3D bioprinting of gastrointestinal cancer models: A comprehensive review on processing, properties, and therapeutic implications.

Gastrointestinal tract (GIT) malignancies are an important public health problem considering the increased incidence in recent years and the high morbidity and mortality associated with it. GIT malignancies constitute 26% of the global cancer incidence burden and 35% of all cancer-related deaths. Gastrointestinal cancers are complex and heterogenous diseases caused by the interplay of genetic and environmental factors. The tumor microenvironment (TME) of gastrointestinal tract carcinomas is dynamic and complex; it cannot be recapitulated in the basic two-dimensional cell culture systems. In contrast, three-dimensional (3D) in vitro models can mimic the TME more closely, enabling an improved understanding of the microenvironmental cues involved in the various stages of cancer initiation, progression, and metastasis. However, the heterogeneity of the TME is incompletely reproduced in these 3D culture models, as they fail to regulate the orientation and interaction of various cell types in a complex architecture. To emulate the TME, 3D bioprinting has emerged as a useful technique to engineer cancer tissue models. Bioprinted cancer tissue models can potentially recapitulate cancer pathology and increase drug resistance in an organ-mimicking 3D environment. In this review, we describe the 3D bioprinting methods, bioinks, characterization of 3D bioprinted constructs, and their application in developing gastrointestinal tumor models that integrate their microenvironment with different cell types and substrates, as well as bioprinting modalities and their application in therapy and drug screening. We review prominent studies on the 3D bioprinted esophageal, hepatobiliary, and colorectal cancer models. In addition, this review provides a comprehensive understanding of the cancer microenvironment in printed tumor models, highlights current challenges with respect to their clinical translation, and summarizes future perspectives.

Poly (caprolactone)/sodium-alginate-functionalized halloysite clay nanotube nanocomposites: Potent biocompatible materials for wound healing applications.

In this study, halloysite nanotubes (HNTs) were subjected to surface functionalization using sodium alginate and incorporated into poly(caprolactone) (PCL) to fabricate nanocomposites for potential wound healing applications. The nanocomposite films were fabricated through the solution casting technique and characterized using various instrumental methods. The films exhibited enhanced thermal and mechanical properties. FE-SEM and AFM analyses confirmed the uniform dispersion of the HNTs and increased roughness of the films, respectively. The swelling properties, in-vitro enzymatic degradation, and anti-inflammatory activity of the films were also analyzed. The MTT assay performed using NIH3T3 cell lines revealed enhanced cell proliferation (126 ± 1.38) of 5 wt% film. Besides, the cell adhesion tests of the films revealed their cytocompatibility. The scratch assay tests conducted for observing the effectiveness of the films for wound closure showed that the 5 wt% film offered a higher rate of fibroblast cell migration (32.24 ± 0.49) than the pristine PCL film. The HRBCMS assay demonstrated the hemocompatibility of these films. The biological test results indicated the delayed enzymatic degradability and haemocompatiblity of nanocomposites with enhanced cell adhesion, cell proliferation, and cell migration capabilities with respect to fibroblast cells. In summary, the synthesized nanocomposite films can be effectively used in wound healing applications after further clinical trials.

Effects of reinforcement of sodium alginate functionalized halloysite clay nanotubes on thermo-mechanical properties and biocompatibility of poly (vinyl alcohol) nanocomposites.

In the present work sodium alginate functionalized halloysite nanotubes (HNTs) reinforced poly (vinyl alcohol) nanocomposite films were prepared by solution casting technique. Sodium alginate surface functionalizing on the HNTs through hydrogen bonding was confirmed by spectroscopic and morphological analysis. The functionalized HNTs were successfully incorporated into the PVA matrix. Further, the films were characterized by using FTIR, TGA, XRD, SEM, AFM, UTM, WCA and swelling ratio analysis. The obtained results indicated improved physico-thermal properties, and uniform distribution of nanotubes in the matrix and roughness of the surface compared with the pristine PVA films. After inclusion of functionalized nanotubes causes enhancement of tensile strength as well as young's modulus of the nanocomposite films. Water contact angle measurement was carried out to know the hydrophilic or hydrophobic nature of the films and results were correlated with swelling ratio analysis. Furthermore, the films were analyzed for in-vitro biocompatibility studies. In -vitro enzymatic degradation was carried out in PBS media and cellular behaviour studies were analyzed using NIH3T3 cell lines. The results showed enhancement in the enzymatic degradation, proliferation, adhesion activity compared to that of pristine PVA films. In extension, nanocomposite films were subjected to hemocompatibility studies using human erythrocyte. The results revealed that nanocomposite films were biocompatible and hemocompatible. The fabricated films can be used in biomedical application.

