The integration of multifunctional elements directly embedded in three-dimensional (3D) printed parts is the cutting-edge of additive manufacturing (AM) and it is crucial for enlarging as well as for ...strengthening AM role in industrial applications. Here, a straightforward and low-cost method that synergically combines stereolithography (SLA) and selective electroless metallization (EM) is presented for the fabrication of 3D parts characterized by complex shapes and end-use multifunctionalities (conductive, magnetic, mechanical properties). To this end, a novel photocurable composite based on acrylate resin loaded with nickel (Ni) particles is developed for high-resolution SLA-printing of features with self-catalytic properties for EM. Ni particles are loaded in the resin to trigger metal deposition avoiding time consuming and expensive laser-based surface activation. The effect of Ni content on SLA behavior as well as on the efficiency of EM process is studied. Metallized SLA cured samples show good electrical and magnetic properties as well as improved robustness with respect to their non-loaded counterparts. Then, selective metallization of 3D printed parts is successfully achieved by implementing a multi-material SLA-printing where loaded and non-loaded resins are properly interchanged with strong adhesion at the interface, thus offering a cost-effective approach for rapid prototyping of functional free-form features on 3D structures.
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Abstract
Electrospinning is a powerful and versatile technique to produce efficient, specifically tailored and high-added value anodes for lithium ion batteries. Indeed, electrospun carbon nanofibers ...(CNFs) provide faster intercalation kinetics, shorter diffusion paths for ions/electrons transport and a larger number of lithium insertion sites with respect to commonly employed powder materials. With a view to further enhance battery performances, red phosphorous (RP) is considered one of the most promising materials that can be used in association with CNFs. RP/CNFs smart combinations can be exploited to overcome RP low conductivity and large volume expansion during cycling. In this context, we suggest a simple and cost effective double-step procedure to obtain high-capacity CNFs anodes and to enhance their electrochemical performances with the insertion of red phosphorous in the matrix. We propose a simple dropcasting method to confine micro- and nanosized RP particles within electrospun CNFs, thus obtaining a highly efficient, self-standing, binder-free anode. Phosphorous decorated carbon mats are characterized morphologically and tested in lithium ion batteries. Results obtained demonstrate that the reversible specific capacity and the rate capability of the obtained composite anodes is significantly improved with respect to the electrospun carbon mat alone.
Targeted drug delivery is currently emerging as a promising approach to overcome the limits of currently employed administration techniques. The most convenient methodology to control drug delivery ...is the application of stimuli-responsive materials, which can release drugs only when required, to remotely controlled microdevices able to navigate human body. Thanks to this synergy, release can be controlled both spatially and temporally. Spatial control is guaranteed by the maneuverability of the devices, which can be precisely guided to release in targeted locations. Temporal control, conversely, is guaranteed by the functionalization introduced in the stimuli-responsive material. In this context, the present work describes the coating of magnetically controlled microdevices with functionalized alginate-based hydrogels able to release drugs at pH values lower than 4.5. Hydrogels are functionalized binding the drug with either an azidoethyl ester bond or an amidic bond, following an innovative synthesis route. After fabrication, release from hydrogel coated microdevices as a function of the environmental pH is characterized. Finally, devices are magnetically actuated and the possibility to achieve spatially and temporally controlled release is demonstrated. The functional microtransporters described in the present work are particularly promising for in-vivo applications in environments where pH differences are present, like the digestive apparatus.
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•Functionalized alginate hydrogels for pH controlled drug release are synthesized.•Functionalization is designed to allow sustained drug release only at pH lower than 4.5.•Hydrogels are applied on magnetically steerable devices able to navigate human body.•Hydrogel coating onto microrobots create drug carriers that can reach specific target sites.•Hydrogel coating functionalization can guarantee the release of drugs only in the target site.
In the present work the electrodeposition of zinc-nickel alloys with 15-20 wt.% nickel from non-aqueous solutions based on ethylene glycol is investigated. Potentiostatic deposition conditions are ...used, which are found to offer optimal coating quality and superior control over composition. In addition, ammonium chloride is evaluated as additive to partially suppress zinc incorporation into the deposit and to enhance layer quality. Layers composition, surface morphology of the deposits and their anticorrosive properties are investigated. The electrochemical characteristics of the Zn-Ni electrolytes are studied using cyclic voltammetry measurements. From the phase composition point view, X-ray diffraction results confirm that a metastable γ phase is present in the as deposited Zn-Ni alloys with nickel content 16-18 wt.%. Corrosion tests show that the barrier behaviour against corrosion of Zn-Ni films electrodeposited from the NH4Cl containing bath is superior in comparison to layers plated from an additive-free bath. The use of the additive enlarges the grains and provides a compact surface structure, which upskills the anticorrosive behaviour of the deposit.
The family of technologies collectively known as additive manufacturing (AM) technologies, and often called 3D-printing technologies, is rapidly revolutionizing industrial production. AM’s potential ...to produce intricate and customized parts starting from a digital 3D model makes it one of the main pillars for the forthcoming Industry 4.0. Thanks to its advantages over traditional manufacturing methodologies, AM finds potential applicability in virtually all production fields. As a natural consequence of this, research in this field is primarily focused on the development of novel materials and techniques for 3D printing. This Special Issue of Technologies, titled “3D Printing Technologies”, aims at promoting the latest knowledge in materials, processes, and applications for AM. It is composed of six contributions, authored by influential scientists in the field of advanced 3D printing. The intended audience includes professors, graduate students, researchers, engineers and specialists working in the field of AM.
