Porous Polymeric Nanofilms for Recreating the Basement Membrane in an Endothelial Barrier-on-Chip

Organs-on-chips (OoCs) support an organotypic human cell culture in vitro. Precise representation of basement membranes (BMs) is critical for mimicking physiological functions of tissue interfaces. Artificial membranes in polyester (PES) and polycarbonate (PC) commonly used in in vitro models and OoCs do not replicate the characteristics of the natural BMs, such as submicrometric thickness, selective permeability, and elasticity. This study introduces porous poly(d,l-lactic acid) (PDLLA) nanofilms for replicating BMs in in vitro models and demonstrates their integration into microfluidic chips. Using roll-to-roll gravure coating and polymer phase separation, we fabricated transparent ∼200 nm thick PDLLA films. These nanofilms are 60 times thinner and 27 times more elastic than PES membranes and show uniformly distributed pores of controlled diameter (0.4 to 1.6 μm), which favor cell compartmentalization and exchange of large water-soluble molecules. Human umbilical vein endothelial cells (HUVECs) on PDLLA nanofilms stretched across microchannels exhibited 97% viability, enhanced adhesion, and a higher proliferation rate compared to their performance on PES membranes and glass substrates. After 5 days of culture, HUVECs formed a functional barrier on suspended PDLLA nanofilms, confirmed by a more than 10-fold increase in transendothelial electrical resistance and blocked 150 kDa dextran diffusion. When integrated between two microfluidic channels and exposed to physiological shear stress, despite their ultrathin thickness, PDLLA nanofilms upheld their integrity and efficiently maintained separation of the channels. The successful formation of an adherent endothelium and the coculture of HUVECs and human astrocytes on either side of the suspended nanofilm validate it as an artificial BM for OoCs. Its submicrometric thickness guarantees intimate contact, a key feature to mimic the blood-brain barrier and to study paracrine signaling between the two cell types. In summary, porous PDLLA nanofilms hold the potential for improving the accuracy and physiological relevance of the OoC as in vitro models and drug discovery tools.

Review: Endometrial function in pregnancy establishment in cattle

The endometrium is fundamentally required for successful pregnancy in ruminants and species where the posthatching conceptus undergoes a protracted elongation and peri-implantation phase of pregnancy. Moreover, there are substantial waves of pregnancy loss during this pre- and peri-implantation period of pregnancy the precise source of which has not been clearly defined i.e., the maternal uterine contribution to this loss. Understanding the molecular interactions required for successful pregnancy in cattle will allow us to intervene to support pregnancy success during this vulnerable window. The endometrium contributes to most key developmental milestones of pregnancy establishment, including (1) contributing to the regulation of the oestrus cycle, (2) nourishing the preimplantation conceptus, (3) responding to the conceptus to create a more receptive microenvironment, (4) providing essential biophysical support, and (5) signalling and producing factors which affect the mother systemically. This review will summarise what we currently know about conceptus-maternal interactions as well as identify the gaps in our knowledge that could be filled with newer in vitro model approaches. These include the use of microfluidics, organ-on-a-chip devices, and bioinformatic approaches. This will help maximise food production efficiency (both meat and dairy) and decrease the environmental burden, while enhancing our understanding of the fundamental processes required for successful implantation in cattle.

Recreating cellular barriers in human microphysiological systems in-vitro

Within cellular barriers, cells are separated by basement membranes (BMs), nanometer-thick extracellular matrix layers. In existing in-vitro cellular-barrier models, cell-to-cell signaling can be preserved by culturing different cells in individual chambers separated by a semipermeable membrane. Their structure does not always replicate the BM thickness nor diffusion through it. Here, a porous polymeric nanofilm made of poly(D-L-lactic acid) (PDLLA) is proposed to recreate the BM in a microfluidic blood-brain-barrier model. Nanofilms showed an average thickness of [Formula: see text] and a maximum pore diameter of 1.6 μm. Human umbilical vein endothelial cells (HUVECs) were cultured on PDLLA. After 7 days, viability was >95% and cell morphology did not show relevant differences with HUVECs grown on control substrates. A protocol for suspending the nanofilm between 2 microfluidic chambers was identified and showed no leakage and good sealing. Clinical Relevance- Preclinical models of cellular barriers are a key step towards a deeper understanding of their roles in pathogenesis of various diseases: a physiologically relevant microfluidic model of the blood brain barrier (BBB) allows high-throughput investigations of BBB contribution in neurodegenerative diseases and cruelty-free screenings of drugs targeting the brain.

