Bioresorbable Materials on the Rise: From Electronic Components and Physical Sensors to In Vivo Monitoring Systems

Over the last decade, scientists have dreamed about the development of a bioresorbable technology that exploits a new class of electrical, optical, and sensing components able to operate in physiological conditions for a prescribed time and then disappear, being made of materials that fully dissolve in vivo with biologically benign byproducts upon external stimulation. The final goal is to engineer these components into transient implantable systems that directly interact with organs, tissues, and biofluids in real-time, retrieve clinical parameters, and provide therapeutic actions tailored to the disease and patient clinical evolution, and then biodegrade without the need for device-retrieving surgery that may cause tissue lesion or infection. Here, the major results achieved in bioresorbable technology are critically reviewed, with a bottom-up approach that starts from a rational analysis of dissolution chemistry and kinetics, and biocompatibility of bioresorbable materials, then moves to in vivo performance and stability of electrical and optical bioresorbable components, and eventually focuses on the integration of such components into bioresorbable systems for clinically relevant applications. Finally, the technology readiness levels (TRLs) achieved for the different bioresorbable devices and systems are assessed, hence the open challenges are analyzed and future directions for advancing the technology are envisaged

Template-Assisted Preparation of Micrometric Suspended Membrane Lattices of Photoluminescent and Non-Photoluminescent Polymers by Capillarity-Driven Solvent Evaporation: Application to Microtagging

In this work, the bottom-up template-assisted preparation of high-density lattices (up to 11 · 10(6) membranes/cm(2)) of suspended polymer membranes with micrometric size (in the order of few μm(2)) and sub-micrometric thickness (in the order of hundreds of nm) is demonstrated for both photoluminescent and non-photoluminescent polymers by capillarity-driven solvent evaporation. Solvent evaporation of low concentration polymer solutions drop-cast on an array of open-ended micropipes is shown to lead to polymer membrane formation at the inlet of the micropipes thanks to capillarity. The method is proven to be robust with high-yield (>98%) over large areas (1 cm(2)) and of general validity for both conjugated and non-conjugated polymers, e.g. poly(9,9-di-n-octylfluorene-alt-benzothiadiazole (F8BT), poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV), polystyrene (PS), thus breaking a new ground on the controlled preparation of polymer micro and nanostructures. Angle dependence and thermal stability of photoluminescence emission arising from F8BT membrane lattices was thorough investigated, highlighting a non-Lambertian photoluminescence emission of membrane lattices with respect to F8BT films. The method is eventually successfully applied to the preparation of both photoluminescent and non-photoluminescent micro Quick Response (μQR) codes using different polymers, i.e. F8BT, MDMO-PPV, PS, thus providing micrometric-sized taggants suitable for anti-counterfeiting applications

Nanoscale Photoluminescence Manipulation in Monolithic Porous Silicon Oxide Microcavity Coated with Rhodamine-Labeled Polyelectrolyte via Electrostatic Nanoassembling

Porous silicon (PSi) is a promising material for future integrated nanophotonics when coupled with guest emitters, still facing challenges in terms of homogenous distribution and nanometric thickness of the emitter coating within the silicon nanostructure. Herein, it is shown that the nanopore surface of a porous silicon oxide (PSiO2) microcavity (MC) can be conformally coated with a uniform nm-thick layer of a cationic light-emitting polyelectrolyte, e.g., poly(allylamine hydrochloride) labeled with Rhodamine B (PAH-RhoB), leveraging the self-tuned electrostatic interaction of the positively-charged PAH-RhoB polymer and negatively-charged PSiO2 surface. It is found that the emission of PAH-RhoB in the PSiO2 MC is enhanced (≈2.5×) and narrowed (≈30×) at the resonant wavelength, compared with that of PAH-RhoB in a non-resonant PSiO2 reference structure. The time-resolved photoluminescence analysis highlights a shortening (≈20%) of the PAH-RhoB emission lifetime in the PSiO2 MC at the resonance versus off-resonance wavelengths, and with respect to the reference structure, thereby proving a significant variation of the radiative decay rate. Remarkably, an experimental Purcell factor Fp = 2.82 is achieved. This is further confirmed by the enhancement of the photoluminescence quantum yield of the PAH-RhoB in the PSiO2 MC with respect to the reference structure. Application of the electrostatic nanoassembling approach to other emitting dyes, nanomaterials, and nanophotonic systems is envisaged

Robot assisted laparoscopic excision of a paraganglioma: new therapeutic approach

The Paraganglioma is the most common extra-adrenal pheochromocytoma arising from neural crest (1) (It will better to write: The paraganglioma is an extra-adrenal pheocromocytoma arising from the neural crest. 10% of pheocromocytomas are extra-adrenal and can arise form chromaffin tissue derived from primitive neuroectoderm). Minimally invasive techniques allow surgeons to perform the procedure without wide exposure and mobilization of intra abdominal organs. To our knowledge we present the third case of robotic excision of a retroperitoneal paraganglioma (2,3)

C-Si hybrid photonic structures by full infiltration of conjugated polymers into porous silicon rugate filters