Microrobotic prototypes for water cleaning are produced combining stereolithography 3D printing and wet metallization. Different metallic layers are deposited on 3D printed parts using both ...electroless and electrolytic deposition to impart required functionalities. In particular, by exploiting the flexibility and versatility of electrolytic codeposition, pollutants photodegradation and bacteria killing are for the first time combined on the same device by coating it with a composite nanocoating containing titania nanoparticles in a silver matrix. The microstructure of the microrobots thus obtained is fully characterized and they are successfully actuated by applying rotating magnetic fields. From the water cleaning point of view, devices show evident photocatalytic activity towards water pollutants and antimicrobial activity for gram negative bacteria.
In the last few years, the manufacturing of microelectromechanical systems (MEMS) by means of innovative tridimensional and bidimensional printing technologies has significantly catalyzed the ...attention of researchers. Inkjet material deposition, in particular, can become a key enabling technology for the production of polymer-based inertial sensors characterized by low cost, high manufacturing scalability and superior sensitivity. In this paper, a fully inkjet-printed polymeric accelerometer is proposed, and its manufacturing steps are described. The manufacturing challenges connected with the inkjet deposition of SU-8 as a structural material are identified and addressed, resulting in the production of a functional spring-mass sensor. A step-crosslinking process allows optimization of the final shape of the device and limits defects typical of inkjet printing. The resulting device is characterized from a morphological point of view, and its functionality is assessed in performing optical readout. The acceleration range of the optimized device is 0–0.7 g, its resolution is 2 × 10−3 g and its sensitivity is 6745 nm/g. In general, the work demonstrates the feasibility of polymeric accelerometer production via inkjet printing, and these characteristic parameters demonstrate their potential applicability in a broad range of uses requiring highly accurate acceleration measurements over small displacements.
Inflammation and oxidative stress characterize sepsis and determine its severity. In this study, we investigated the relationship between albumin oxidation and sepsis severity in a selected cohort of ...patients from the Albumin Italian Outcome Study (ALBIOS). A retrospective analysis was conducted on the oxidation forms of human albumin human mercapto-albumin (HMA), human non-mercapto-albumin form 1 (HNA1) and human non-mercapto-albumin form 2 (HNA2) in 60 patients with severe sepsis or septic shock and 21 healthy controls. The sepsis patients were randomized (1:1) to treatment with 20% albumin and crystalloid solution or crystalloid solution alone. The albumin oxidation forms were measured at day 1 and day 7. To assess the albumin oxidation forms as a function of oxidative stress, the 60 sepsis patients, regardless of the treatment, were grouped based on baseline sequential organ failure assessment (SOFA) score as surrogate marker of oxidative stress. At day 1, septic patients had significantly lower levels of HMA and higher levels of HNA1 and HNA2 than healthy controls. HMA and HNA1 concentrations were similar in patients treated with albumin or crystalloids at day 1, while HNA2 concentration was significantly greater in albumin-treated patients (
p
< 0.001). On day 7, HMA was significantly higher in albumin-treated patients, while HNA2 significantly increased only in the crystalloids-treated group, reaching values comparable with the albumin group. When pooling the septic patients regardless of treatment, albumin oxidation was similar across all SOFA groups at day 1, but at day 7 HMA was lower at higher SOFA scores. Mortality rate was independently associated with albumin oxidation levels measured at day 7 (HMA log-rank = 0.027 and HNA2 log-rank = 0.002), irrespective of treatment group. In adjusted regression analyses for 90-day mortality, this effect remained significant for HMA and HNA2. Our data suggest that the oxidation status of albumin is modified according to the time of exposure to oxidative stress (differences between day 1 and day 7). After 7 days of treatment, lower SOFA scores correlate with higher albumin antioxidant capacity. The trend toward a positive effect of albumin treatment, while not statistically significant, warrants further investigation.
In the last few decades, the introduction of microrobotics has drastically changed the way medicine will be approached in the future. The development of untethered steerable microdevices able to ...operate in vivo inside the human body allows a high localization of the therapeutical action, thus limiting invasiveness and possible medical complications. This approach results are particularly useful in drug delivery, where it is highly beneficial to administer the drug of choice exclusively to the target organ to avoid overdosage and side effects. In this context, drug releasing layers can be loaded on magnetically moveable platforms that can be guided toward the target organ to perform highly targeted release. In the present paper, we evaluate the possible application of alginate hydrogel layers on moveable platforms manufactured by coupling additive manufacturing with wet metallization. Such alginate layers are reticulated using three different physical crosslinkers: Ca, Zn or Mn. Their effect on drug release kinetics and on device functionality is evaluated. In the case of alginate reticulated using Mn, the strongly pH dependent behavior of the resulting hydrogel is evaluated as a possible way to introduce a triggered release functionality on the devices.
Targeted drug delivery from untethered microrobots is a topic of major interest in current biomedical research. The possibility to load smart materials able to administer active principles on ...remotely
guidable microdevices constitutes one of the most attractive opportunities to overcome the drawbacks of classical untargeted delivery methodologies. Hydrogels, in particular, are ideal candidates as drug-carrying materials due to their biocompatibility, low cost, and ease of manufacturing. On the other hand, these polymers suffer from poor control over release rate and overall released amount. Starting from these premises, the present article demonstrates the possibility to tune the release of hydrogels applied on magnetically steerable microrobots by fabricating microsystems
layer-by-layer self-assembly. By doing this, the diffusion of chemicals from the hydrogel layers to the external environment can be optimized and the phenomenon of burst release can be strongly limited. The microrobotic platforms employed to transport the hydrogel active material are fabricated by employing 3D printing in combination with wet metallization and present a gold layer on their surface to enhance biocompatibility. The maneuverability of microdevices coated with both thin and thick multilayers is investigated, individuating optimized parameters for efficient actuation.
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