Leveraging bioengineering to assess cellular functions and communication within human fetal membranes

The fetal membranes enclose the growing fetus and amniotic fluid. Preterm prelabor rupture of fetal membranes is a leading cause of preterm birth. Fetal membranes are composed of many different cell types, both structural and immune. These cells must coordinate functions for tensile strength and membrane integrity to contain the growing fetus and amniotic fluid. They must also balance immune responses to pathogens with maintaining maternal-fetal tolerance. Perturbation of this equilibrium can lead to preterm premature rupture of membranes without labor. In this review, we describe the formation of the fetal membranes to orient the reader, discuss some of the common forms of communication between the cell types of the fetal membranes, and delve into the methods used to tease apart this paracrine signaling within the membranes, including emerging technologies such as organ-on-chip models of membrane immunobiology.

Embracing Mechanobiology in Next Generation Organ-On-A-Chip Models of Bone Metastasis

Bone metastasis in breast cancer is associated with high mortality. Biomechanical cues presented by the extracellular matrix play a vital role in driving cancer metastasis. The lack of in vitro models that recapitulate the mechanical aspects of the in vivo microenvironment hinders the development of novel targeted therapies. Organ-on-a-chip (OOAC) platforms have recently emerged as a new generation of in vitro models that can mimic cell-cell interactions, enable control over fluid flow and allow the introduction of mechanical cues. Biomaterials used within OOAC platforms can determine the physical microenvironment that cells reside in and affect their behavior, adhesion, and localization. Refining the design of OOAC platforms to recreate microenvironmental regulation of metastasis and probe cell-matrix interactions will advance our understanding of breast cancer metastasis and support the development of next-generation metastasis-on-a-chip platforms. In this mini-review, we discuss the role of mechanobiology on the behavior of breast cancer and bone-residing cells, summarize the current capabilities of OOAC platforms for modeling breast cancer metastasis to bone, and highlight design opportunities offered by the incorporation of mechanobiological cues in these platforms.

Probing morphological, genetic and metabolomic changes of in vitro embryo development in a microfluidic device

Assisted reproduction technologies for clinical and research purposes rely on a brief in vitro embryo culture which, despite decades of progress, remain suboptimal in comparison to the physiological environment. One promising tool to improve this technique is the development of bespoke microfluidic chambers. Here we present and validate a new microfluidic device in polydimethylsiloxane (PDMS) for the culture of early mouse embryos. Device material and design resulted embryo compatible and elicit minimal stress. Blastocyst formation, hatching, attachment and outgrowth formation on fibronectin-coated devices were similar to traditional microdrop methods. Total blastocyst cell number and allocation to the trophectoderm and inner cell mass lineages were unaffected. The devices were designed for culture of 10-12 embryos. Development rates, mitochondrial polarization and metabolic turnover of key energy substrates glucose, pyruvate and lactate were consistent with groups of 10 embryos in microdrop controls. Increasing group size to 40 embryos per device was associated with increased variation in development rates and altered metabolism. Device culture did not perturb blastocyst gene expression but did elicit changes in embryo metabolome, which can be ascribed to substrate leaching from PDMS and warrant further investigation.

Metabolomic Analysis Evidences That Uterine Epithelial Cells Enhance Blastocyst Development in a Microfluidic Device

Here we report the use of a microfluidic system to assess the differential metabolomics of murine embryos cultured with endometrial cells-conditioned media (CM). Groups of 10, 1-cell murine B6C3F1 × B6D2F1 embryos were cultured in the microfluidic device. To produce CM, mouse uterine epithelial cells were cultured in potassium simplex optimized medium (KSOM) for 24 h. Media samples were collected from devices after 5 days of culture with KSOM (control) and CM, analyzed by reverse phase liquid chromatography and untargeted positive ion mode mass spectrometry analysis. Blastocyst rates were significantly higher (p < 0.05) in CM (71.8%) compared to control media (54.6%). We observed significant upregulation of 341 compounds and downregulation of 214 compounds in spent media from CM devices when compared to control. Out of these, 353 compounds were identified showing a significant increased abundance of metabolites involved in key metabolic pathways (e.g., arginine, proline and pyrimidine metabolism) in the CM group, suggesting a beneficial effect of CM on embryo development. The metabolomic study carried out in a microfluidic environment confirms our hypothesis on the potential of uterine epithelial cells to enhance blastocyst development. Further investigations are required to highlight specific pathways involved in embryo development and implantation.

