Application of Metal Nanoparticle⁻Hydrogel Composites in Tissue Regeneration

Development of Polymer-Assisted Nanoparticles and Nanogels for Cancer Therapy: An Update

With cancer remaining as one of the main causes of deaths worldwide, many studies are undergoing the effort to look for a novel and potent anticancer drug. Nanoparticles (NPs) are one of the rising fields in research for anticancer drug development. One of the key advantages of using NPs for cancer therapy is its high flexibility for modification, hence additional properties can be added to the NPs in order to improve its anticancer action. Polymer has attracted considerable attention to be used as a material to enhance the bioactivity of the NPs. Nanogels, which are NPs cross-linked with hydrophilic polymer network have also exhibited benefits in anticancer application. The characteristics of these nanomaterials include non-toxic, environment-friendly, and variable physiochemical properties. Some other unique properties of polymers are also attributed by diverse methods of polymer synthesis. This then contributes to the unique properties of the nanodrugs. This review article provides an in-depth update on the development of polymer-assisted NPs and nanogels for cancer therapy. Topics such as the synthesis, usage, and properties of the nanomaterials are discussed along with their mechanisms and functions in anticancer application. The advantages and limitations are also discussed in this article.

Nanocomposite Membrane Scaffolds for Cell Function Maintaining for Biomedical Purposes

Nanocomposite multilayered membrane coatings have been widely used experimentally to enhance biomedical materials surfaces. By the selection of reliable components, such systems are functionalized to be adjusted to specific purposes. As metal nanoparticles can reduce bacterial cell adhesion, the idea of using gold and silver nanoparticles of unique antimicrobial properties within membrane structure is outstandingly interesting considering dressings facilitating wound healing. The study was aimed to explore the interface between eukaryotic cells and wound dressing materials containing various nanoelements. The proposed systems are based on polyethyleneimine and hydroxyapatite thin layers incorporating metallic nanoparticles (silver or gold). To examine the structure of designed materials scanning electron and transmission electron microscopies were applied. Moreover, Fourier-transform infrared and energy-dispersive X-ray spectroscopies were used. Additionally, water contact angles of the designed membranes and their transport properties were estimated. The functioning of human fibroblasts was examined via flow cytometry to assess the biocompatibility of developed shells in the aspect of their cytotoxicity. The results indicated that designed nanocomposite membrane scaffolds support eukaryotic cells' functioning, confirming that the elaborated systems might be recommended as wound healing materials.

Applications of nanotechnology in 3D printed tissue engineering scaffolds

Tissue engineering is an interdisciplinary field that aims to combine life sciences and engineering to create therapies that regenerate functional tissue. Early work in tissue engineering mostly used materials as inert scaffolding structures, but research has shown that constructing scaffolds from biologically active materials can help with regeneration by enabling cell-scaffold interactions or release of factors that aid in regeneration. Three-dimensional (3D) printing is a promising technique for the fabrication of structurally intricate and compositionally complex tissue engineering scaffolds. Such scaffolds can be functionalized with techniques developed by nanotechnology research to further enhance their ability to stimulate regeneration and interact with cells. Nanotechnological components, nanoscale textures, and microscale/nanoscale printing can all be incorporated into the manufacture of 3D printed scaffolds. This review discusses recent advancements in the merging of nanotechnology with 3D printed tissue engineering scaffolds, with a focus on applications of nanoscale components, nanoscale texture, and innovative printing techniques and the effects observed in vitro and in vivo.

3D Bioprinted Bacteriostatic Hyperelastic Bone Scaffold for Damage-Specific Bone Regeneration

Current strategies for regeneration of large bone fractures yield limited clinical success mainly due to poor integration and healing. Multidisciplinary approaches in design and development of functional tissue engineered scaffolds are required to overcome these translational challenges. Here, a new generation of hyperelastic bone (HB) implants, loaded with superparamagnetic iron oxide nanoparticles (SPIONs), are 3D bioprinted and their regenerative effect on large non-healing bone fractures is studied. Scaffolds are bioprinted with the geometry that closely correspond to that of the bone defect, using an osteoconductive, highly elastic, surgically friendly bioink mainly composed of hydroxyapatite. Incorporation of SPIONs into HB bioink results in enhanced bacteriostatic properties of bone grafts while exhibiting no cytotoxicity. In vitro culture of mouse embryonic cells and human osteoblast-like cells remain viable and functional up to 14 days on printed HB scaffolds. Implantation of damage-specific bioprinted constructs into a rat model of femoral bone defect demonstrates significant regenerative effect over the 2-week time course. While no infection, immune rejection, or fibrotic encapsulation is observed, HB grafts show rapid integration with host tissue, ossification, and growth of new bone. These results suggest a great translational potential for 3D bioprinted HB scaffolds, laden with functional nanoparticles, for hard tissue engineering applications.

