Self-assembled materials and supramolecular chemistry within microfluidic environments: from common thermodynamic states to non-equilibrium structures.

Self-assembly is a crucial component in the bottom-up fabrication of hierarchical supramolecular structures and advanced functional materials. Control has traditionally relied on the use of encoded building blocks bearing suitable moieties for recognition and interaction, with targeting of the thermodynamic equilibrium state. On the other hand, nature leverages the control of reaction-diffusion processes to create hierarchically organized materials with surprisingly complex biological functions. Indeed, under non-equilibrium conditions (kinetic control), the spatio-temporal command of chemical gradients and reactant mixing during self-assembly (the creation of non-uniform chemical environments for example) can strongly affect the outcome of the self-assembly process. This directly enables a precise control over material properties and functions. In this tutorial review, we show how the unique physical conditions offered by microfluidic technologies can be advantageously used to control the self-assembly of materials and of supramolecular aggregates in solution, making possible the isolation of intermediate states and unprecedented non-equilibrium structures, as well as the emergence of novel functions. Selected examples from the literature will be used to confirm that microfluidic devices are an invaluable toolbox technology for unveiling, understanding and steering self-assembly pathways to desired structures, properties and functions, as well as advanced processing tools for device fabrication and integration.

An imported case of acute pulmonary coccidioidomycosis in an Italian traveller.

Coccidioidomycosis is a fungal infection caused by the Coccidioides species, which is endemic in the deserts of the southwestern region of the United States, northern Mexico, and in some areas of Central and South America. We describe a case of pulmonary coccidioidomycosis in a 49-year-old Italian man who came to our hospital with fever and joint and muscle pain 10 days after his return to Italy from Venezuela. Computer Tomography revealed multiple bilateral pulmonary nodules with mediastinal lymphadenopathy. Pulmonary coccidioidomycosis was diagnosed by a serological test, and fluconazole was immediately started. The patient improved within 2 weeks, with complete clinical recovery after 6 months of therapy. This case appears to be part of a large serologically unconfirmed outbreak. In order to provide early diagnosis and treatment, healthcare providers should be aware of coccidioidomycosis, even in travellers returning home from short trips to endemic areas.

Exploring nasopharyngeal microbiota profile in children affected by SARS-CoV-2 infection.

The relationship between COVID-19 and nasopharyngeal (NP) microbiota has been investigated mainly in the adult population. We explored the NP profile of children affected by COVID-19, compared to healthy controls (CTRLs). NP swabs of children with COVID-19, collected between March and September 2020, were investigated at the admission (T0), 72 h to 7 days (T1), and at the discharge (T2) of the patients. NP microbiota was analyzed by 16S rRNA targeted-metagenomics. Data from sequencing were investigated by QIIME 2.0 and PICRUSt 2. Multiple machine learning (ML) models were exploited to classify patients compared to CTRLs. The NP microbiota of COVID-19 patients (N = 71) was characterized by reduction of α-diversity compared to CTRLs (N = 59). The NP microbiota of COVID-19 cohort appeared significantly enriched in Streptococcus, Haemophilus, Staphylococcus, Veillonella, Enterococcus, Neisseria, Moraxella, Enterobacteriaceae, Gemella, Bacillus, and reduced in Faecalibacterium, Akkermansia, Blautia, Bifidobacterium, Ruminococcus, and Bacteroides, compared to CTRLs (FDR < 0.001). Exploiting ML models, Enterococcus, Pseudomonas, Streptococcus, Capnocytopagha, Tepidiphilus, Porphyromonas, Staphylococcus, and Veillonella resulted as NP microbiota biomarkers, in COVID-19 patients. No statistically significant differences were found comparing the NP microbiota profile of COVID-19 patients during the time-points or grouping patients on the basis of high, medium, and low viral load (VL). This evidence provides specific pathobiont signatures of the NP microbiota in pediatric COVID-19 patients, and the reduction of anaerobic protective commensals. Our data suggest that the NP microbiota may have a specific disease-related signature since infection onset without changes during disease progression, regardless of the SARS-CoV-2 VL. IMPORTANCE: Since the beginning of pandemic, we know that children are less susceptible to severe COVID-19 disease. A potential role of the nasopharyngeal (NP) microbiota has been hypothesized but to date, most of the studies have been focused on adults. We studied the NP microbiota modifications in children affected by SARS-CoV-2 infection showing a specific NP microbiome profile, mainly composed by pathobionts and almost missing protective anaerobic commensals. Moreover, in our study, specific microbial signatures appear since the first days of infection independently from SARS-CoV-2 viral load.