Translational Roadmap for the Organs-on-a-Chip Industry toward Broad Adoption

Organs-on-a-Chip (OOAC) is a disruptive technology with widely recognized potential to change the efficiency, effectiveness, and costs of the drug discovery process; to advance insights into human biology; to enable clinical research where human trials are not feasible. However, further development is needed for the successful adoption and acceptance of this technology. Areas for improvement include technological maturity, more robust validation of translational and predictive in vivo-like biology, and requirements of tighter quality standards for commercial viability. In this review, we reported on the consensus around existing challenges and necessary performance benchmarks that are required toward the broader adoption of OOACs in the next five years, and we defined a potential roadmap for future translational development of OOAC technology. We provided a clear snapshot of the current developmental stage of OOAC commercialization, including existing platforms, ancillary technologies, and tools required for the use of OOAC devices, and analyze their technology readiness levels. Using data gathered from OOAC developers and end-users, we identified prevalent challenges faced by the community, strategic trends and requirements driving OOAC technology development, and existing technological bottlenecks that could be outsourced or leveraged by active collaborations with academia.

Polylactic is a Sustainable, Low Absorption, Low Autofluorescence Alternative to Other Plastics for Microfluidic and Organ-on-Chip Applications

Organ-on-chip (OOC) devices are miniaturized devices replacing animal models in drug discovery and toxicology studies. The majority of OOC devices are made from polydimethylsiloxane (PDMS), an elastomer widely used in microfluidic prototyping, but posing a number of challenges to experimentalists, including leaching of uncured oligomers and uncontrolled absorption of small compounds. Here we assess the suitability of polylactic acid (PLA) as a replacement material to PDMS for microfluidic cell culture and OOC applications. We changed the wettability of PLA substrates and demonstrated the functionalization method to be stable over a time period of at least 9 months. We successfully cultured human cells on PLA substrates and devices, without coating. We demonstrated that PLA does not absorb small molecules, is transparent (92% transparency), and has low autofluorescence. As a proof of concept of its manufacturability, biocompatibility, and transparency, we performed a cell tracking experiment of prostate cancer cells in a PLA device for advanced cell culture.

Potential of Manuka Honey as a Natural Polyelectrolyte to Develop Biomimetic Nanostructured Meshes With Antimicrobial Properties

The use of antibiotics has been the cornerstone to prevent bacterial infections; however, the emergency of antibiotic-resistant bacteria is still an open challenge. This work aimed to develop a delivery system for treating soft tissue infections for: (1) reducing the released antimicrobial amount, preventing drug-related systemic side effects; (2) rediscovering the beneficial effects of naturally derived agents; and (3) preserving the substrate functional properties. For the first time, Manuka honey (MH) was proposed as polyelectrolyte within the layer-by-layer assembly. Biomimetic electrospun poly(ε-caprolactone) meshes were treated via layer-by-layer assembly to obtain a multilayered nanocoating, consisting of MH as polyanion and poly-(allylamine-hydrochloride) as polycation. Physicochemical characterization demonstrated the successful nanocoating formation. Different cell lines (human immortalized and primary skin fibroblasts, and primary endothelial cells) confirmed positively the membranes cytocompatibility, while bacterial tests using Gram-negative and Gram-positive bacteria demonstrated that the antimicrobial MH activity was dependent on the concentration used and strains tested.

Remote heart rate monitoring - Assessment of the Facereader rPPg by Noldus

Remote photoplethysmography (rPPG) allows contactless monitoring of human cardiac activity through a video camera. In this study, we assessed the accuracy and precision for heart rate measurements of the only consumer product available on the market, namely the FacereaderTM rPPG by Noldus, with respect to a gold standard electrocardiograph. Twenty-four healthy participants were asked to sit in front of a computer screen and alternate two periods of rest with two stress tests (i.e. Go/No-Go task), while their heart rate was simultaneously acquired for 20 minutes using the ECG criterion measure and the FacereaderTM rPPG. Results show that the FacereaderTM rPPG tends to overestimate lower heart rates and underestimate higher heart rates compared to the ECG. The Facereader™ rPPG revealed a mean bias of 9.8 bpm, the 95% limits of agreement (LoA) ranged from almost -30 up to +50 bpm. These results suggest that whilst the rPPG FacereaderTM technology has potential for contactless heart rate monitoring, its predictions are inaccurate for higher heart rates, with unacceptable precision across the entire range, rendering its estimates unreliable for monitoring individuals.