Functionalization of halloysite nanotube with chitosan reinforced poly (vinyl alcohol) nanocomposites for potential biomedical applications.

The present study reports the preparation of novel surface functionalized halloysite nanotubes (HNTs) with chitosan incorporated Poly (vinyl alcohol) (PVA) nanocomposite films with desirable properties. Surface functionalization of HNTs with Chitosan through hydrogen bonding via acylation with succinic anhydride; supramolecular interaction was confirmed by spectroscopic and morphological analysis. The functionalized HNTs incorporated in the PVA matrix were subjected to FTIR studies, Atomic Force Microscopy, Scanning Electron Microscopy, X-ray diffraction, thermal, mechanical properties, Water Contact Angle, swelling ratio analysis and in-vitro biocompatibility studies. Results of the morphological studies showed that functionalized HNTs were uniformly dispersed and showed improved surface roughness with increasing weight percent of functionalized HNTs in the films. The studies revealed significant enhancement in the mechanical and thermal properties compared with the pristine PVA film. The hydrophilic or hydrophobic nature of films were analysed with WCA and results were compared with swelling studies. Furthermore, in vitro enzymatic degradation and cellular behaviour studies performed on mouse fibroblast (NIH3T3) cells and results confirmed enhanced proliferative and adhesion activity of nanocomposite films compared to that of pristine PVA films. In addition, hemocompatibility studies carried out using human erythrocytes revealed the biocompatible and hemocompatible of nanocomposite films indicating their greater potential for tissue engineering.

Three-Dimensional Printing of a LiFePO4/Graphite Battery Cell via Fused Deposition Modeling.

Among the 3D-printing technologies, fused deposition modeling (FDM) represents a promising route to enable direct incorporation of the battery within the final 3D object. Here, the preparation and characterization of lithium iron phosphate/polylactic acid (LFP/PLA) and SiO2/PLA 3D-printable filaments, specifically conceived respectively as positive electrode and separator in a lithium-ion battery is reported. By means of plasticizer addition, the active material loading within the positive electrode is raised as high as possible (up to 52 wt.%) while still providing enough flexibility to the filament to be printed. A thorough analysis is performed to determine the thermal, electrical and electrochemical effect of carbon black as conductive additive in the positive electrode and the electrolyte uptake impact of ceramic additives in the separator. Considering both optimized filaments composition and using our previously reported graphite/PLA filament for the negative electrode, assembled and "printed in one-shot" complete LFP/Graphite battery cells are 3D-printed and characterized. Taking advantage of the new design capabilities conferred by 3D-printing, separator patterns and infill density are discussed with a view to enhance the liquid electrolyte impregnation and avoid short-circuits.

Study on the morphological and biocompatible properties of chitosan grafted silk fibre reinforced PVA films for tissue engineering applications.

The current study delineates the preparation of novel chitosan grafted silk fibre reinforced Poly (vinyl alcohol) (PVA) composite films with desirable properties. Although silk fibroin has been extensively used for various biomedical applications, its properties could be further re-tailored for its suitability in the field of regenerative medicine. Chitosan was successfully grafted over silk, via acylation with succinic anhydride and thereby the fibres were incised and used for the preparation of the films. The grafted silk fibre reinforced PVA films were subjected to FTIR studies, microscopic analysis by atomic force microscopy (AFM) and optical microscopy techniques, X-ray diffraction (XRD) analysis and further evaluated for in vitro biocompatibility studies. The composite films demonstrated improved surface roughness with increasing concentration of the fibre and its dispersion in the polymer matrix was observed. Furthermore, in vitro biocompatibility and cellular behaviour such as adhesion and proliferation of mouse fibroblasts as well as astrocyte cells was studied and the results showed improved proliferative activity, when compared to the pristine PVA films. These results were further supported by the results confirmed by MTT assay demonstrating the films to be non-toxic. The efficiency and feasibility of the films to be used for tissue engineering, was further evaluated by haemocompatibility studies using human erythrocytes, thus making them a potential material to be used for biomedical applications.

Plasticized-starch/poly(ethylene oxide) blends prepared by extrusion.

Blends based on plasticized-wheat starch (as matrix or rich phase) and poly(ethylene oxide) (PEO) (as dispersed phase) were prepared by melt processing in a twin-screw extruder. The extrusion of the plasticized-starch is significantly facilitated by blending with PEO. Plasticized-starch and PEO are immiscible in the range of the investigated blend ratios (90/10-50/50). The phase inversion takes place when the PEO content is 50 wt.% in the blend. Both the thermal stability and the tensile properties of plasticized-starch are improved by blending with PEO. Also, a synergistic effect between plasticized-starch and PEO is noticed at 25-40 wt.% PEO content in the blend, the Young's modulus of the materials obtained being the highest and higher than both neat polymer components at those blending ratios.