Ag2 S Biocompatible Ensembles as Dual OCT Contrast Agents and NIR Ocular Imaging Probes.

Ag2 S nanoparticles (NPs) emerge as a unique system that simultaneously features in vivo near-infrared (NIR) imaging, remote heating, and low toxicity thermal sensing. In this work, their capabilities are extended into the fields of optical coherence tomography (OCT), as contrast agents, and NIR probes in both ex vivo and in vivo experiments in eyeballs. The new dual property for ocular imaging is obtained by the preparation of Ag2 S NPs ensembles with a biocompatible amphiphilic block copolymer. Rather than a classical ligand exchange, where surface traps may arise due to incomplete replacement of surface sites, the use of this polymer provides a protective extra layer that preserves the photoluminescence properties of the NPs, and the procedure allows for the controlled preparation of submicrometric scattering centers. The resulting NPs ensembles show extraordinary colloidal stability with time and biocompatibility, enhancing the contrast in OCT with simultaneous NIR imaging in the second biological window.

Automatic segmentation and classification of Papanicolaou-stained cells and dataset for oral cancer detection.

BACKGROUND AND OBJECTIVE: Papanicolaou staining has been successfully used to assist early detection of cervix cancer for several decades. We postulate that this staining technique can also be used for assisting early detection of oral cancer, which is responsible for about 300,000 deaths every year. The rational for such claim includes two key observations: (i) nuclear atypia, i.e., changes in volume, shape, and staining properties of the cell nuclei can be linked to rapid cell proliferation and genetic instability; and (ii) Papanicolaou staining allows one to reliably segment cells' nuclei and cytoplasms. While Papanicolaou staining is an attractive tool due to its low cost, its interpretation requires a trained pathologist. Our goal is to automate the segmentation and classification of morphological features needed to evaluate the use of Papanicolaou staining for early detection of mouth cancer. METHODS: We built a convolutional neural network (CNN) for automatic segmentation and classification of cells in Papanicolaou-stained images. Our CNN was trained and evaluated on a new image dataset of cells from oral mucosa consisting of 1,563 Full HD images from 52 patients, annotated by specialists. The effectiveness of our model was evaluated against a group of experts. Its robustness was also demonstrated on five public datasets of cervical images captured with different microscopes and cameras, and having different resolutions, colors, background intensities, and noise levels. RESULTS: Our CNN model achieved expert-level performance in a comparison with a group of three human experts on a set of 400 Papanicolaou-stained images of the oral mucosa from 20 patients. The results of this experiment exhibited high Interclass Correlation Coefficient (ICC) values. Despite being trained on images from the oral mucosa, it produced high-quality segmentation and plausible classification for five public datasets of cervical cells. Our Papanicolaou-stained image dataset is the most diverse publicly available image dataset for the oral mucosa in terms of number of patients. CONCLUSION: Our solution provides the means for exploring the potential of Papanicolaou-staining as a powerful and inexpensive tool for early detection of oral cancer. We are currently using our system to detect suspicious cells and cell clusters in oral mucosa slide images. Our trained model, code, and dataset are available and can help practitioners and stimulate research in early oral cancer detection.

Tuning the load of gold and magnetic nanoparticles in nanogels through their design for enhanced dual magneto-photo-thermia.

We describe a novel synthesis allowing one to enhance the load of magnetic nanoparticles and gold nanorods in nanogels. Two different structures, simple cores and core-shell, were synthesized and their heating properties upon alternating magnetic field or laser exposure are compared. Remarkably, the core-shell structure showed a greater heating capacity in the two modalities.

In vivo time-course biocompatibility assessment of biomagnetic nanoparticles-based biomaterials for tissue engineering applications.

Novel artificial tissues with potential usefulness in local-based therapies have been generated by tissue engineering using magnetic-responsive nanoparticles (MNPs). In this study, we performed a comprehensive in vivo characterization of bioengineered magnetic fibrin-agarose tissue-like biomaterials. First, in vitro analyses were performed and the cytocompatibility of MNPs was demonstrated. Then, bioartificial tissues were generated and subcutaneously implanted in Wistar rats and their biodistribution, biocompatibility and functionality were analysed at the morphological, histological, haematological and biochemical levels as compared to injected MNPs. Magnetic Resonance Image (MRI), histology and magnetometry confirmed the presence of MNPs restricted to the grafting area after 12 weeks. Histologically, we found a local initial inflammatory response that decreased with time. Structural, ultrastructural, haematological and biochemical analyses of vital organs showed absence of damage or failure. This study demonstrated that the novel magnetic tissue-like biomaterials with improved biomechanical properties fulfil the biosafety and biocompatibility requirements for future clinical use and support the use of these biomaterials as an alternative delivery route for magnetic nanoparticles.

Generation of genipin cross-linked fibrin-agarose hydrogel tissue-like models for tissue engineering applications.

