The biomineralization process is a mechanism inherent to all organisms of the Earth. Throughout the decades, diverse works have reported that the origin of life is tied to crystals, specifically to biominerals of silica that catalyzed RNA, and had some influence in the homochirality. Although the mechanism by which crystals surfaces (minerals) gave origin to life has not yet been proven, the truth is that, up to the present, biominerals are being synthetized by the organisms of different kingdoms in two basic ways: biologically induced and biologically controlled biomineralization. Paradoxically, this fact makes a fundamental difference between inorganic materials and those formed by living organisms, as the latter are associated with macromolecules that are bound to the mineral phase. Conserving growth and formation of these biogenic organic crystals inside cells is a fascinating subject that has been studied mainly in some of the kingdoms, like Monera (bacteria), Fungi (yeasts), and Animalia (Homo sapiens). Notwithstanding in the Plantae kingdom, the formation, conservation, and functions of crystals has not yet been completely elucidated and described, which is of particular relevance because life on Earth, as we know it, would not be possible without plants. The aim of the present work is to revise the different crystals of calcium oxalate synthetized inside the cells of plants, as well as to identify the mechanism of their formation and their possible functions in plants. The last part is related to the existence of certain proteins called phototropins, which not only work as the blue-light sensors, but they also play an important role on the accumulation of calcium in vacuoles. This new trend is shortly reviewed to explain the characteristics and their plausible role in the calcium uptake along with the biomineralization processes.

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We present an experimental study of the resonance modes in dual-periodical multilayer structures based on porous silicon. These multilayered structures are composed by stacking N times two substructures A, and B, i.e., A n B m N . The A n and B m are in turn composed of two different period units, a and b, respectively, where subscripts n and m are the period number in the a and b substructures. Both substructures a and b consist of a pair of alternating layers with high and low refractive indices n 1 and n 2 , respectively. The thickness parameters of the dielectric layers in a and b are all different. We observe several resonance transmission peaks due to the periodical repetition of the A n B m structure. The number of resonance peaks, their full width at half-maximum (FWHM), etc., can be controlled by selecting the structural parameters of the system. The experimental data are in good agreement with those calculated using the transfer matrix method. These optical superlattices are very promising, since they can be designed so that the reflectance response presents a determined number of resonance modes in the most important window for optical communications, making them good candidates for direct applications.

In this work we report the effect of introducing pyruvic acid (PA) in the growing process of silica-carbonate biomorphs. Gas-diffusion and single-phase methods were performed, and different concentrations of pyruvic acid were tested. Moreover, influence of UV radiation on the morphogenesis of the samples was analyzed. Since PA decomposes in CO2 and other compounds under UV radiation, here we demonstrate that PA decomposition enables a source of carbonate ions to induce the precipitation of silica-carbonate biomorphs in absence of environmental CO2. We also found that high concentrations [0.5 M] of PA inhibit the formation of biomorphs, while lower concentrations [0.01 M] results in common life-like structures. However [0.1 M] of PA provokes the precipitation of carbonates of alkaline earth metals in non-usual crystalline habits, i.e., semi-spherical smoothed shapes sized between 10 and 70 µm and homogeneously growth on a glass substrate.

In this work, we report the experimental results and theoretical analysis of strong localization of resonance transmission modes generated by hybrid periodic/quasiperiodic heterostructures (HHs) based on porous silicon. The HHs are formed by stacking a quasiperiodic Fibonacci (FN) substructure between two distributed Bragg reflectors (DBRs). FN substructure defines the number of strong localized modes that can be tunable at any given wavelength and be unfolded when a partial periodicity condition is imposed. These structures show interesting properties for biomaterials research, biosensor applications and basic studies of adsorption of organic molecules. We also demonstrate the sensitivity of HHs to material infiltration.