Contrast-enhanced ultrasound tracking of helical propellers with acoustic phase analysis and comparison with color Doppler.

Medical microrobots (MRs) hold the potential to radically transform several interventional procedures. However, to guarantee therapy success when operating in hard-to-reach body districts, a precise and robust imaging strategy is required for monitoring and controlling MRs in real-time. Ultrasound (US) may represent a powerful technology, but MRs' visibility with US needs to be improved, especially when targeting echogenic tissues. In this context, motions of MRs have been exploited to enhance their contrast, e.g., by Doppler imaging. To exploit a more selective contrast-enhancement mechanism, in this study, we analyze in detail the characteristic motions of one of the most widely adopted MR concepts, i.e., the helical propeller, with a particular focus on its interactions with the backscattered US waves. We combine a kinematic analysis of the propeller 3D motion with an US acoustic phase analysis (APA) performed on the raw radio frequency US data in order to improve imaging and tracking in bio-mimicking environments. We validated our US-APA approach in diverse scenarios, aimed at simulating realistic in vivo conditions, and compared the results to those obtained with standard US Doppler. Overall, our technique provided a precise and stable feedback to visualize and track helical propellers in echogenic tissues (chicken breast), tissue-mimicking phantoms with bifurcated lumina, and in the presence of different motion disturbances (e.g., physiological flows and tissue motions), where standard Doppler showed poor performance. Furthermore, the proposed US-APA technique allowed for real-time estimation of MR velocity, where standard Doppler failed.

Erratum: Publisher's Note: "Contrast-enhanced ultrasound tracking of helical propellers with acoustic phase analysis and comparison with color Doppler" [APL Bioeng. 6, 036102 (2022)].

[This corrects the article DOI: 10.1063/5.0097145.].

Structural and magnetic characterization of batch-fabricated nickel encapsulated multi-walled carbon nanotubes.

We report on the growth and fabrication of Ni-filled multi-walled carbon nanotubes (Ni-MWNTs) with an average diameter of 115 nm and variable length of 400 nm-1 µm. The Ni-MWNTs were grown using template-assisted electrodeposition and low pressure chemical vapor deposition (LPCVD) techniques. Anodized alumina oxide (AAO) templates were fabricated on Si using a current controlled process. This was followed by the electrodeposition of Ni nanowires (NWs) using galvanostatic pulsed current (PC) electrodeposition. Ni NWs served as the catalyst to grow Ni-MWNTs in an atmosphere of H2/C2H2 at a temperature of 700 °C. Time dependent depositions were carried out to understand the diffusion and growth mechanism of Ni-MWNTs. Characterization was carried out using scanning electron microscopy (SEM), focused ion beam (FIB) milling, transmission electron microscopy (TEM), Raman spectroscopy and energy dispersive x-ray spectroscopy (EDX). TEM analysis revealed that the Ni nanowires possess a fcc structure. To understand the effects of the electrodeposition parameters, and also the effects of the high temperatures encountered during MWNT growth on the magnetic properties of the Ni-MWNTs, vibrating sample magnetometer (VSM) measurements were performed. The template-based fabrication method is repeatable, efficient, enables batch fabrication and provides good control on the dimensions of the Ni-MWNTs.

Accidental Nasal Myiasis Caused by Megaselia rufipes (Diptera: Phoridae) in a Child.

A case of a nasal myiasis in a 3-yr-old Italian girl who was referred to Bambino Gesù Hospital in Rome, Italy, is reported. Larvae discharged with the nasal mucus were microscopically identified as Megaselia spp.; DNA barcoding analysis showed that they belonged to the 'scuttle fly' species Megaselia rufipes (Meigen). Based on the patient's history, she became infected when she played outside. This is the first report of myiasis in humans due to M. rufipes (Diptera: Phoridae).

Mechanically interlocked 3D multi-material micromachines.

Metals and polymers are dissimilar materials in terms of their physicochemical properties, but complementary in terms of functionality. As a result, metal-organic structures can introduce a wealth of novel applications in small-scale robotics. However, current fabrication techniques are unable to process three-dimensional metallic and polymeric components. Here, we show that hybrid microstructures can be interlocked by combining 3D lithography, mold casting, and electrodeposition. Our method can be used to achieve complex multi-material microdevices with unprecedented resolution and topological complexity. We show that metallic components can be combined with structures made of different classes of polymers. Properties of both metals and polymers can be exploited in parallel, resulting in structures with high magnetic responsiveness, elevated drug loading capacity, on-demand shape transformation, and elastic behavior. We showcase the advantages of our approach by demonstrating new microrobotic locomotion modes and controlled agglomeration of swarms.

