Hydroxypropyl cellulose methacrylate as a photo-patternable and biodegradable hybrid paper substrate for cell culture and other bioapplications

Cellulose-Based Composites as Scaffolds for Tissue Engineering: Recent Advances

Today, numerous studies have focused on the design of novel scaffolds for tissue engineering and regenerative medicine applications; however, several challenges still exist in terms of biocompatibility/cytocompatibility, degradability, cell attachment/proliferation, nutrient diffusion, large-scale production, and clinical translation studies. Greener and safer technologies can help to produce scaffolds with the benefits of cost-effectiveness, high biocompatibility, and biorenewability/sustainability, reducing their toxicity and possible side effects. However, some challenges persist regarding their degradability, purity, having enough porosity, and possible immunogenicity. In this context, naturally derived cellulose-based scaffolds with high biocompatibility, ease of production, availability, sustainability/renewability, and environmentally benign attributes can be applied for designing scaffolds. These cellulose-based scaffolds have shown unique mechanical properties, improved cell attachment/proliferation, multifunctionality, and enhanced biocompatibility/cytocompatibility, which make them promising candidates for tissue engineering applications. Herein, the salient developments pertaining to cellulose-based scaffolds for neural, bone, cardiovascular, and skin tissue engineering are deliberated, focusing on the challenges and opportunities.

Cytotoxicity evaluation of sodium lauryl sulfate in a paper-based 3D cell culture system

Because three-dimensional (3D) cell culture is more similar to in vivo cell microenvironments than two-dimensional (2D) cell culture, various 3D cell culture systems have been developed. Recently, paper has been used as a promising material for 3D cell culture and tissue models due to its flexibility, ease of manufacture, low cost, and widespread accessibility. In this study, we fabricated a paper-based 3D cell culture platform consisting of a hydrophilic region for cell attachment and a hydrophobic region printed with wax. Using this paper platform for 3D culture of L929 cells, we evaluated the cytotoxicity of a model substance, sodium lauryl sulfate (SLS), using water-soluble tetrazolium salt, Live/Dead, and luminescence assays. Then we compared those cytotoxicity results with results from a conventional 3D cell culture kit and 2D cell culture. We found that 3D cultured cells on paper responded more sensitively to SLS than 2D cultured cells, and the cytotoxicity of SLS to cells grown on the paper-based 3D cell culture platform was similar to that of cells grown using a commercially available 3D cell culture kit. Therefore, we expect that our paper-based 3D cell culture platform can be applied as a simple and facile tool for cell viability evaluation.

Development of electrospun mats based on hydrophobic hydroxypropyl cellulose derivatives

In this work, hydroxypropyl cellulose esters (HPCE) with long aliphatic chains were prepared and innovatively used in electrospinning to obtain hydroxypropyl cellulose (HPC)-based mats with enhanced resistance to moist environments. The described approach is very simple and does not require any post-treatment (e.g. cross-linking step) to overcome a major problem concerning the premature loss of properties of cellulose-based materials when in contact with moisture. HPCE-based electrospun mats were characterized in terms of their morphology, swelling ability and in vitro hydrolytic degradation. The mats exhibited a swelling capacity of over 115%, depending on the degree of substitution. The in vitro hydrolytic degradation tests showed the high structural integrity of the mats (< 5% weight loss) over a period of 30 days. The in vitro cytotoxicity tests showed that the mats of HPC esters are cytocompatible and promote the adhesion, proliferation and spreading of NIH3T3 fibroblast cells. These data suggest that the HPCE mats may be interesting materials for wound dressings, as well as for other tissue engineering applications.

Chemically Modified Biopolymers for the Formation of Biomedical Hydrogels

Biopolymers are natural polymers sourced from plants and animals, which include a variety of polysaccharides and polypeptides. The inclusion of biopolymers into biomedical hydrogels is of great interest because of their inherent biochemical and biophysical properties, such as cellular adhesion, degradation, and viscoelasticity. The objective of this Review is to provide a detailed overview of the design and development of biopolymer hydrogels for biomedical applications, with an emphasis on biopolymer chemical modifications and cross-linking methods. First, the fundamentals of biopolymers and chemical conjugation methods to introduce cross-linking groups are described. Cross-linking methods to form biopolymer networks are then discussed in detail, including (i) covalent cross-linking (e.g., free radical chain polymerization, click cross-linking, cross-linking due to oxidation of phenolic groups), (ii) dynamic covalent cross-linking (e.g., Schiff base formation, disulfide formation, reversible Diels-Alder reactions), and (iii) physical cross-linking (e.g., guest-host interactions, hydrogen bonding, metal-ligand coordination, grafted biopolymers). Finally, recent advances in the use of chemically modified biopolymer hydrogels for the biofabrication of tissue scaffolds, therapeutic delivery, tissue adhesives and sealants, as well as the formation of interpenetrating network biopolymer hydrogels, are highlighted.

