Pablo Acedo

Plasma-derived fibrin hydrogels are widely used in tissue engineering because of their excellent biological properties. Specifically, human plasma-derived fibrin hydrogels serve as 3D matrices for autologous skin graft production, skeletal muscle repair, and bone regeneration. Nevertheless, for advanced applications such as in vitro skin equivalents and engineered grafts, the intrinsic limitations of native fibrin hydrogels in terms of long-term mechanical stability and resistance to degradation need to be addressed to enhance the usefulness and application of these hydrogels in tissue engineering. In this study, we chemically modified plasma-derived fibrin by incorporating succinimidyl alginate (SA), a version of alginate chemically modified to introduce reactive succinimidyl groups. These NHS ester groups (N-hydroxysuccinimide esters), attached to the alginate backbone, are highly reactive toward the primary amine groups present in plasma proteins such as fibrinogen. When mixed with plasma, the NHS groups covalently bond to the amine groups in fibrin, forming stable amide linkages that reinforce the fibrin network during hydrogel formation. This chemical modification improved mechanical properties, reduces contraction, and enhanced the stability of the resulting hydrogels. Hydrogels were prepared with a final fibrinogen concentration of 1.2 mg/mL and SA concentrations of 0.5, 1, 2, and 3 mg/mL. The objective was to evaluate whether this modification could create a more stable matrix suitable for supporting skin tissue development. The mechanical and microstructure properties of these new hydrogels were evaluated, as were their biocompatibility and potential to create 3D skin models in vitro. Dermo-epidermal skin cultures with primary human fibroblast and keratinocyte cells on these matrices showed improved dermal stability and better tissue structure, particularly SA concentrations of 0.5 and 1 mg/mL, as confirmed by H&E (Hematoxylin and Eosin) staining and immunostaining assays. Overall, these results suggest that SA-functionalized fibrin hydrogels are promising candidates for creating more stable in vitro skin models and engineered skin grafts, as well as for other types of engineered tissues, potentially.

Millimeter-wave and terahertz hyperspectral imaging is expected to play an important role in many applications, from industrial product inspection to security. However, current systems suffer from various limitations in different aspects of their performance that prevent them from having a noticeable impact on our lives. Here we present the first direct multi-spectral dual-comb imaging system operating in the millimeter-wave frequency range in which both spatial and spectral information are retrieved simultaneously. This technique can address many of the currently existing technological weaknesses by providing accurate and high-resolution spectral measurements, maximum adaptability for application-tailored operation and real-time operation capabilities. Several proof-of-concept demonstrations validate the instrument's ability to provide spectro-imaging characterizations on various materials with noteworthy performance levels.

The use of nitrogen-vacancy (NV) centers in diamond as a non-invasive platform for hyperpolarizing nuclear spins in molecular samples is a promising area of research with the potential to enhance the sensitivity of nuclear magnetic resonance (NMR) experiments. Transferring NV polarization out of the diamond structure has been achieved on nanoscale targets using dynamical nuclear polarization methods, but extending this polarization transfer to relevant NMR volumes poses significant challenges. One major technical hurdle is the presence of paramagnetic defects in the diamond surface which interfere with polarization outflow. However, these defects can be harnessed as intermediaries for the interaction between NVs and nuclear spins. We present a method that benefits from existing microwave sequences, namely the PulsePol, to transfer polarization efficiently and robustly using dangling bonds or other localized electronic spins, with the potential to increase polarization rates under realistic conditions.

This work presents the development of a refractive index sensing methodology for measuring carbon dioxide concentrations, considering the effect of temperature environment. We propose and demonstrate, using simulations, the use of tapered and coated Long Period Gratings as a way to enhance the refractive index sensitivity. In addition, artificial neural networks were used to improve the estimation of carbon dioxide concentration, considering the crosssensitivity effect with temperature.

In this research, we present an analysis of a photonic integrated frequency shifter as a stage for a THz dual comb generator. We studied the performance of the PIC by simulating it with standard building blocks, and aimed toward an improvement of the output signal quality. We revised two approaches of the PIC by simulating two modes of generating a double side band modulation suppressed carrier (DSB-SC) with a Mach Zehnder modulator structure (MZM). One approach was using a single Electro-Optic Phase Modulator (EOPM) on an MZM structure (SE-MZM), and the other one was using Double EOPM (DE-MZM). We found a cleaner spectrum with the DE-MZM, since this structure is usually applied to reduce the chirp effect in optical communication systems. We obtained 23 dB of side mode suppression ratio SMSR with one filter, and 44 dB of SMSR with a two-stage filter. In the case of DE-MZM, we obtained a clean tone on intermediate frequency (IF) free of spurious sidebands and comb in IF frequency with 10 dB more power compared to SE-MZM.

Procalcitonin (PCT) is considered a sepsis and infection biomarker. Herein, an interdigitated electrochemical immunosensor for the determination of PCT has been developed. The interdigitated electrode was made of the laser-engraved graphene electrode decorated with gold (LEGE/Au_nano). The scanning electron microscopy indicated the LEGE/Au_nano has been fabricated successfully. After that, the anti-PTC antibodies were immobilized on the surface of the electrode by using 3-mercaptopropionic acid. The electrochemical performance of the fabricated immunosensor was studied using electrochemical impedance spectroscopy (EIS). The EIS method was used for the determination of PCT in the concentration range of 2.5–800 pg/mL with a limit of detection of 0.36 pg/mL. The effect of several interfering agents such as the C reactive protein (CRP), immunoglobulin G (IgG), and human serum albumin (HSA) was also studied. The fabricated immunosensor had a good selectivity to the PCT. The stability of the immunosensor was also studied for 1 month. The relative standard deviation (RSD) was obtained to be 5.2%.