Band 3, Heft 1

We induced mechanical self-oscillations in a microcavity structure made of porous silicon onedimensional photonic crystals (PSi-1DPC) with an air gap. The electromagnetic force generated within the whole photonic structure, by light with a wavelength of 633 nm, is enough to overcome energy losses and sustain selfoscillations. From these mechano-optical measurements we estimated the stiffness and Young’s modulus of porous silicon and compared the results with values reported elsewhere and with values estimated herein by a mechanical method.We obtained good agreement between all values.

The continuous generation of rice husk biomass makes this waste biomass a consistent and renewable resource for carbon zero power generation. Biochar from the power generation industry could be further utilized and converted into activated carbon through a simple activation process, foregoing the conventional carbonization process. Complete combustion of rice husk into rice husk ash could be subsequently processed into sodium silicate with little difficultly since more than 90%of the rice husk ash constituent is silica. Sodium silicate is used mainly as a precursor for both the synthesis of mesoporous silica and zeolite. This paper reviews on the various nanoporous adsorbents derived from a single rice husk biomass.

Porous silicon (PSi) can activate (sensitize) biochemical reactions and physical processes of the energy dissipation under excitation (stimulus) by light illumination, ultrasound (US), and electromagnetic radiofrequency (RF) irradiation. Photosensitized biochemical effects of PSi layers and nanoparticles (NPs)were explored in numerous physical studies and biomedical experiments in vitro. The photothermal sensitizing with mesoporous PSi NPs was demonstrated to be efficient for the hyperthermia of cancer cells and tumors in small animal models. The sonosensitizing properties of bare PSi NPs and dextran-coated ones were revealed by both the physical studies and biomedical experiments, which indicated a good prospect for their applications in sonodynamic therapy of cancer. RF-induced hyperthermia sensitized by PSi NPs has been successfully used to destroy cancer cells and tumors in vitro and in vivo, respectively. Here, we review the results on the preparation, physical properties, and applications of PSi NPs as sensitizers for mild therapy of cancer.

Supercapacitors (SC) are energy storage devices with higher power but lower energy density than Li batteries. SC store energy based on two mechanisms: double layer capacitance (non-Faradaic) and pseudocapacitance (faradaic). Porous carbon materials have been extensively used as electrodes in SC, where their great surface area and pore size distribution have been the main properties for capacitance improvement. Nevertheless, these properties have shown limitations since they cannot be highly increased without losing electric conductivity, which is detrimental for the power requirements of SC. An alternative approach to increase capacitance has been the surface modification of carbon materials by introducing faradaic contributions. In this mini review, the effect of surface area, porosity, surface modification by doping or functionalization, and introduction of electroactive oxides are discussed to show how these factors influences the intrinsic capacitance values of different carbon materials; and some examples from our work are provided. The manipulation of such properties, on carbon materials (porosity and /or surface chemistry) not only are useful for devices such as SC, but also are very useful for a wide variety of Bio-applications (Bio-sensors, labelling and drug delivery, impregnation with microorganisms for its use as biochar, or for bio-fuel cells, etc.)

The objective of this work is to elucidate the possibility to passivate the surface states of porous Si (PSi) by thermal oxidation to be used as a passive host matrix. It is known that a large contribution to the Photoluminescence (PL) of PSi comes from defects at the surface. This PL could overlap the PL of guest materials making it difficult to identify the details of the PL spectrum of the guest. We report on an experimental study about the effect of thermal oxidation at low temperature on the PL of PSi and on the functionalization of oxidized PSi with fluorescein. The background PL is minimized allowing a better detection of fluorescein molecules adsorbed on oxidized PSi.

In this work, the electrodeposition and characterization of 1D CuInSe2 (CIS) nanostructures formed by the assistance of porous silicon (PSi) templates is presented. The formation of CIS was found to be potential dependent on the specific substrate being used. The filling process of the pores of PSi template was studied directly by the current transient response during electrodeposition of nanostructured CIS and results were compared with FESEM images. CIS nanostructures were fully characterized by using FE-SEM, FIB, XRD, and Raman spectroscopy, in order to know their physical properties.

We report on the formation of different carbon nanostructures by ultrasonication of graphite in DMF upon the addition of 3 different small molecules: ferrocene carboxylic acid, dimethylamino methyl-ferrocene, and benzyl aldehyde. Our results confirm that acoustic cavitation in organic solvents generates free radicals which enable or are involved in secondary reactions. During the ultrasonication process, the addition of small molecules induces the formation of different carbon nanostructures mainly depending on the chemical nature of the molecule, as observed by transmission electron microscopy (TEM). Raman spectroscopy analysis confirms that small molecules act as radical scavengers reducing the damage caused by cavitation to graphene sheets producing long nanoribbons, squared sheets, or carbon nanoscrolls. Importantly, this strategy allows the production of different carbon nanostructures in liquid-phase making them readily available for their chemical functionalization or for their incorporation into hybrids materials enabling the development of new advanced biological applications.

Nanomaterials are applied with great success in biomedical applications as templates for the development of new generation devices, which can be used to solve current health problems. These new nanoscale systems are designed with multifunctions to perform specific and selective tasks. One of the most important applications of this new nanotechnology; focuses on developing new systems for the controlled release of drugs, mainly due to their capability to improve the temporal and spatial presentation of drugs in the body and their ability to protect them from physiological degradation or elimination. Hydrogels, porous silicon (PSi), and PSi-composites have been widely adopted in this field due to their biological, morphological, and physicochemical properties; which can be tuned to obtain sensitive responses to physiological stimuli. Despite the fact that some recent academic papers have shown the benefits of these nanomaterials in a wide range of biological applications, more in vivo studies are needed to take these hybrid systems towards clinical trials. In this mini-review some of the hydrogels, PSi, and PSi-composites latest applications and prospects in this field of science are presented.

Vaccination is a crucial approach to eradicate and control amyriad of infectious and non-communicable diseases. Subunit vaccines are considered the most convenient approach for vaccine formulation; however, the development of new adjuvants and vaccine delivery vehicles to improve the immunogenicity of such formulations is needed. The authors of this review describe the recent application of porous silicon particles (PSiP) as both a potential vaccine delivery vehicle and adjuvant. PSiP are attractive for this application due to its safety, biodegradability and compatibility for functionalization. Herein, the development of multi-epitope cancer vaccines is discussed as an example on how PSiP are promising materials for the development of innovative vaccines.

The aim of this work was to evaluate the effects induced by single walled carbon nanotubes (SWCNTs) on the airway smooth muscle tone, using an isolated rat tracheal rings model and monitoring nitric oxide (NO) as a possible mediator involved in the effects. Exposure of tracheal rings to SWCNTs did not modify the smooth muscle tone per se; however,when the ringswere pre-treated with the contractile agent acetylcholine (ACh), all SWCNTs concentrations (0.1-10 μg/mL) induced a transient contractile effect similar to that induced by ACh alone. Interestingly, the NO production was not modified by SWCNTs regardless of the presence of ACh 10 μM. Thus, the data suggest that NO is not involved in the airway smooth muscle contraction induced by SWCNTs. Further investigations are required to understand the effects, mediator(s) and mechanisms of action induced by this type of porous nanomaterial, as well as their fine interactions with the respiratory system structures.