Volume 4, Issue 1

Biocompatible materials have a great potential to engineer immunology towards therapeutic applications. Among them, porous materials have attracted much attention for immune modulation due to their unique porous structure. The large surface area and pore space offer high loading capacity for various payloads including peptides, proteins and even cells. We first introduce recent developments in the porous particles that can deliver immunomodulatory agents to antigen presenting cells for immunomodulation. Then, we review recent developments in the porous implants that can act as a cellattracting/ delivering platform to generate artificial immunomodulatory environments in the body. Lastly, we summarize recent findings of immunogenic porous materials that can induce strong immune responses without additional adjuvants. We also discuss future direction of porous materials to enhance their immunomodulatory potential for immunotherapeutic applications.

Graphene oxide (GO) is a single-atom-thick and two-dimensional carbon material that has attracted great attention because of its remarkable electronic, mechanical, chemical and thermal properties. GO could be an ideal substrate for the development of label-free optical biosensors, however, its weak photoluminescence (PL) strongly limits the use for this purpose. In this study, we developed a covalent chemical strategy in order to obtain a hybrid GO-macroporous silicon (PSi) structure for biomedical applications. The realized structure was characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM)water contact angle (WCA) measurements, Fourier transform infrared spectroscopy (FTIR) and label- free optical methods based on spectroscopic reflectometry and PL analysis. Investigations showed that the hybrid structure is suitable as a transducer material for biosensing applications due to its peculiar optical properties resulting from the combination of GO and PSi.

Porous Silicon (PSi) is a groundbreaking material because its physicochemical properties can be customized through its porosity. This means that monitoring and control of the growing parameters allows the fabrication of PSi-based systems with controlled properties. Interferometry and photoacoustics are non -invasive, non - contact, real-time (in-situ) techniques used to characterize the phenomena that takes place during the formation of PSi. This work presents the mathematical and experimental aspects related to the implementation of the techniques mentioned above, which are meant to characterize the PSi growth in fluoride-based electrolyte media. These methods can determine macroscopic parameters of PSi such as thickness, porosity profile trough effective medium approximation (EMA), refractive index, etching rate, and RMS roughness under 100 nm. The monitoring ability of these techniques is strongly dependent on the wavelength of radiation used. However, it is possible to monitor thickness from λ 0 /4 to ∼ 1/ α 0 , where α 0 is the optical absorption coefficient at λ 0 . Also, these techniques can be implemented as feedback control on the etching processes for fabrication of PSi.

Laser ablation with nanosecond-pulsed Nd:YAG laser irradiation combined with anisotropic alkaline etching of Si wafers creates 4-20 μm macropores that extend all the way through the wafer. The walls of these macropores are crystallographically defined by the interaction of the anisotropy of the etchant with the orientation of the single-crystal silicon substrate: rectangular/octagonal on Si(001), parallelepiped on Si(110), triangular/hexagonal on Si(111). Laser ablation can create pillars with peak-tovalley heights of over 100 μm. However, with nanosecondpulsed irradiation at 532 nm, the majority of this height is created by growth above the original plane of the substrate whereas for 355 nm irradiation, the majority of the height is located below the initial plane of the substrate. Repeated cycles of ablation and alkaline etching are required for membrane formation. Therefore, irradiating with 355 nm maintained better the crystallographically defined nature of the through-pores whereas irradiation at 532 nm led to more significant pore merging and less regularity in the macropore shapes. Texturing of the substrates with alkaline-etching induced pyramids or near-field modulation of the laser intensity by diffraction off of a grid or grating is used to modulate the growth of ablation pillars and the resulting macropores. Texturing causes the macropores to be more uniform and significantly improves the yield of macropores. The size range of these macropores may make them useful in single-cell biological studies.