One-step green synthesis of 2D Ag-dendrite-embedded biopolymer hydrogel beads as a catalytic reactor

Silver (Ag) nanocrystals with a dendritic structure have attracted intensive attention because of their unique structural properties, which include abundant sharp corners and edges that provide a large number of active atoms. However, the synthesis of Ag dendrites via a simple and environmentally friendly method under ambient conditions remains a challenge. In this paper, we report a simple water-based green method for the production of biopolymer hydrogel beads embedded with Ag dendrites without using an additional reducing agent, stabilizer, or crosslinking agent. The obtained Ag dendrites exhibit a unique two-dimensional (2D) structure rather than a conventional three-dimensional structure because Ag⁺ ions are reduced on the surface of the solid-phase hydrogel beads and grow into crystals. Reasonable mechanisms explaining the formation of the nanocomposite hydrogel beads and the formation of 2D Ag dendrites in the hydrogel are proposed on the basis of our observations and results. The hydrogel beads embedded the 2D Ag dendrites were used as an environmentally friendly catalytic reactor, and their catalytic performance was evaluated by adopting the reduction of 4-nitrophenol to 4-aminophenol with NaBH₄ as a model reaction.

Alginate hydrogel beads embedded with 2D Ag dendrites were synthesized by simply adding aqueous alginate droplets to an aqueous AgNO₃ solution.

Gold Nanoparticle-Based Platforms for Diagnosis and Treatment of Myocardial Infarction

In recent years, an increasing rate of mortality due to myocardial infarction (MI) has led to the development of nanobased platforms, especially gold nanoparticles (AuNPs), as promising nanomaterials for diagnosis and treatment of MI. These promising NPs have been used to develop different nanobiosensors, mainly optical sensors for early detection of biomarkers as well as biomimetic/bioinspired platforms for cardiac tissue engineering (CTE). Therefore, in this Review, we presented an overview on the potential application of AuNPs as optical (surface plasmon resonance, colorimetric, fluorescence, and chemiluminescence) nanobiosensors for early diagnosis and prognosis of MI. On the other hand, we discussed the potential application of AuNPs either alone or with other NPs/polymers as promising three-dimensional (3D) scaffolds to regulate the microenvironment and mimic the morphological and electrical features of cardiac cells for potential application in CTE. Furthermore, we presented the challenges and ongoing efforts associated with the application of AuNPs in the diagnosis and treatment of MI. In conclusion, this Review may provide outstanding information regarding the development of AuNP-based technology as a promising platform for current MI treatment approaches.

Spatiotemporally Controlled Photoresponsive Hydrogels: Design and Predictive Modeling from Processing through Application

Photoresponsive hydrogels (PRHs) are soft materials whose mechanical and chemical properties can be tuned spatially and temporally with relative ease. Both photo-crosslinkable and photodegradable hydrogels find utility in a range of biomedical applications that require tissue-like properties or programmable responses. Progress in engineering with PRHs is facilitated by the development of theoretical tools that enable optimization of their photochemistry, polymer matrices, nanofillers, and architecture. This review brings together models and design principles that enable key applications of PRHs in tissue engineering, drug delivery, and soft robotics, and highlights ongoing challenges in both modeling and application.

New volumetric CNT-doped gelatin-cellulose scaffolds for skeletal muscle tissue engineering

Currently, the fabrication of scaffolds for engineered skeletal muscle tissues is unable to reach the millimeter size. The main drawbacks are the poor nutrient diffusion, lack of an internal structure to align the precursor cells, and poor mechanical and electric properties. Herein, we present a combination of gelatin-carboxymethyl cellulose materials polymerised by a cryogelation process that allowed us to reach scaffold fabrication up to millimeter size and solve the main problems related to the large size muscle tissue constructs. (1) By incorporating carbon nanotubes (CNT), we can improve the electrical properties of the scaffold, thereby enhancing tissue maturation when applying an electric pulse stimulus (EPS). (2) We have fabricated an anisotropic internal three-dimensional microarchitecture with good pore distribution and highly aligned morphology to enhance the cell alignment, cell fusion and myotube formation. With this set up, we were able to generate a fully functional skeletal muscle tissue using a combination of EPS and our doped-biocomposite scaffold and obtain a mature tissue on the millimeter scale. We also characterized the pore distribution, swelling, stiffness and conductivity of the scaffold. Moreover, we proved that the cells were viable and could fuse in three-dimensional (3D) functional myotubes throughout the scaffold. In conclusion, we fabricated a biocompatible and customizable scaffold for 3D cell culture suitable for a wide range of applications such as organ-on-a-chip, drug screening, transplantation and disease modelling.