Mechanical evaluation of new injection needles for dental anesthesia.

AIM: In this study Authors want to evaluate the static and dynamic flexural behaviour of innovative injection needles for dental anaesthesia comparing to the traditional needles. METHODS: Four kinds of innovative injection needles (Carpule Free Flow-Heraeus Kulzer), different for length and external diameter, have been evaluated in comparison with the traditional ones (Carpule-Heraeus Kulzer), dimensions being equal except for the internal diameter. Static stiffness tests (10 for each kind of needles, resulting in a totality of 80 tests) and fatigue bending test (10 for each kind of needles, each tested at 3 different bending angles, resulting in a totality of 240 tests) have been conducted following the ISO 9626 norms. The final comparison among the obtained data have been conducted using a one way statistical analysis of variance (ANOVA). RESULTS: After stiffness tests the Carpule Free Flow injection needles and the traditional ones showed the same static behaviour, resulting in statistical comparable values of mean deflection at the maximum load allowed by ISO norms tests, whereas the 0.4 mm external diameter showed a statistically significant difference because the Carpule Free Flow needles achieved lower deflection values. After dynamic bending tests at 20 degrees both needle types showed the same behaviour, whereas at 30 degrees bending the Carpule Free Flow injection needles showed a higher number of breaks comparing to normal type, up to a maximum value of breaks (10 out of 10) for the 0.4 mm external diameter needles. After 50 degrees fatigue bending tests the Carpule Free Flow needles came to the break point after lower number of cycles than the Carpule needles. CONCLUSION: This study pointed out that, among anaesthesia injection needles, the Carpule Free Flow needles not only showed better clinical characteristics but also a mechanical behaviour, both static and dynamic, statistically similar to traditional ones, according to international standards. After fatigue bending higher than 20 degrees, exclusively made in this research in order to simulate critical or extreme conditions, all analysed Carpule Free Flow needles have been broken after a lower number of cycles. It is concluded that it is recommended not to repeatedly bend this kind of needles at more than 90 degrees. At the end of this study it may be suggested that this kind of needles cannot be repeatedly bended at angles more than 90 degrees.

A smart multifunctional drug delivery nanoplatform for targeting cancer cells.

Wirelessly guided magnetic nanomachines are promising vectors for targeted drug delivery, which have the potential to minimize the interaction between anticancer agents and healthy tissues. In this work, we propose a smart multifunctional drug delivery nanomachine for targeted drug delivery that incorporates a stimuli-responsive building block. The nanomachine consists of a magnetic nickel (Ni) nanotube that contains a pH-responsive chitosan hydrogel in its inner cavity. The chitosan inside the nanotube serves as a matrix that can selectively release drugs in acidic environments, such as the extracellular space of most tumors. Approximately a 2.5 times higher drug release from Ni nanotubes at pH = 6 is achieved compared to that at pH = 7.4. The outside of the Ni tube is coated with gold. A fluorescein isothiocyanate (FITC) labeled thiol-ssDNA, a biological marker, was conjugated on its surface by thiol-gold click chemistry, which enables traceability. The Ni nanotube allows the propulsion of the device by means of external magnetic fields. As the proposed nanoarchitecture integrates different functional building blocks, our drug delivery nanoplatform can be employed for carrying molecular drug conjugates and for performing targeted combinatorial therapies, which can provide an alternative and supplementary solution to current drug delivery technologies.

Electrochemically synthesized amorphous and crystalline nanowires: dissimilar nanomechanical behavior in comparison with homologous flat films.

The effects of constrained sample dimensions on the mechanical behavior of crystalline materials have been extensively investigated. However, there is no clear understanding of these effects in nano-sized amorphous samples. Herein, nanoindentation together with finite element simulations are used to compare the properties of crystalline and glassy CoNi(Re)P electrodeposited nanowires (ϕ ≈ 100 nm) with films (3 µm thick) of analogous composition and structure. The results reveal that amorphous nanowires exhibit a larger hardness, lower Young's modulus and higher plasticity index than glassy films. Conversely, the very large hardness and higher Young's modulus of crystalline nanowires are accompanied by a decrease in plasticity with respect to the homologous crystalline films. Remarkably, proper interpretation of the mechanical properties of the nanowires requires taking the curved geometry of the indented surface and sink-in effects into account. These findings are of high relevance for optimizing the performance of new, mechanically-robust, nanoscale materials for increasingly complex miniaturized devices.