Organs-On-Chip Models of the Female Reproductive System

Microfluidic-based technology attracts great interest in cell biology and medicine, in virtue of the ability to better mimic the in vivo cell microenvironment compared to conventional macroscale cell culture platforms. Recent Organs-on-chip (OoC) models allow to reproduce in vitro tissue and organ-level functions of living organs and systems. These models have been applied for the study of specific functions of the female reproductive tract, which is composed of several organs interconnected through intricate endocrine pathways and communication mechanisms. To date, a disease and toxicology study of this system has been difficult to perform. Thus, there is a compelling need to develop innovative platforms for the generation of disease model and for performing drug toxicity/screening in vitro studies. This review is focused on the analysis of recently published OoC models that recreate pathological and physiological characteristics of the female reproductive organs and tissues. These models aim to be used to assess changes in metabolic activity of the specific cell types and the effect of exposure to hormonal treatment or chemical substances on some aspects of reproduction and fertility. We examined these models in terms of device specifications, operating procedures, accuracy for studying the biochemical and functional activity of living tissues and the paracrine signalling that occurs within the different tissues. These models represent a powerful tool for understanding important diseases and syndromes affecting women all around the world. Immediate adoption of these models will allow to clarify diseases, causes and adverse events occurring during pregnancy such as pre-eclampsia, infertility or preterm birth, endometriosis and infertility.

Mouse embryo assay to evaluate polydimethylsiloxane (PDMS) embryo-toxicity

In vitro embryo culture to support In Vitro Fertilization (IVF) procedures is a well-established but still critical technique. In the last decade first attempts to use microfluidic devices in IVF have shown positive results, enabling to control the culture conditions and to preserve the quality of the embryos during their development. In this study we completed an industry standard mouse embryo assay (MEA) to exclude potential toxic effects of PDMS.

Instrumenting a Fetal Membrane on a Chip as Emerging Technology for Preterm Birth Research

Preterm birth (PTB) is clinically defined as process of giving birth before 37 weeks of gestation and is a leading cause of death among neonates and children under the age of five. Prematurity remains a critical issue in developed countries, yet our understanding of the pathophysiology of PTB remains largely unknown. Among pregnancy complications, subclinical infections such as chorioamnionitis (CAM) are implicated in up to 70% of PTB cases. Specifically, CAM is characterized by the infection of the fetal membranes that surround the developing fetus and extend from the placenta, and is often associated with preterm, premature rupture of the fetal membranes (PPROM). The fetal membrane plays a key structural role in maintaining the fetal and maternal compartments of the gravid uterus. However, our understanding of the mechanisms of PPROM and the spatio-temporal progress of CAM remains vastly unknown. A lack of human-derived models have hindered our understanding of the mechanism that govern spontaneous PTB. Thus, in this short review, we discuss the emerging microfabrication technologies, specifically, organ-on-chip (OoCs) models, that seek to recapitulate the cellular and molecular context of the gestational membranes in vitro. These models show promise to facilitate the investigation of pathologic mechanisms that drive these disease conditions by mimicking the interactive contribution of the major cell types that make up the microenvironment of the fetal membrane and enable high throughput screening. Herein, we histologically characterize the microenvironment of the fetal membrane as a metric for scaling to recapitulate the functional components of the human fetal membrane. We review the current OoC models of the gravid uterus and conceptualize an "Instrumented Fetal Membrane on a Chip" (IFMOC) design as a prototype for PPROM and CAM research. Lastly, we discuss further applications of these OoC models for toxicological or pharmacological screening and personalized medicine. Fetal membrane OoCs offer an innovative and valuable platform to explore complex interactions between multiple drug types, toxic substances, and/or pathogenic microbes and their potential impacts on pregnancy outcomes. Further work will be required by integrating technological and analytical capabilities in order to characterize the fetal membrane microenvironment for preterm birth research.

