIMINARY SCREENING

The aim of this work was the preparation and characterization of new polymeric biomaterials for application in myocardial tissue engineering. The attention was firstly focused on new bioartificial polymeric systems, with the aim to combine the features of synthetic polymers with the specific cell and tissue compatibility of biopolymers. In this work, alginate, collagen, and gelatin were used as the natural component and poly(N-isopropylacrylamide) was used as the synthetic component. The characterization included morphological, topographical, and mechanical analyses, thermogravimetric characterization, infrared spectroscopy, and cell culture tests. For the biological characterization, C2C12 myoblasts were cultured on different materials and cell adhesion, proliferation, and differentiation were evaluated. The morphological, topographical, and mechanical analyses, as well as the biological characterization, were also applied to a tri-block poly(ester-ether-ester) copolymer, obtained by reaction of preformed poly(ethylene glycol) with ε-caprolactone, and a novel poly(ester urethane) obtained by using an L-lisine-derived diisocyanate, giving nontoxic degradation products. The encouraging results obtained in this work allowed us to select some of the new bioartificial polymers, the synthetic tri-block copolymer, and the polyurethane as potential good materials to prepare scaffolds for myocardial tissue engineering.

Morpho-functional characterization of human mesenchymal stem cells from umbilical cord blood for potential uses in regenerative medicine

Mesenchymal stem cells (MSCs) represent a promising source of progenitor cells having the potential to repair and to regenerate diseased or damaged skeletal tissues. Bone marrow (BM) has been the first source reported to contain MSCs. However, BM-derived cells are not always acceptable, due to the highly invasive drawing and the decline in MSC number and differentiative capability with increasing age. Human umbilical cord blood (UCB), obtainable by donation with a noninvasive method, has been introduced as an alternative source of MSCs. Here human UCB-derived MSCs isolation and morpho-functional characterization are reported. Human UCB-derived mononuclear cells, obtained by negative immunoselection, exhibited either an osteoclast-like or a mesenchymal-like phenotype. However, we were able to obtain homogeneous populations of MSCs that displayed a fibroblast-like morphology, expressed mesenchym-related antigens and showed differentiative capacities along osteoblastic and early chondroblastic lineages. Furthermore, this study is one among a few papers investigating human UCB-derived MSC growth and differentiation on three-dimensional scaffolds focusing on their potential applications in regenerative medicine and tissue engineering. UCB-derived MSCs were proved to grow on biodegradable microfiber meshes; additionally, they were able to differentiate toward mature osteoblasts when cultured inside human plasma clots, suggesting their potential application in orthopedic surgery.

Acrylic Copolymers as Candidates for Drug-Eluting Coating of Vascular Stents

The aim of the present work is the synthesis and characterization of polymer materials showing good adhesion, drug loading, and delivery properties, for potential cardiovascular application. In particular, poly(methylmethacrylate-co-acrylic acid) copolymers are prepared in different compositions by a radical polymerization and investigated as potential materials to coat metallic stents and to carry out a local drug release. Films obtained by dissolving the copolymer in an appropriate organic solvent (also loaded with an anti-restenosis drug, such as tacrolimus) are investigated: physicochemical properties, adhesiveness to metallic stent material, and kinetics of drug release in physiological environment are studied.

Degradable block polyurethanes from nontoxic building blocks as scaffold materials to support cell growth and proliferation

Linear degradable polyurethanes were prepared and proposed for tissue engineering applications. Biocompatible segments were selected for the synthesis to promote their integration with the biological environment. Physicochemical and morphological characterization (SEC, DSC, DMTA, AFM) revealed that the properties of these polymeric systems can be easily tuned by varying the nature and the composition of the constituent segments. In vitro biological assays (citotoxicity, fibroblast adhesion, and proliferation) showed that all polymers are not toxic, promoting the adhesion and proliferation of fibroblast cells, with slight differences depending on the material hydrophilicity.

A Micro/Nanoscale Surface Mechanical Study on Morpho-Functional Changes in Multilineage-Differentiated Human Mesenchymal Stem Cells

In recent years MSCs have become a very attractive tool in tissue engineering and regenerative medicine because of their ability to be committed along several lineages through chemical or physical stimuli. Nevertheless their therapeutic potential and plasticity are not yet totally understood. This report describes the use of AFM together with conventional microscopies to obtain mechanical information on cell surfaces and deposited extra cellular matrix molecules, after inducing the differentiation of human MSCs towards three typical mesoderm phenotypes. The aim is to correlate morphological, functional, and mechanical aspects of human MSCs to obtain a deeper understanding of their great potential.

Influence of a reduced mobility layer on the structural relaxation dynamics of aluminum capped ultrathin films of poly(ethylene terephthalate)

The structural dynamics of ultrathin polymer films of poly(ethylene terephthalate) capped between aluminum electrodes have been investigated by dielectric relaxation spectroscopy. A deviation from bulk behavior, appearing as an increase of the relaxation time at a fixed temperature, is observed for films of thickness below 35 nm. The slowing down acts as a constant shift factor independent from the temperature, and the fragility is constant. The interfacial energy between aluminum and poly(ethylene terephthalate) is calculated to be 3 mJ/m2, confirming a strong interaction between polymer and substrate, which leads to the presence of a layer characterized by a reduced mobility at their interfaces. We proposed a mathematical schematization of a multylayer model that allowed qualitative reproduction of the observed thickness dependences of the static and dynamic properties. In terms of such a model, the upper limit for the thickness of the reduced mobility layer was estimated as 20 nm. The conditions to extend the proposed model to different observables are finally suggested.