Effects of Nd:YAG laser on dental enamel.

Caries prevention should be an important goal of the dentistry practitioner. In addition to traditional preventive techniques, laser beam has been a recent suggestion. This study aimed to evaluate Nd:YAG laser treatment effects on dental enamel surfaces, irradiated at different energy levels, by scanning electron microscopy (SEM) observations and surface micro-hardness tests to evaluate if caries prevention can be achieved by laser treatment. Forty human teeth were divided in four groups of 10 specimens each: in three groups the enamel surface was treated with three different laser beam energy levels, 60, 120 and 160 mJ, in one group the enamel was not lased. Five samples from each group were subjected to the Vickers microhardness test and five samples underwent SEM investigation. Results of the microhardness test demonstrated no significant differences between treated and non-treated dental enamel samples. SEM observation demonstrated a rougher enamel surface in all treated groups: the 60 mJ treated group showed tooth surfaces with vertical scratches, the 120 mJ treated group showed the enamel surface covered by craters and cracks, and the 160 mJ treated group showed a completely changed enamel structure with columns separated by voids and with a glass-like surface. These investigations demonstrated that dental enamel laser treatment at low energy levels (not >60 mJ) produces a protective glass-like surface, without the loss of its integrity and could be an advisable technique to prevent caries. Higher energy laser treatment leads to modifications of the enamel morphology such as craters and cracks, even if it does not cause any change in enamel hardness characteristics, which could be more useful in conservative dentistry.

A magnetic force sensor on a catheter tip for minimally invasive surgery.

This paper presents a magnetically guided catheter for minimally invasive surgery (MIS) with a magnetic force sensing tip. The force sensing element utilizes a magnetic Hall sensor and a miniature permanent magnet mounted on a flexible encapsulation acting as the sensing membrane. It is capable of high sensitivity and robust force measurements suitable for in-vivo applications. A second larger magnet placed on the catheter allows the catheter to be guided by applying magnetic fields. Precise orientation control can be achieved with an external magnetic manipulation system. The proposed device can be used in many applications of minimally invasive surgery (MIS) to detect forces applied on tissue during procedures or to characterize different types of tissue for diagnosis.

One-pot electrosynthesis of multi-layered magnetic metallopolymer nanocomposites.

Researchers have been investigating various methodologies for fabricating well-defined, homogenous composites consisting of nanoparticles (NPs) dispersed in a matrix. The main challenges are to prevent particle agglomerations during fabrication and to obtain nanoparticles whose size distribution could be tuned on demand. One of the methods that can provide these features is electrodeposition. We report for the first time the fabrication of a thin magnetic multilayer nanocomposite film by electrodeposition from one bath containing both a monomer and metal salts. Cobalt and cobalt-nickel NPs were deposited on conductive polymer polypyrrole thin films using different electrodeposition potentials and times. Multilayer nanocomposite films were fabricated by subsequent electrodeposition of polymer and nanoparticle layers. Scanning electron microscopy analysis showed that a wide range of NPs (70-230 nm) could be synthesized by manipulating growth potentials and times. The cobalt-nickel NPs were found to contain hexagonal close-packed (hcp) and face-centered cubic (fcc) phases based on X-ray diffraction and selected area electron diffraction. Magnetic measurements proved that both the single and the multi-layered nanocomposites were magnetic at room temperature.

Electroplated porous polypyrrole nanostructures patterned by colloidal lithography for drug-delivery applications.

Porous nanostructures of polypyrrole (Ppy) were fabricated using colloidal lithography and electrochemical techniques for potential applications in drug delivery. A sequential fabrication method was developed and optimized to maximize the coverage of the Ppy nanostructures and to obtain a homogeneous layer over the substrate. This was realized by masking with electrophoretically-assembled polystyrene (PS) nanospheres and then electroplating. Drug/biomolecule adsorption and the release characteristics for the porous nanostructures of Ppy were investigated using rhodamine B (Rh-B). Rh-B is an easily detectable small hydrophobic molecule that is used as a model for many drugs or biological substances. The porous Ppy nanostructures with an enhanced surface area exhibited higher Rh-B loading capacity than bulk planar films of Ppy. Moreover, tunability of surface morphology for further applications (e.g., sensing, cell adhesion) was demonstrated.