Low impact leaching agents as remediation media for organotin and metal contaminated sediments

All over the world, elevated levels of metals and the toxic compound tributyltin (TBT) and its degradation products are found in sediments, especially close to areas associated with shipping and anthropogenic activities. Ports require regular removal of sediments. As a result, large volumes of often contaminated sediments must be managed. The aim of this study was to investigate enhanced leaching as a treatment method for organotin (TBT) and metal (Cu and Zn) contaminated marine sediments. Thus, enabling the possibility to reuse these cleaner masses e.g. in construction. In addition to using acid and alkaline leaching agents that extract the OTs and metals but reduce the management options post treatment, innovative alternatives such as EDDS, hydroxypropyl cellulose, humic acid, iron colloids, ultra-pure Milli-Q water, saponified tall oil ("soap"), and NaCl were tested. Organotin removal ranged from 36 to 75%, where the most efficient leaching agent was Milli-Q water, which was also the leaching agent achieving the highest removal rate for TBT (46%), followed by soap (34%). The TBT reduction accomplished by Milli-Q water and soap leaching enabled a change in Swedish sediment classification from the highest class to the second highest class. The highest reduction of Zn was in HPC leached samples (39% removal) and Cu in EDDS leached samples (33% removal). Although high metal and OT leaching were achieved, none of the investigated leaching agents are sufficiently effective for the removal of both metals and OTs. The results of this study indicate that leaching with ultra-clean water, such as Milli-Q water, may be sufficient to treat TBT contaminated sediments and potentially allow mass reuse.

Coacervate Thermoresponsive Polysaccharide Nanoparticles as Delivery System for Piroxicam

Low water solubility frequently compromises the therapeutic efficacy of drugs and other biologically active molecules. Here, we report on coacervate polysaccharide nanoparticles (CPNs) that can transport and release a model hydrophobic drug, piroxicam, to the cells in response to changes in temperature. The proposed, temperature-responsive drug delivery system is based on ionic derivatives of natural polysaccharides—curdlan and hydroxypropyl cellulose. Curdlan was modified with trimethylammonium groups, while the anionic derivative of hydroxypropyl cellulose was obtained by the introduction of styrenesulfonate groups. Thermally responsive nanoparticles of spherical shape and average hydrodynamic diameter in the range of 250–300 nm were spontaneously formed in water from the obtained ionic polysaccharides as a result of the coacervation process. Their morphology was visualized using SEM and AFM. The size and the surface charge of the obtained objects could be tailored by adjusting the polycation/polyanion ratio. Piroxicam (PIX) was effectively entrapped inside the nanoparticles. The release profile of the drug from the CPNs-PIX was found to be temperature-dependent in the range relevant for biomedical applications.

Engineered 3D Polymer and Hydrogel Microenvironments for Cell Culture Applications

The realization of biomimetic microenvironments for cell biology applications such as organ-on-chip, in vitro drug screening, and tissue engineering is one of the most fascinating research areas in the field of bioengineering. The continuous evolution of additive manufacturing techniques provides the tools to engineer these architectures at different scales. Moreover, it is now possible to tailor their biomechanical and topological properties while taking inspiration from the characteristics of the extracellular matrix, the three-dimensional scaffold in which cells proliferate, migrate, and differentiate. In such context, there is therefore a continuous quest for synthetic and nature-derived composite materials that must hold biocompatible, biodegradable, bioactive features and also be compatible with the envisioned fabrication strategy. The structure of the current review is intended to provide to both micro-engineers and cell biologists a comparative overview of the characteristics, advantages, and drawbacks of the major 3D printing techniques, the most promising biomaterials candidates, and the trade-offs that must be considered in order to replicate the properties of natural microenvironments.

Electrospin-Coating of Paper: A Natural Extracellular Matrix Inspired Design of Scaffold

Paper has recently found widespread applications in biomedical fields, especially as an alternative scaffolding material for cell cultures, owing to properties such as its fibrous nature, porosity and flexibility. However, paper on its own is not an optimal material for cell cultures as it lacks adhesion moieties specific to mammalian cells, and modifications such as hydrogel integration and chemical vapor deposition are necessary to make it a favorable scaffolding material. The present study focuses on modification of filter paper through electrospin-coating and dip-coating with polycaprolactone (PCL), a promising biomaterial in tissue engineering. Morphological analysis, evaluation of cell viability, alkaline phosphatase (ALP) activity and live/dead assays were conducted to study the potential of the modified paper-based scaffold. The results were compared to filter paper (FP) and electrospun PCL (ES-PCL) as reference samples. The results indicate that electrospin-coating paper is a simple and efficient way of modifying FP. It not only improves the morphology of the deposited electrospun layer through reduction of the fiber diameter by nearly 75%, but also greatly reduces the scaffold fabrication time compared to ES-PCL. The biochemical assays (Resazurin and ALP) indicate that electrospin-coated filter paper (ES-PCL/FP) provides significantly higher readings compared to all other groups. The live/dead results also show improved cell-distribution and cell-scaffold attachment all over the ES-PCL/FP.