Assessment of the Fitbit Charge 2 for monitoring heart rate

Fitness trackers are devices or applications for monitoring and tracking fitness-related metrics such as distance walked or run, calorie consumption, quality of sleep and heart rate. Since accurate heart rate monitoring is essential in fitness training, the objective of this study was to assess the accuracy and precision of the Fitbit Charge 2 for measuring heart rate with respect to a gold standard electrocardiograph. Fifteen healthy participants were asked to ride a stationary bike for 10 minutes and their heart rate was simultaneously recorded from each device. Results showed that the Fitbit Charge 2 underestimates the heart rate. Although the mean bias in measuring heart rate was a modest -5.9 bpm (95% CI: -6.1 to -5.6 bpm), the limits of agreement, which indicate the precision of individual measurements, between the Fitbit Charge 2 and criterion measure were wide (+16.8 to -28.5 bpm) indicating that an individual heart rate measure could plausibly be underestimated by almost 30 bpm.

Optimization of electrospun fibrous membranes for in vitro modeling of blood-brain barrier

The blood-brain barrier (BBB) plays a critical role in brain homeostasis at the cellular and global level. Mimicking the selective permeability and transport properties of the BBB to specific molecules and cells remains a significant challenge towards the development of a physiologically relevant in vitro BBB model. In this study, we developed electrospun poly (ε-caprolactone) (PCL) and polyethylene glycol (PEG) copolymer membranes that supported different cellular components of the neurovascular unit including human-derived endothelial cells, pericytes and astrocytes. Comparative analyses of thickness, morphology, biocompatibility and permeability of membranes were also conducted. We found that collagen coated 4%PEG-96%PCL membranes supported the growth of a confluent and tight endothelium confirmed by transendothelial electrical resistance measurements (TEER). Based on fabrication process and reported results, we finally discuss the adoption of these electrospun fiber membranes for in vitro and on-a-chip human BBB models.

Ultrathin Polymer Membranes with Patterned, Micrometric Pores for Organs-on-Chips

The basal lamina or basement membrane (BM) is a key physiological system that participates in physicochemical signaling between tissue types. Its formation and function are essential in tissue maintenance, growth, angiogenesis, disease progression, and immunology. In vitro models of the BM (e.g., Boyden and transwell chambers) are common in cell biology and lab-on-a-chip devices where cells require apical and basolateral polarization. Extravasation, intravasation, membrane transport of chemokines, cytokines, chemotaxis of cells, and other key functions are routinely studied in these models. The goal of the present study was to integrate a semipermeable ultrathin polymer membrane with precisely positioned pores of 2 μm diameter in a microfluidic device with apical and basolateral chambers. We selected poly(l-lactic acid) (PLLA), a transparent biocompatible polymer, to prepare the semipermeable ultrathin membranes. The pores were generated by pattern transfer using a three-step method coupling femtosecond laser machining, polymer replication, and spin coating. Each step of the fabrication process was characterized by scanning electron microscopy to investigate reliability of the process and fidelity of pattern transfer. In order to evaluate the compatibility of the fabrication method with organs-on-a-chip technology, porous PLLA membranes were embedded in polydimethylsiloxane (PDMS) microfluidic devices and used to grow human umbilical vein endothelial cells (HUVECS) on top of the membrane with perfusion through the basolateral chamber. Viability of cells, optical transparency of membranes and strong adhesion of PLLA to PDMS were observed, thus confirming the suitability of the prepared membranes for use in organs-on-a-chip devices.

Exposure to the environmental endocrine disruptor TCDD and human reproductive dysfunction: Translating lessons from murine models

Humans and other animals are exposed to a wide array of man-made toxicants, many of which act as endocrine disruptors that exhibit differential effects across the lifespan. In humans, while the impact of adult exposure is known for some compounds, the potential consequences of developmental exposure to endocrine disrupting chemicals (EDCs) is more difficult to ascertain. Animal studies have revealed that exposure to EDCs prior to puberty can lead to adult reproductive disease and dysfunction. Specifically, in adult female mice with an early life exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), we demonstrated a transgenerational occurrence of several reproductive diseases that have been linked to endometriosis in women. Herein, we review the evidence for TCDD-associated development of adult reproductive disease as well as known epigenetic alterations associated with TCDD and/or endometriosis. We will also introduce new "Organ-on-Chip" models which, combined with our established murine model, are expected to further enhance our ability to examine alterations in gene-environment interactions that lead to heritable disease.

