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The drug delivery system enables the release of the active pharmaceutical ingredient to achieve a desired therapeutic response. Conventional drug delivery systems (tablets, capsules, syrups, ointments, etc.) suffer from poor bioavailability and fluctuations in plasma drug level and are unable to achieve sustained release. Without an efficient delivery mechanism, the whole therapeutic process can be rendered useless. Moreover, the drug has to be delivered at a specified controlled rate and at the target site as precisely as possible to achieve maximum efficacy and safety. Controlled drug delivery systems are developed to combat the problems associated with conventional drug delivery. There has been a tremendous evolution in controlled drug delivery systems from the past two decades ranging from macro scale and nano scale to intelligent targeted delivery. The initial part of this review provides a basic understanding of drug delivery systems with an emphasis on the pharmacokinetics of the drug. It also discusses the conventional drug delivery systems and their limitations. Further, controlled drug delivery systems are discussed in detail with the design considerations, classifications and drawings. In addition, nano-drug delivery, targeted and smart drug delivery using stimuli-responsive and intelligent biomaterials is discussed with recent key findings. The paper concludes with the challenges faced and future directions in controlled drug delivery.

The improper disposal and informal processing of e-waste have raised serious concerns for the environment and human health worldwide. A variety of legislative frameworks have been implemented to regulate e-waste management and upcycling in order to prevent environmental pollution and adopt resource reuse. Current e-waste legislation in different countries mostly include restrictions on e-waste import/export, regulations for recycling specific categories of e-waste, and Extended Producer Responsibility (EPR). This article serves as a comprehensive commentary to weigh the advantages and drawbacks of the different e-waste legislation enforced around the world. Though each country’s e-waste legislation is enframed to address the country-specific problems, the legislation is mostly not holistic, leading to different management issues. A variety of e-waste management issues prevalent in most countries (with e-waste specific legislation) have been listed and categorized for better understanding of the status quo. Further, the article proposes a generic e-waste management model catering to requirements of countries around the world. The implementation of such a model for Europe, China, India, Japan, South Korea, Taiwan, and Australia has been illustrated to show that the model can suit both developed and developing countries with contrasting e-waste management issues. The challenges that would arise in implementing an effective legislation and mechanisms for overcoming these challenges have also been discussed. To conclude, the role of governing bodies in tackling the future e-waste problems has been highlighted. In total, the article promotes scaling up the feasibility and efficacy of the implementation of e-waste policies across the globe in the coming years.

Magnesium is a promising material. It has a remarkable mix of mechanical and biomedical properties that has made it suitable for a vast range of applications. Moreover, with alloying, many of these inherent properties can be further improved. Today, it is primarily used in the automotive, aerospace, and medical industries. However, magnesium has its own set of drawbacks that the industry and research communities are actively addressing. Magnesium’s rapid corrosion is its most significant drawback, and it dramatically impeded magnesium’s growth and expansion into other applications. This article reviews both the engineering and biomedical aspects and applications for magnesium and its alloys. It will also elaborate on the challenges that the material faces and how they can be overcome and discuss its outlook.

Although 3D printing was invented in 1984, it was not until recent years that it captured the imagination of everyone from industry experts to at-home hobbyists. Three-dimensional printing, also known as additive manufacturing or rapid prototyping, constructs an object by accumulating materials layer by layer. In recent years, 3D printing technology has been dramatically developed with respect to materials, printer, and process, which laid a foundation for 4D printing. Four-dimensional printing is the targeted evolution of the 3D-printed structure, concerning shape, property, and functionality. The object is produced by 3D printing firstly. Then, the object can self-deform, self-assemble, self-disassemble, self-repair, and change property or functionality over time when the external stimuli are imposed on it. This review mainly introduces the stimulus, types of shape-shifting behaviors, mechanisms of deformation, and applications of 4D printing.

Iron oxides are chemical compounds which have different polymorphic forms, including γ-Fe2O3 (maghemite), Fe3O4 (magnetite), and FeO (wustite). Among them, the most studied are γ-Fe2O3 and Fe3O4, as they possess extraordinary properties at the nanoscale (such as super paramagnetism, high specific surface area, biocompatible etc.), because at this size scale, the quantum effects affect matter behavior and optical, electrical and magnetic properties. Therefore, in the nanoscale, these materials become ideal for surface functionalization and modification in various applications such as separation techniques, magnetic sorting (cells and other biomolecules etc.), drug delivery, cancer hyperthermia, sensing etc., and also for increased surface area-to-volume ratio, which allows for excellent dispersibility in the solution form. The current methods used are partially and passively mixed reactants, and, thus, every reaction has a different proportion of all factors which causes further difficulties in reproducibility. Direct active and complete mixing and automated approaches could be solutions to this size- and shape-controlled synthesis, playing a key role in its exploitation for scientific or technological purposes. An ideal synthesis method should be able to allow reliable adjustment of parameters and control over the following: fluctuation in temperature; pH, stirring rate; particle distribution; size control; concentration; and control over nanoparticle shape and composition i.e., crystallinity, purity, and rapid screening. Iron oxide nanoparticle (IONP)-based available clinical applications are RNA/DNA extraction and detection of infectious bacteria and viruses. Such technologies are important at POC (point of care) diagnosis. IONPs can play a key role in these perspectives. Although there are various methods for synthesis of IONPs, one of the most crucial goals is to control size and properties with high reproducibility to accomplish successful applications. Using multiple characterization techniques to identify and confirm the oxide phase of iron can provide better characterization capability. It is very important to understand the in-depth IONP formation mechanism, enabling better control over parameters and overall reaction and, by extension, properties of IONPs. This work provides an in-depth overview of different properties, synthesis methods, and mechanisms of iron oxide nanoparticles (IONPs) formation, and the diverse range of their applications. Different characterization factors and strategies to confirm phase purity in the IONP synthesis field are reviewed. First, properties of IONPs and various synthesis routes with their merits and demerits are described. We also describe different synthesis strategies and formation mechanisms for IONPs such as for: wustite (FeO), hematite (α-Fe2O3), maghemite (ɤ-Fe2O3) and magnetite (Fe3O4). We also describe characterization of these nanoparticles and various applications in detail. In conclusion, we present a detailed overview on the properties, size-controlled synthesis, formation mechanisms and applications of IONPs.