Hydroxypropyl cellulose as a green polymer for thermo-responsive aqueous foams

Hydroxypropyl cellulose (HPC) is a surface active polymer that can change its solubility as a function of temperature. This makes HPC interesting for responsive foams, where macroscopic properties need to be reversibly changed on demand. Analysis of aqueous HPC foams as a function of temperature showed a moderate decrease in foam half-life time from 9000 to 4000 s, when the temperature was increased. However, within a narrow temperature range of ±2 °C a dramatic decrease in half-life time to <120 s was observed at 43 °C in the absence and at 31 °C in the presence of 0.7 M NaCl. These drastic changes are highly reversible and are associated to the lower critical solution temperatures (LCST) of HPC in aqueous solutions. In fact, dynamic light scattering experiments indicate that HPC molecules form aggregates at temperatures >31 °C (0.7 M NaCl) and >43 °C (0 M NaCl), which shrink in size when the temperature is increased further. From these results, we conclude that the LCST of 1 MDa HPC is at 43 °C when no salt is present and is at 31 °C in aqueous solutions with 0.7 M NaCl. In addition, shear rheology of bulk solutions and surface tensiometry indicate that the solution's viscosity and the surface pressure dramatically change at the respective LCSTs. Obviously, the solvent's viscosity triggers substantial changes in foam drainage at the LCST, which is shown to be the main driving force for the temperature responsiveness of HPC foams.

Recent Advances in Modified Cellulose for Tissue Culture Applications

Tissue engineering is a rapidly advancing field in regenerative medicine, with much research directed towards the production of new biomaterial scaffolds with tailored properties to generate functional tissue for specific applications. Recently, principles of sustainability, eco-efficiency and green chemistry have begun to guide the development of a new generation of materials, such as cellulose, as an alternative to conventional polymers based on conversion of fossil carbon (e.g., oil) and finding technologies to reduce the use of animal and human derived biomolecules (e.g., foetal bovine serum). Much of this focus on cellulose is due to it possessing the necessary properties for tissue engineering scaffolds, including biocompatibility, and the relative ease with which its characteristics can be tuned through chemical modification to adjust mechanical properties and to introduce various surface modifications. In addition, the sustainability of producing and manufacturing materials from cellulose, as well as its modest cost, makes cellulose an economically viable feedstock. This review focusses specifically on the use of modified cellulose materials for tissue culturing applications. We will investigate recent techniques used to promote scaffold function through physical, biochemical and chemical scaffold modifications, and describe how these have been utilised to reduce reliance on the addition of matrix ligands such as foetal bovine serum.

An electrochemiluminescence lab-on-paper device for sensitive detection of two antigens at the MCF-7 cell surface based on porous bimetallic AuPd nanoparticles

Sensitive detection of two antigens at the MCF-7 cell surface based on porous bimetallic AuPd nanopar.

Low-cost bioanalysis on paper-based and its hybrid microfluidic platforms

Low-cost assays have broad applications ranging from human health diagnostics and food safety inspection to environmental analysis. Hence, low-cost assays are especially attractive for rural areas and developing countries, where financial resources are limited. Recently, paper-based microfluidic devices have emerged as a low-cost platform which greatly accelerates the point of care (POC) analysis in low-resource settings. This paper reviews recent advances of low-cost bioanalysis on paper-based microfluidic platforms, including fully paper-based and paper hybrid microfluidic platforms. In this review paper, we first summarized the fabrication techniques of fully paper-based microfluidic platforms, followed with their applications in human health diagnostics and food safety analysis. Then we highlighted paper hybrid microfluidic platforms and their applications, because hybrid platforms could draw benefits from multiple device substrates. Finally, we discussed the current limitations and perspective trends of paper-based microfluidic platforms for low-cost assays.

Paper-based electrochemiluminescence origami cyto-device for multiple cancer cells detection using porous AuPd alloy as catalytically promoted nanolabels

The detection of cancer cells is important and fundamental for cancer diagnosis and therapy, which has attracted considerable interest recently. Although traditional cyto-sensors have been widely explored due to their high sensitivity and selectivity, it is still a challenge to develop a low-cost, portable, disposable, fast, and easy-to-use cancer cell detection method for applying in the field of cancer diagnosis and therapy. Herein, to address these challenges, we developed a microfluidic paper-based electrochemiluminescence origami cyto-device (μ-PECLOC), in which aptamers modified 3D macroporous Au-paper electrodes were employed as the working electrodes and efficient platforms for the specific cancer cells capture. Owing to the effective disproportionation of hydrogen peroxide and specific recognition of mannose on cell surface, concanavalin-A conjugated porous AuPd alloy nanoparticles were introduced into this μ-PECLOC as the catalytically promoted nanolabels for peroxydisulfate ECL system. Under the optimal conditions, the proposed μ-PECLOC exhibited excellent analytical performance with good stability, reproducibility, and accuracy, towards the cyto-sensing of four types of cancer cells indicating the potential applications to facilitate effective and multiple early cancer diagnosis and clinical treatment.