Loading of one-dimensional (1-D) porous silicon photonic crystals (PS-PhCs), known as rugate filters, with luminescent materials is generally limited by the potential for (undesired) "pore clogging," in relation to the size of the nanoparticles (e.g. quantum dots) or molecular species, and so far mainly restricted to small molecular weight materials or small nanocrystals, or in situ polymerized dyes. Here we report the infiltration 1-D PS-PhCs with a green-emitting commercial luminescent polymer (F8BT, poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[ 2,1,3]thiadiazol-4,8-diyl)]), with a molecular weight of approximately 46 kDa across their whole depth (approximately 7.5 mu m), thereby showing that pore clogging is not a concern for these structures. We also characterize the modification of the photoluminescence (PL) and decay rates, and investigate the detailed inner morphology of the filters with the help of (scanning) transmission electron microscopy. We observe both suppression (in the stop-band) and enhancement (at the high-energy band-edge) of the PL. We also find that the photonic stop-band is red-shifted after polymer infiltration, due to the increased effective refractive index of the polymer-infiltrated nanostructured system. The presence of just one unbroadened peak in the reflectance spectra after infiltration confirms that infiltration extends for the whole depth of the rugate filters

Microwave-assisted in situ laser dye incorporation into high sensitivity whispering gallery mode microresonators

Optical whispering gallery mode microresonators (WGM-μRs) are powerful sensitive components with many analytical applications. Here, spherical WGM-μRs have been synthesised in a single-step microwave (MW)-assisted heterophase polymerisation. The microresonators are based on poly(styrene) beads into which the organic lasing dye nile red was incorporated as gain medium in situ during the polymerisation. The particle diameter and diameter distribution of the synthesised particles were tuned in the range of around 200 nm up to 50 μm by adjusting the concentration between stabiliser poly-(N-vinyl pyrrolidone) (PVP) and monomer styrene, and the solvent composition in the dispersion process. Lower water content enabled the synthesis of spherical particles with large size polydispersity, from which WGM-μRs with a variety of diameters were selected. Microspheres with diameters ≳3.5 μm supported WGMs. The WGMs were excited through free space via the fluorescence of the laser dye. Pumping power levels <1 μW were sufficient to excite WGMs. WGM shifts of beads with diameter between ≈5 and 30 μm measured in air and water show a sensitivity up to 54 nm/RIU for the smallest particles. Dye doped WGM-μR in the low μm size range obtained by the MW-assisted polymerisation process with its versatility, low processing times and high yields opens new horizons for the applications of these systems as sensors

Robot assisted laparoscopic excision of a paraganglioma: new therapeutic approach

The Paraganglioma is the most common extra-adrenal pheochromocytoma arising from neural crest (1) (It will better to write: The paraganglioma is an extra-adrenal pheocromocytoma arising from the neural crest. 10% of pheocromocytomas are extra-adrenal and can arise form chromaffin tissue derived from primitive neuroectoderm). Minimally invasive techniques allow surgeons to perform the procedure without wide exposure and mobilization of intra abdominal organs. To our knowledge we present the third case of robotic excision of a retroperitoneal paraganglioma (2,3)

C-Si hybrid photonic structures by full infiltration of conjugated polymers into porous silicon rugate filters

Loading of one-dimensional (1-D) porous silicon photonic crystals (PS-PhCs), known as rugate filters, with luminescent materials is generally limited by the potential for (undesired) “pore clogging,” in relation to the size of the nanoparticles (e.g. quantum dots) or molecular species, and so far mainly restricted to small molecular weight materials or small nanocrystals, or in situ polymerized dyes. Here we report the infiltration 1-D PS-PhCs with a green-emitting commercial luminescent polymer (F8BT, poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)]), with a molecular weight of approximately 46 kDa across their whole depth (approximately 7.5 μm), thereby showing that pore clogging is not a concern for these structures. We also characterize the modification of the photoluminescence (PL) and decay rates, and investigate the detailed inner morphology of the filters with the help of (scanning) transmission electron microscopy. We observe both suppression (in the stop-band) and enhancement (at the high-energy band-edge) of the PL. We also find that the photonic stop-band is red-shifted after polymer infiltration, due to the increased effective refractive index of the polymer-infiltrated nanostructured system. The presence of just one unbroadened peak in the reflectance spectra after infiltration confirms that infiltration extends for the whole depth of the rugate filters

Released micromachined beams utilizing laterally uniform porosity porous silicon

© 2014, Sun et al.; licensee Springer. Abstract: Suspended micromachined porous silicon beams with laterally uniform porosity are reported, which have been fabricated using standard photolithography processes designed for compatibility with complementary metal-oxide-semiconductor (CMOS) processes. Anodization, annealing, reactive ion etching, repeated photolithography, lift off and electropolishing processes were used to release patterned porous silicon microbeams on a Si substrate. This is the first time that micromachined, suspended PS microbeams have been demonstrated with laterally uniform porosity, well-defined anchors and flat surfaces. PACS: 81.16.-c; 81.16.Nd; 81.16.R