Recreating blood-brain barrier physiology and structure on chip: A novel neurovascular microfluidic bioreactor

The blood-brain barrier (BBB) is a critical structure that serves as the gatekeeper between the central nervous system and the rest of the body. It is the responsibility of the BBB to facilitate the entry of required nutrients into the brain and to exclude potentially harmful compounds; however, this complex structure has remained difficult to model faithfully in vitro. Accurate in vitro models are necessary for understanding how the BBB forms and functions, as well as for evaluating drug and toxin penetration across the barrier. Many previous models have failed to support all the cell types involved in the BBB formation and/or lacked the flow-created shear forces needed for mature tight junction formation. To address these issues and to help establish a more faithful in vitro model of the BBB, we have designed and fabricated a microfluidic device that is comprised of both a vascular chamber and a brain chamber separated by a porous membrane. This design allows for cell-to-cell communication between endothelial cells, astrocytes, and pericytes and independent perfusion of both compartments separated by the membrane. This NeuroVascular Unit (NVU) represents approximately one-millionth of the human brain, and hence, has sufficient cell mass to support a breadth of analytical measurements. The NVU has been validated with both fluorescein isothiocyanate (FITC)-dextran diffusion and transendothelial electrical resistance. The NVU has enabled in vitro modeling of the BBB using all human cell types and sampling effluent from both sides of the barrier.

Neurovascular unit on a chip: implications for translational applications

The blood-brain barrier (BBB) dynamically controls exchange between the brain and the body, but this interaction cannot be studied directly in the intact human brain or sufficiently represented by animal models. Most existing in vitro BBB models do not include neurons and glia with other BBB elements and do not adequately predict drug efficacy and toxicity. Under the National Institutes of Health Microtissue Initiative, we are developing a three-dimensional, multicompartment, organotypic microphysiological system representative of a neurovascular unit of the brain. The neurovascular unit system will serve as a model to study interactions between the central nervous system neurons and the cerebral spinal fluid (CSF) compartment, all coupled to a realistic blood-surrogate supply and venous return system that also incorporates circulating immune cells and the choroid plexus. Hence all three critical brain barriers will be recapitulated: blood-brain, brain-CSF, and blood-CSF. Primary and stem cell-derived human cells will interact with a variety of agents to produce critical chemical communications across the BBB and between brain regions. Cytomegalovirus, a common herpesvirus, will be used as an initial model of infections regulated by the BBB. This novel technological platform, which combines innovative microfluidics, cell culture, analytical instruments, bioinformatics, control theory, neuroscience, and drug discovery, will replicate chemical communication, molecular trafficking, and inflammation in the brain. The platform will enable targeted and clinically relevant nutritional and pharmacologic interventions for or prevention of such chronic diseases as obesity and acute injury such as stroke, and will uncover potential adverse effects of drugs. If successful, this project will produce clinically useful technologies and reveal new insights into how the brain receives, modifies, and is affected by drugs, other neurotropic agents, and diseases.

Flexible polymeric ultrathin film for mesenchymal stem cell differentiation

Ultrathin films (also called nanofilms) are two-dimensional (2-D) polymeric structures with potential application in biology, biotechnology, cosmetics and tissue engineering. Since they can be handled in liquid form with micropipettes or tweezers they have been proposed as flexible systems for cell adhesion and proliferation. In particular, with the aim of designing a novel patch for bone or tendon repair and healing, in this work the biocompatibility, adhesion and proliferation activity of Saos-2, MRC-5 and human and rat mesenchymal stem cells on poly(lactic acid) nanofilms were evaluated. The nanofilms did not impair the growth and differentiation of osteoblasts and chondrocytes. Moreover, nanofilm adhesion to rabbit joints was evident under ex vivo conditions.