Electrohydrodynamic (EHD) techniques refer to procedures that utilize electrostatic forces to fabricate fibers or particles of different shapes with sizes in the nano-range to a few microns through electrically charged fluid jet. Employing different techniques, such as blending, surface modification, and coaxial process, there is a great possibility of incorporating bioactive such molecules as drugs, DNA, and growth factors into the nanostructures fabricated via EHD techniques. By careful selection of materials and processing conditions, desired encapsulation efficiency as well as preserved bioactivity of the therapeutic agents can be achieved. The drug-loaded nanostructures produced can be applied via different routes, such as implantation, injection, and topical or oral administration for a wide range of disease treatment. Taking advantage of the recent developments in EHD techniques like the coaxial process or multilayered structures, individually controlled delivery of multiple drugs is achievable, which is of great demand in cancer therapy and growth-factor delivery. This review summarizes the most recent techniques and postmodification methods to fabricate electrospun nanofibers and electrosprayed particles for drug-delivery applications.

Commercially pure titanium and titanium alloys have been among the most commonly used materials for biomedical applications since the 1950s. Due to the excellent mechanical tribological properties, corrosion resistance, biocompatibility, and antibacterial properties of titanium, it is getting much attention as a biomaterial for implants. Furthermore, titanium promotes osseointegration without any additional adhesives by physically bonding with the living bone at the implant site. These properties are crucial for producing high-strength metallic alloys for biomedical applications. Titanium alloys are manufactured into the three types of α, β, and α + β. The scientific and clinical understanding of titanium and its potential applications, especially in the biomedical field, are still in the early stages. This review aims to establish a credible platform for the current and future roles of titanium in biomedicine. We first explore the developmental history of titanium. Then, we review the recent advancement of the utility of titanium in diverse biomedical areas, its functional properties, mechanisms of biocompatibility, host tissue responses, and various relevant antimicrobial strategies. Future research will be directed toward advanced manufacturing technologies, such as powder-based additive manufacturing, electron beam melting and laser melting deposition, as well as analyzing the effects of alloying elements on the biocompatibility, corrosion resistance, and mechanical properties of titanium. Moreover, the role of titania nanotubes in regenerative medicine and nanomedicine applications, such as localized drug delivery system, immunomodulatory agents, antibacterial agents, and hemocompatibility, is investigated, and the paper concludes with the future outlook of titanium alloys as biomaterials. Graphic abstract

Microbial polyhydroxyalkanoates (PHA) are proteinaceous storage granules ranging from 100 nm to 500 nm. Bacillus sp. serve as unique bioplastic sources of short-chain length and medium-chain length PHA showcasing properties such as biodegradability, thermostability, and appreciable mechanical strength. The PHA can be enhanced by adding functional groups to make it a more industrially useful biomaterial. PHA blends with hydroxyapatite to form nanocomposites with desirable features of compressibility. The reinforced matrices result in nanocomposites that possess significantly improved mechanical and thermal properties both in solid and melt states along with enhanced gas barrier properties compared to conventional filler composites. These superior qualities extend the polymeric composites’ applications to aggressive environments where the neat polymers are likely to fail. This nanocomposite can be used in different industries as nanofillers, drug carriers for packaging essential hormones and microcapsules, etc. For fabricating a bone scaffold, electrospun nanofibrils made from biocomposite of hydroxyapatite and polyhydroxy butyrate, a form of PHA, can be incorporated with the targeted tissue. The other methods for making a polymer scaffold, includes gas foaming, lyophilization, sol–gel, and solvent casting method. In this review, PHA as a sustainable eco-friendly NextGen biomaterial from bacterial sources especially Bacillus cereus, and its application for fabricating bone scaffold using different strategies for bone regeneration have been discussed.

From Germany’s Industry 4.0 mission to Made in China 2025 and Make in India mission to British Factory of the Future in 2050, digital manufacturing (DM) is promoting in the world’s major industrial countries as a technology foundation of the future manufacturing. At the same time, in the different segments of the DM realm, different forms of information technologies (IT) are flourishing such as the following: computer-aided manufacturing, robotics control in manufacturing, and process simulation. This paper is aimed to review the latest initiatives of DM in the leading universities and major industrial countries. Along with, a critical literature review of various initiatives in the area of DM-assisted hybrid additive manufacturing (DM-HAM) has also been carried out. DM-HAM seems to be very promising for next generation multi-operational manufacturing as it is time saving and economical. The highlights of this review will provide a guide for the upcoming research activities in the area of DM-HAM.