Aptamers Increase Biocompatibility and Reduce the Toxicity of Magnetic Nanoparticles Used in Biomedicine

Aptamer-based approaches are very promising tools in nanomedicine. These small single-stranded DNA or RNA molecules are often used for the effective delivery and increasing biocompatibility of various therapeutic agents. Recently, magnetic nanoparticles (MNPs) have begun to be successfully applied in various fields of biomedicine. The use of MNPs is limited by their potential toxicity, which depends on their biocompatibility. The functionalization of MNPs by ligands increases biocompatibility by changing the charge and shape of MNPs, preventing opsonization, increasing the circulation time of MNPs in the blood, thus shielding iron ions and leading to the accumulation of MNPs only in the necessary organs. Among various ligands, aptamers, which are synthetic analogs of antibodies, turned out to be the most promising for the functionalization of MNPs. This review describes the factors that determine MNPs’ biocompatibility and affect their circulation time in the bloodstream, biodistribution in organs and tissues, and biodegradation. The work also covers the role of the aptamers in increasing MNPs’ biocompatibility and reducing toxicity.

Hydrogels as Potential Nano-, Micro- and Macro-Scale Systems for Controlled Drug Delivery

This review is an extensive evaluation and essential analysis of the design and formation of hydrogels (HGs) for drug delivery. We review the fundamental principles of HGs (their chemical structures, physicochemical properties, synthesis routes, different types, etc.) that influence their biological properties and medical and pharmaceutical applications. Strategies for fabricating HGs with different diameters (macro, micro, and nano) are also presented. The size of biocompatible HG materials determines their potential uses in medicine as drug carriers. Additionally, novel drug delivery methods for enhancing treatment are discussed. A critical review is performed based on the latest literature reports.

The rationale and emergence of electroconductive biomaterial scaffolds in cardiac tissue engineering

The human heart possesses minimal regenerative potential, which can often lead to chronic heart failure following myocardial infarction. Despite the successes of assistive support devices and pharmacological therapies, only a whole heart transplantation can sufficiently address heart failure. Engineered scaffolds, implantable patches, and injectable hydrogels are among the most promising solutions to restore cardiac function and coax regeneration; however, current biomaterials have yet to achieve ideal tissue regeneration and adequate integration due a mismatch of material physicochemical properties. Conductive fillers such as graphene, carbon nanotubes, metallic nanoparticles, and MXenes and conjugated polymers such as polyaniline, polypyrrole, and poly(3,4-ethylendioxythiophene) can possibly achieve optimal electrical conductivities for cardiac applications with appropriate suitability for tissue engineering approaches. Many studies have focused on the use of these materials in multiple fields, with promising effects on the regeneration of electrically active biological tissues such as orthopedic, neural, and cardiac tissue. In this review, we critically discuss the role of heart electrophysiology and the rationale toward the use of electroconductive biomaterials for cardiac tissue engineering. We present the emerging applications of these smart materials to create supportive platforms and discuss the crucial role that electrical stimulation has been shown to exert in maturation of cardiac progenitor cells.

Use of nanoparticles in skeletal tissue regeneration and engineering

Bone and osteochondral defects represent one of the major causes of disabilities in the world. Derived from traumas and degenerative pathologies, these lesions cause severe pain, joint deformity, and loss of joint motion. The standard treatments in clinical practice present several limitations. By producing functional substitutes for damaged tissues, tissue engineering has emerged as an alternative in the treatment of defects in the skeletal system. Despite promising preliminary clinical outcomes, several limitations remain. Nanotechnologies could offer new solutions to overcome those limitations, generating materials more closely mimicking the structures present in naturally occurring systems. Nanostructures comparable in size to those appearing in natural bone and cartilage have thus become relevant in skeletal tissue engineering. In particular, nanoparticles allow for a unique combination of approaches (e.g. cell labelling, scaffold modification or drug and gene delivery) inside single integrated systems for optimized tissue regeneration. In the present review, the main types of nanoparticles and the current strategies for their application to skeletal tissue engineering are described. The collection of studies herein considered confirms that advanced nanomaterials will be determinant in the design of regenerative therapeutic protocols for skeletal lesions in the future.

Nanostructured Materials Based on Noble Metals for Advanced Biological Applications

This special issue focuses on highlighting the progress of last decade regarding the new nanostructured materials based on noble metals, especially gold and silver. Innovative preparations, functionalizations, and characterizations of these nanomaterials are investigated. Moreover, biotechnological applications, and advanced uses of these compounds for environmental sensing are reported. In particular gold and silver nanomaterials are widely studied due to their high stability, amazing chemical–physical features and, for silver, marked antibacterial properties. It is also hoped that the current special issue will encourage multidisciplinary research on noble metal nanomaterials, expanding the range of potential biological applications. This must be associated with improvements in synthetic methods and with economic feasibility studies of the proposed processes, also exploring the ecotoxicological aspects.