Controlled drug delivery from composites of nanostructured porous silicon and poly(L-lactide)

Porous silicon (pSi) and poly(l-lactide) (PLLA) both display good biocompatibility and tunable degradation behavior, suggesting that composites of both materials are suitable candidates as biomaterials for localized drug delivery into the human body. The combination of a pliable and soft polymeric material with a hard inorganic porous material of high drug loading capacity may engender improved control over degradation and drug release profiles and be beneficial for the preparation of advanced drug delivery devices and biodegradable implants or scaffolds. Materials & methods: In this work, three different pSi and PLLA composite formats were prepared. The first format involved grafting PLLA from pSi films via surface-initiated ring-opening polymerization (pSi–PLLA [grafted]). The second format involved spin coating a PLLA solution onto oxidized pSi films (pSi–PLLA [spin-coated]) and the third format consisted of a melt-cast PLLA monolith containing dispersed pSi microparticles (pSi–PLLA [monoliths]). The surface characterization of these composites was performed via infrared spectroscopy, scanning electron microscopy, atomic force microscopy and water contact angle measurements. The composite materials were loaded with a model cytotoxic drug, camptothecin (CPT). Drug release from the composites was monitored via fluorimetry and the release profiles of CPT showed distinct characteristics for each of the composites studied. Results: In some cases, controlled CPT release was observed for more than 5 days. The PLLA spin coat on pSi and the PLLA monolith containing pSi microparticles both released a CPT payload in accordance with the Higuchi and Ritger–Peppas release models. Composite materials were also brought into contact with human lens epithelial cells to determine the extent of cytotoxicity. Conclusion: We observed that all the CPT containing materials were highly efficient at releasing bioactive CPT, based on the cytotoxicity data.Support from the Australian Research Council (Australian Capital Territory, Australia), Bellberry Ltd. (Dulwich, South Australia), Flinders University (Adelaide, Australia) and the National Health and Medical Research Council (Canberra, Australia) is gratefully acknowledged

Porous silicon microparticles as an alternative support for solid phase DNA synthesis

Washington, US

Porous silicon microparticles as an alternative support for solid phase DNA synthesis

Washington, US

Characterisation of porous silicon/poly(L-lactide) composites prepared using surface initiated ring opening polymerisation

Bellingham, US

Development of a wireless intra-ocular pressure monitoring system for incorporation into a therapeutic glaucoma drainage implant

http://spiedigitallibrary.org/journals/doc/SPIEDL-home/proc

Effect of Amino-Functionalization on Insulin Delivery and Cell Viability for Two Types of Silica Mesoporous Structures

Inorganic Mesoporous Structures Are a Class of Novel Biomaterials that Have Shown Practical Applications in Delivery of a Variety of Therapeutic Agents. in the Present Study, Two Mesoporous Structures Were Prepared, and the Effect of Surface Modification on their Insulin Delivery and in Vitro Cytotoxicity Was Evaluated. Morphological and Structural Characterizations of Silica Particles Were Accomplished by Different Analytical Techniques, Including Scanning Electron Microscopy, X-Ray Diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) Surface Area Analyses. the Drug Loading Capacity and in Vitro Drug Release Behavior of Silica Structures Were Investigated under Simulated Gastrointestinal Conditions and Phosphate-Buffered Saline Solution using FTIR and UV–Vis Spectroscopy. in Vitro Cytotoxicity Evaluation Was Carried Out Via MTT Assay. Results Showed that the Morphology of MCM-41 Was Round, While SBA-15 Was Wheat Like, Both Possessed Almost Homogeneous Size Distribution. Also, Modification with Amine Did Not Influence the Morphology and Structure of the Particles. Both MCM-41 and SBA-15 Particles Were Found to Have Narrow Pore-Size Distributions of 2.8 and 6.8 Nm, Respectively. SBA-15 Particles Demonstrated a High Insulin Loading Capacity of About 15.1 %, While MCM-41 and Modified MCM-41 (MMCM-41) Were Observed to Load Virtually No Insulin at All. the Surface Modification by Amino Groups Resulted in Higher Insulin Loading and the Slower Rate of Release for Modified SBA-15 (MSBA-15) Compared to the Non-Modified SBA-15 (SBA-15). According to the Cytotoxicity Evaluation Results, All of the Samples Showed Cytotoxicity Grade 0–1, in a Concentration-Dependent Manner. Moreover, Insulin-Loaded MSBA-15 Particles Exhibited Higher Cell Viability Compared to the Others. It Was Concluded that Amine Modification of SBA-15 Could Result in Higher Loading and Extended Release of Insulin and More Cell Viability

A novel pressed porous silicon-polycaprolactone composite as a dual-purpose implant for the delivery of cells and drugs to the eye.

Author version made available in accordance with the Publisher's policy, after an embargo period of 12 months from the date of publication. © 2015. Licensed under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Dysfunction of corneal epithelial stem cells can result in painful and blinding disease of the ocular surface. In such cases, treatment may involve transfer of growth factor and normal adult stem cells to the ocular surface. Our purpose was to develop an implantable scaffold for the delivery of drugs and cells to the ocular surface. We examined the potential of novel composite biomaterials fabricated from electrospun polycaprolactone (PCL) fibres into which nanostructured porous silicon (pSi) microparticles of varying sizes (150-250 μm or <40 μm) had been pressed. The PCL fabric provided a flexible support for mammalian cells, whereas the embedded pSi provided a substantial surface area for efficient delivery of adsorbed drugs and growth factors. Measurements of tensile strength of these composites revealed that the pSi did not strongly influence the mechanical properties of the polymer microfiber component for the Si loadings evaluated. Human lens epithelial cells (SRA01/04) attached to the composite materials, and exhibited enhanced attachment and growth when the materials were coated with foetal bovine serum. To examine the ability of the materials to deliver a small-drug payload, pSi microparticles were loaded with fluorescein diacetate prior to cell attachment. After 6 hours (h), cells exhibited intracellular fluorescence, indicative of transfer of the fluorescein diacetate into viable cells and its subsequent enzymatic conversion to fluorescein. To investigate loading of large-molecule biologics, murine BALB/c 3T3 cells, responsive to epidermal growth factor, insulin and transferrin, were seeded on composite materials. The cells showed significantly more proliferation at 48 h when seeded on composites loaded with these biologics, than on unloaded composites. No cell proliferation was observed on PCL alone, indicating the biologics had loaded into the pSi microparticles. Drug release, measured by ELISA for insulin, indicated a burst followed by a slower, continuous release over six days. When implanted under the rat conjunctiva, the most promising composite material did not cause significant neovascularization but did elicit a macrophage and mild foreign body response. These novel pressed pSi-PCL materials have potential for delivery of both small and large drugs that can be released in active form, and can support the growth of mammalian cells

Designing superhydrophobic surfaces using fluorosilsesquioxane-urethane hybrid and porous silicon gradients

Bellingham, Washingto