Free-standing poly(L-lactic acid) nanofilms loaded with superparamagnetic nanoparticles

Freely suspended nanocomposite thin films based on soft polymers and functional nanostructures have been widely investigated for their potential application as active elements in microdevices. However, most studies are focused on the preparation of nanofilms composed of polyelectrolytes and charged colloidal particles. Here, a new technique for the preparation of poly(l-lactic acid) free-standing nanofilms embeddidng superparamagnetic iron oxide nanoparticles is presented. The fabrication process, based on a spin-coating deposition approach, is described, and the influence of each production parameter on the morphology and magnetic properties of the final structure is investigated. Superparamagnetic free-standing nanofilms were obtained, as evidenced by a magnetization hysteresis measurement performed with a superconducting quantum interference device (SQUID). Nanofilm surface morphology and thickness were evaluated by atomic force microscopy (AFM), and the nanoparticle dispersion inside the composites was investigated by transmission electron microscopy (TEM). These nanofilms, composed of a biodegradable polyester and remotely controllable by external magnetic fields, are promising candidates for many potential applications in the biomedical field.

From miniature to nano robots for diagnostic and therapeutic applications

This paper presents the evolution of diagnostic and therapeutic procedures as a process of convergence of technologies coming from different fields and involving different disciplines. In particular, it illustrates how modern surgery evolved thanks to fundamental biology knowledge; thus, with the introduction of imaging techniques intra-operatively and with the introduction of robotics, surgical procedures became much more predictable, precise and effective. Finally, the recent developments of optics (with CMOS and CCD technologies, and with the introduction of fiber optic technologies) allowed to "see" inside the human body, thus reducing the invasiveness of surgical procedures and making diagnostic procedures adequate for an effective early discovery of pathologies. Nowadays, we are assisting to a concrete merging between microrobotics technologies and bioengineering, with the potential to bring therapeutic tools where requested and when requested, with high precision and with very limited side effects. Furthermore, nanotechnology offers the possibility to fully implement this merging, thanks to the development of dedicated theranostic nanotools suitably fitting the considered convergence scenario.

A pilot study on a new anchoring mechanism for surgical applications based on mucoadhesives

In order to minimize the invasiveness of laparoscopic surgery, different techniques are emerging from research to clinical practice. Whether the incision is performed on the outside - as in Single Port Laparoscopy (SPL) - or on the inside - as in Natural Orifice Transluminal Endoscopic Surgery (NOTES) - of the patient's body, inserting and operating all the instruments from a single access site seems to be the next challenge in surgery. Magnetic guidance has been recently proposed for controlling surgical tools deployed from a single access. However, the exponential drop of magnetic field with distance makes this solution suitable only for the upper side of the abdominal cavity in nonobese patients. In the present paper we introduce a polymeric anchoring mechanism to lock surgical assistive tools inside the gastric cavity, based on the use of mucoadhesive films. Mucoadhesive properties of four formulations, with different chemical components and concentration, are evaluated by using both in vitro and ex vivo test benches on porcine stomach samples. Hydration of mucoadhesive films by contact with the aqueous mucous layer is analyzed by means of in vitro swelling tests, whereas optimal preloading conditions and adhesion performances, in terms of detachment force, supported weight and size are investigated ex vivo. Mucoadhesion is observed with all the four formulations. For a contact area of 113 mm(2), the maximum normal and shear detachment forces withstood by the adhesive film are 2,6 N and 1 N respectively. These values grow up to 12,14 N and 4,5 N when the contact area increases to 706 mm(2). Lifetime of the bonding on the inner side of the stomach wall was around two hours. Mucoadhesive anchoring represents a fully biocompatible and safe approach to deploy multiple assistive surgical tools on mucosal tissues by minimizing the number of access ports. This technique has been quantitatively assessed ex vivo for anchoring on the inner wall of the gastric cavity or in gastroscopic surgery. By properly varying the chemical formulation, this approach can be extended to other cavities of the human body.

Magnetic Nanofilms for Biomedical Applications

Polymeric ultrathin films, also called nanofilms or nanosheets, show peculiar properties making them potentially useful for several applications in biomedicine, e.g., as nanoplasters for localized drug release or as a new solution for closing endoluminal surgical wounds. In this sense, one of most challenging issues is film control in the working environment: the possibility of including magnetic components, such as magnetic nanoparticles or nanotubes, paves the way for the effective use of nanofilms in the human body, by allowing precise positioning by an external magnetic field. State of the art and new perspectives of magnetic nanofilms for biomedical applications are here presented, including fabrication, modeling, characterization and validation.

