Polysilicon-chromium-gold intracellular chips for multi-functional biomedical applications

The development of micro- and nanosystems for their use in biomedicine is a continuously growing field. One of the major goals of such platforms is to combine multiple functions in a single entity. However, achieving the design of an efficient and safe micro- or nanoplatform has shown to be strongly influenced by its interaction with the biological systems, where particle features or cell types play a critical role. In this work, the feasibility of using multi-material pSi-Cr-Au intracellular chips (MMICCs) for multifunctional applications by characterizing their interactions with two different cell lines, one tumorigenic and one non-tumorigenic, in terms of biocompatibility, internalization and intracellular fate, has been explored. Moreover, the impact of MMICCs on the induction of an inflammatory response has been assessed by evaluating TNFα, IL1b, IL6, and IL10 human inflammatory cytokines secretion by macrophages. Results show that MMICCs are biocompatible and their internalization efficiency is strongly dependent on the cell type. Finally as a proof-of-concept, MMICCs have been dually functionalized with transferrin and pHrodo™ Red, SE to target cancer cells and detect intracellular pH, respectively. In conclusion, MMICCs can be used as multi-functional devices due to their high biocompatibility, non-inflammatory properties and the ability of developing multiple functions

Intracellular Mechanical Drugs Induce Cell-Cycle Altering and Cell Death

Current advances in materials science have demonstrated that extracellular mechanical cues can define cell function and cell fate. However, a fundamental understanding of the manner in which intracellular mechanical cues affect cell mechanics remains elusive. How intracellular mechanical hindrance, reinforcement, and supports interfere with the cell cycle and promote cell death is described here. Reproducible devices with highly controlled size, shape, and with a broad range of stiffness are internalized in HeLa cells. Once inside, they induce characteristic cell-cycle deviations and promote cell death. Device shape and stiffness are the dominant determinants of mechanical impairment. Device structural support to the cell membrane and centering during mitosis maximize their effects, preventing spindle centering, and correct chromosome alignment. Nanodevices reveal that the spindle generates forces larger than 114 nN which overcomes intracellular confinement by relocating the device to a less damaging position. By using intracellular mechanical drugs, this work provides a foundation to defining the role of intracellular constraints on cell function and fate, with relevance to fundamental cell mechanics and nanomedicine.Peer reviewe

Multi-functionalization of micro- and nanoparticles for cancer theranostics

[eng] Supramolecular chemistry is regarded as a tool to build up nanomaterials through a bottom-up approach. As such, it includes the bio-functionalization of inorganic and metallic surfaces with natural and synthetic receptors to obtain micro-nanotools capable of interacting with biological material and sensing its function, which is the main topic of this research project. Thus, its overall objective is to prepare micro- and nanotools acting as sensors to monitor different cellular parameters in living cells, and deliverers specifically for diagnosis and therapy in cancer cells (theranostics). For this purpose, we used micro- and nanoparticles as substrates, made up of polysilicon or polysilicon-gold and gold nanoparticles, and functionalized them with (bio)molecules. The first objective is to develop a novel microtool for cell adhesion. For this purpose we worked with specially designed polysilicon microparticles of different shapes and sizes, which were chemically modified, to sense carbohydrates present on tumour cell membranes. Chemical modification of these microparticles were performed using lectins, carbohydrate binding proteins which specifically recognizes the carbohydrates present on the cell membranes of specific cells. In the final step, in vitro experiments were carried out in HeLa or Dictyostelium discoideum (Dicty), to assess their ability of adhesion to the cell membrane. In the second objective, the primary goal is to sense intracellular pH in living cells using bi-functional microparticles, in order to differentiate between cancer cells and normal cells. Therefore, for this study we immobilized different pH dependent fluorophores on to a mono-(polysilicon) or bi-functional (polysilicon-gold) microparticles for sensing pH, which were characterized using various techniques. The third objective is the generation and sensing of Reactive oxygen species (ROS) using a bio-photosensitizer for photodynamic therapy. The main goal is to develop and optimize a protocol for immobilizing ROS generator and a ROS sensor on to bi-functional microparticle to sense the production of ROS. The fourth objective is to deliver anionic drugs using gold nanoparticles synthesized using imidazolium based macrocycles. These nanoparticles showed successful incorporation of a model anionic drug and its kinetic release profile was measured at different pHs which showed that the synthesized gold nanoparticles could be used for local drug delivery applications

Macrocyclic imidazolium-based amphiphiles for the synthesis of gold nanoparticles and delivery of anionic drugs

In the present work, we have explored the use of amphiphilic bis-imidazolium based macrocycles and an open chain analog for the successful synthesis of gold nanoparticles (AuNPs). The macrocyclic ligands incorporate hydrophobic chains of different lengths, and the newly synthesized ligands were further used for the synthesis of AuNPs in a biphasic system. The successfully synthesized AuNPs were thoroughly characterized. The sizes of the AuNPs were ca. 8 nm, using macrocyclic ligands bearing two 10 carbon atoms alkyl chains, ca. 5 nm in the case of macrocyclic ligands with two 18 carbon atoms alkyl chains, and ca. 7 nm for the open chain ligand with two 18 carbon atoms alkyl chains. Their possible application as vehicles to load and release anionic drugs (such as sodium ibuprofenate) was also assessed and compared with previously described open chain analogs. In this case, it was observed that the AuNPs had high efficiency in extracting sodium ibuprofenate from an aqueous solution. The application as a drug delivery vehicle was confirmed by in vitro release experiments at different pH values

Intracellular Mechanical Drugs Induce Cell-Cycle Altering and Cell Death

Current advances in materials science have demonstrated that extracellular mechanical cues can define cell function and cell fate. However, a fundamental understanding of the manner in which intracellular mechanical cues affect cell mechanics remains elusive. How intracellular mechanical hindrance, reinforcement, and supports interfere with the cell cycle and promote cell death is described here. Reproducible devices with highly controlled size, shape, and with a broad range of stiffness are internalized in HeLa cells. Once inside, they induce characteristic cell-cycle deviations and promote cell death. Device shape and stiffness are the dominant determinants of mechanical impairment. Device structural support to the cell membrane and centering during mitosis maximize their effects, preventing spindle centering, and correct chromosome alignment. Nanodevices reveal that the spindle generates forces larger than 114 nN which overcomes intracellular confinement by relocating the device to a less damaging position. By using intracellular mechanical drugs, this work provides a foundation to defining the role of intracellular constraints on cell function and fate, with relevance to fundamental cell mechanics and nanomedicine. Keywords: biomaterials; cell cycle; mechanobiology; nanomaterials; nanomedicine; silicon chips