The generation of biomimetic and biocompatible artificial tissues is the basic research objective for tissue engineering (TE). In this sense, the biofabrication of scaffolds that resemble the tissues' extracellular matrix is an essential aim in this field. Uncompressed and nanostructured fibrin-agarose hydrogels (FAH and NFAH, respectively) have emerged as promising scaffolds in TE, but their structure and biomechanical properties must be improved in order to broaden their TE applications. Here, we generated and characterized novel membrane-like models with increased structural and biomechanical properties based on the chemical cross-linking of FAH and NFAH with genipin (GP at 0.1%, 0.25%, 0.5% and 0.75%). Furthermore, the scaffolds were subjected to rheological (G, G', G″ modulus), ultrastructural and ex vivo biocompatibility analyses. Results showed that all GP concentrations increased the stiffness (G) and especially the elasticity (G') of FAH and NFAH. Ultrastructural analyses demonstrated that GP and nanostructuration of FAH allowed us to control the porosity of FAH. In addition, biological studies revealed that higher concentration of GP (0.75%) started to compromise the cell function and viability. Finally, this study demonstrated the possibility to generate natural and biocompatible FAH and NFAH with improved structural and biomechanical properties by using 0.1%-0.5% of GP. However, further in vivo studies are needed in order to demonstrate the biocompatibility, biodegradability and regeneration capability of these cross-linked scaffolds.

Biocompatible magnetic core-shell nanocomposites for engineered magnetic tissues.

The inclusion of magnetic nanoparticles into biopolymer matrixes enables the preparation of magnetic field-responsive engineered tissues. Here we describe a synthetic route to prepare biocompatible core-shell nanostructures consisting of a polymeric core and a magnetic shell, which are used for this purpose. We show that using a core-shell architecture is doubly advantageous. First, gravitational settling for core-shell nanocomposites is slower because of the reduction of the composite average density connected to the light polymer core. Second, the magnetic response of core-shell nanocomposites can be tuned by changing the thickness of the magnetic layer. The incorporation of the composites into biopolymer hydrogels containing cells results in magnetic field-responsive engineered tissues whose mechanical properties can be controlled by external magnetic forces. Indeed, we obtain a significant increase of the viscoelastic moduli of the engineered tissues when exposed to an external magnetic field. Because the composites are functionalized with polyethylene glycol, the prepared bio-artificial tissue-like constructs also display excellent ex vivo cell viability and proliferation. When implanted in vivo, the engineered tissues show good biocompatibility and outstanding interaction with the host tissue. Actually, they only cause a localized transitory inflammatory reaction at the implantation site, without any effect on other organs. Altogether, our results suggest that the inclusion of magnetic core-shell nanocomposites into biomaterials would enable tissue engineering of artificial substitutes whose mechanical properties could be tuned to match those of the potential target tissue. In a wider perspective, the good biocompatibility and magnetic behavior of the composites could be beneficial for many other applications.

Ex vivo characterization of a novel tissue-like cross-linked fibrin-agarose hydrogel for tissue engineering applications.

The generation of biomaterials with adequate biomechanical and structural properties remains a challenge in tissue engineering and regenerative medicine. Earlier research has shown that nanostructuration and cross-linking techniques improved the biomechanical and structural properties of different biomaterials. Currently, uncompressed and nanostructured fibrin-agarose hydrogels (FAH and NFAH, respectively) have been used successfully in tissue engineering. The aim of this study was to investigate the possibility of improving the structural and biomechanical properties of FAH and NFAH by using 0.25% and 0.5% (v/v) glutaraldehyde (GA) as a cross-linker. These non-cross-linked and cross-linked hydrogels were subjected to structural, rheological and ex vivo biocompatibility analyses. Our results showed that GA cross-linking induced structural changes and significantly improved the rheological properties of FAH and NFAH. In addition, ex vivo biocompatibility analyses demonstrated viable cells in all conditions, although viability was more compromised when 0.5% GA was used. Our study demonstrates that it is possible to control fiber density and hydrogel porosity of FAH and NFAH by using nanostructuration or GA cross-linking techniques. In conclusion, hydrogels cross-linked with 0.25% GA showed promising structural, biochemical and biological properties for use in tissue engineering.

Combining magnetic hyperthermia and photodynamic therapy for tumor ablation with photoresponsive magnetic liposomes.

The ongoing nanotech revolution has the potential to transform diagnostic and therapeutic methods. Stimuli-triggered nanotherapies based on remotely activated agents have become attractive alternatives to conventional chemotherapy. Herein, we designed an optimized smart nanoplatform based on dually loaded hybrid liposomes to achieve enhanced tumor therapy. The aqueous core was highly loaded with iron oxide nanoparticles, while the lipid bilayer was supplied with a photosensitizer payload. The double cargo translated into double functionality: generation of singlet oxygen under laser excitation and heat production under alternating magnetic field stimulation, coupling photodynamic therapy (PDT) to magnetic hyperthermia (MHT). These liposomes address both therapeutic agents within tumor cells, and the combined PDT/MHT therapy resulted in complete cancer cell death in vitro while total solid-tumor ablation was achieved in an in vivo rodent model.