Cell creeping and controlled migration by magnetic carbon nanotubes

Carbon nanotubes (CNTs) are tubular nanostructures that exhibit magnetic properties due to the metal catalyst impurities entrapped at their extremities during fabrication. When mammalian cells are cultured in a CNT-containing medium, the nanotubes interact with the cells, as a result of which, on exposure to a magnetic field, they are able to move cells towards the magnetic source. In the present paper, we report on a model that describes the dynamics of this mammalian cell movement in a magnetic field consequent on CNT attachment. The model is based on Bell's theory of unbinding dynamics of receptor-ligand bonds modified and validated by experimental data of the movement dynamics of mammalian cells cultured with nanotubes and exposed to a magnetic field, generated by a permanent magnet, in the vicinity of the cell culture wells. We demonstrate that when the applied magnetic force is below a critical value (about Fc ≈ 10-11 N), the cell 'creeps' very slowly on the culture dish at a very low velocity (10-20 nm/s) but becomes detached from the substrate when this critical magnetic force is exceeded and then move towards the magnetic source.

Neuroblastoma cells displacement by magnetic carbon nanotubes

In this paper, as-produced multiwall carbon nanotubes (MWNTs) have been analyzed by scanning electron microscopy and energy dispersive X-ray spectrometry, revealing the presence of Fe, Al, and Zn residuals and impurities. MWNTs have then been dispersed in Pluronic F127 aqueous solution and used to seed neuroblastoma cell lines (HN9.10e and SH-SY5Y) for three days. We found that MWNTs interact with cells and induce, under a permanent constant magnetic field, the cell displacement toward the magnetic source.

Investigation of CNTs interaction with fibroblast cells

The need for toxicological studies on carbon nanotubes (CNTs) has arisen from the rapidly emerging applications of CNTs well beyond material science and engineering. In order to provide a method to collect data about toxicology, we characterized by Scanning Electron Microscopy (SEM), by Energy Dispersive X-ray Spectrometry (EDS) analysis and by Focused Ion Beam (FIB) microscopy different kinds of treated CNTs. The bio-interaction was investigated seeding Crandell feline kidney fibroblasts with CNT-modified medium; a dedicated sample preparation by FIB has been defined to fix cells. In the present study, the cytotoxic effects of CNTs with 91% and 97% of purity were compared and changes in the growth behaviour of cells after 3 days in culture with modified medium have been recorded, considering also the distribution of CNTs within cells. While lower purified CNTs induced a slight cytotoxic effect, homogeneously suspended CNTs with high purity were less cytotoxic, and the rate of cell growth remained constant. CNTs aggregated in bundles, showed high adhesion on cell membrane. Interestingly, CNTs bundles were observed inside cells, underneath the cell membrane, and despite of that, cells were extended, in good vitality conditions and no cell-degeneration was observed.

Design criteria of neuron/electrode interface. The focused ion beam technology as an analytical method to investigate the effect of electrode surface morphology on neurocompatibility

"Neurocompatibility" is a broad definition which comprises aspects of biocompatibility, chemical and physical surface properties, and biostability of an artificial substrate interfaced with a neural tissue. The main issue coming from the analysis of the state of art of neuroprosthesis and neuron/electrode interfaces is the strong influence of electrode surface morphology on neurocompatibility. Enhanced functions of neurons have been observed on nano-structured materials. This paper proposes the use of focused ion beam (FIB) technology as high precision machining technique to modify the surface morphology of an interface material. By controlling the ion milling in three dimensions, the fabrication of a surface with any predefined morphology becomes possible with nanometric precision. In vitro tests on PC12 cells cultured on surfaces with different morphologies show that the surface morphology influences the cell adhesion. Experimental results suggest an enhancement of the interaction between cells and artificial surfaces at a specific scale (tens of nanometres) which is the typical scale of cellular interaction in the extra-cellular matrix (ECM) of living organisms.

Intracerebral hematoma following evacuation of chronic subdural hematomas. Report of two cases

Two cases of intracerebral hemorrhage occurring after evacuation of bilateral chronic subdural hematomas are reported. Possible pathogenic mechanisms included hemorrhage into previously undetected areas of contusion, damage to cerebral vasculature secondary to rapid perioperative parenchymal shift, and sudden increase in cerebral blood flow combined with focal disruption of autoregulation; of these, the latter mechanism seemed most likely to be responsible for the hematoma formation. The need for clinical awareness of this nearly uniformly devastating complication, as well as prompt use of computerized tomography scanning in assessing the postoperative course, are stressed.