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In the past decade, the usage of soft materials, like gels, has allowed for a better control of the water release process into the substrate for cleaning interventions. Agar—a natural polysaccharide harvested from algae—has been used to perform cleaning of stone materials, gypsum works, and paintings with remarkably positive results. Agar presents the great advantage of being cheap, easily available, fast to produce and not toxic, allowing for more sustainable conservation works. More recently, a new type of agar fluid, agar foam, promises further control of the water release and ease of application on delicate surfaces. In the present study, this new type of agar, CO2 and N2O foams, has been characterized and compared with the conventional sol/gel agar system. Moreover, the cleaning effectiveness of the agar foam was tested both in laboratory conditions and in two case studies: a historical gypsum from the porch framing of the Abbey of Nonantola, and the 20th century gypsum cast of the Pietà Rondanini by Michelangelo, located in the Sforza Castle in Milan. The obtained results show that foaming changes the sol-gel transition temperature of the agar gel as well as incrementing its dissipative behavior. When freshly applied, the foams flow with a reduced velocity, thus allowing a better control and ease of application. Once gelified, they act as a soft solid-like material, as shown by their rheological properties. Moreover, it was found that CO2 foam slightly reduces the water release to the surface, while maintaining the moldability and ease of application. The study allows for the conclusion that agar foam offers an interesting alternative for delicate surfaces, with a non-coherent mineral deposit, and with complex geometries that often represent a challenge for the conventional agar applications [ABSTRACT FROM AUTHOR]

Retentive drug delivery systems (DDSs) are intended for prolonged residence and release inside hollow muscular organs, to achieve either local or systemic therapeutic goals. Recently, formulations based on shape memory polymers (SMPs) have gained attention in view of their special ability to recover a shape with greater spatial encumbrance at the target organ (e.g., urinary bladder or stomach), triggered by contact with biological fluids at body temperature. In this work, poly(vinyl alcohol) (PVA), a pharmaceutical-grade SMP previously shown to be an interesting 4D printing candidate, was employed to fabricate expandable organ-retentive prototypes by hot melt extrusion. With the aim of improving the mechanical resistance of the expandable DDS and slowing down relevant drug release, the application of insoluble permeable coatings based on either Eudragit® RS/RL or Eudragit® NE was evaluated using simple I-shaped specimens. The impact of the composition and thickness of the coating on the shape memory, swelling, and release behavior as well as on the mechanical properties of these specimens was thoroughly investigated and the effectiveness of the proposed strategy was demonstrated by the results obtained. [ABSTRACT FROM AUTHOR]

Cancer is one of the most life-threatening diseases worldwide. Despite the huge efforts, the failure rate of therapies remains high due to cells heterogeneity, so physiologically relevant models are strictly necessary. Bioprinting is a technology able to form highly complex 3D tissue models and enables the creation of large-scale constructs. In cancer research, Matrigel® is the most widely used matrix, but it is hardly bioprinted pure, without the use of any other bioink as reinforcement. Its complex rheological behavior makes the control with a standard bioprinting process nearly impossible. In this work, we present a customized bioprinting strategy to produce pure Matrigel® scaffolds with good shape fidelity. To this aim, we realized a custom-made volumetric dispensing system and performed printability evaluations. To determine optimal printing parameters, we analyzed fibers spreading ratio on simple serpentines. After identifying an optimal flow rate of 86.68 ± 5.77 µL/min and a printing speed of 10 mm/min, we moved forward to evaluate printing accuracy, structural integrity and other key parameters on single and multi-layer grids. Results demonstrated that Matrigel® was able to maintain its structure in both simple and complex designs, as well as in single and multilayer structures, even if it does not possess high mechanical strength. In conclusion, the use of volumetric dispensing allowed printing pure Matrigel® constructs with a certain degree of shape fidelity on both single and multiple layers. [ABSTRACT FROM AUTHOR]

The pulsatile-release Chronotopic™ system was conceived of as a drug-containing core surrounded by a coat made of swellable/soluble hydrophilic polymers, the latter being able to provide a programmable lag phase prior to drug liberation. This system was also proposed in a colon-targeting configuration, entailing a gastroresistant film to prevent early interaction of the inner coat with gastric fluids and enabling the attainment of a lag phase matching the small intestinal transit time. Over the years, various multiple-step manufacturing processes have been tested for the fabrication of the Chronotopic™ system in both its configurations. This work focused on the evaluation of 3D printing by fused deposition modeling in view of its potential towards product personalization, on demand one-step manufacturing and efficient scale down of batches. The feasibility of each part of the Chronotopic™ system was independently investigated starting from in-house made filaments, characterizing the resulting specimens for physico-technological and performance characteristics. The printing parameters identified as suitable during the set-up phase were then used to fabricate prototypes either in a single step for the pulsatile configuration or following two different fabrication approaches for the colon-targeting one. [ABSTRACT FROM AUTHOR]

Capsular devices for oral drug delivery were recently proposed and manufactured by injection molding (IM) as an evolution of traditional reservoir systems comprising a core and a functional coating. IM allowed the fabrication of capsule shells with release-controlling features based on the employed materials and the design characteristics. These features are independent of the drug, with significant savings in development time and costs. In previous work, IM was used to produce enteric-soluble capsules from blends of hydroxypropyl methylcellulose acetate succinate, with polyethylene glycol (PEG) as the plasticizer. In this work, the range of plasticizer concentrations and molar mass was broadened to evaluate in-depth how those parameters affect material processability and capsule performance over time. As expected, increasing the amount of the low molar mass plasticizer decreased the viscosity and modulus of the material. This simplified the molding process and enhanced the mechanical resistance of the shell, as observed during assembly. However, some samples turned out translucent, depending on several factors including storage conditions. This was attributed to plasticizer migration issues. Such results indicate that higher molar mass PEGs, while not significantly impacting on processability, lead to capsular devices with consistent performance in the investigated time lapse. [ABSTRACT FROM AUTHOR]