Attributes of Nanomaterials and Nanotopographies for Improved Bone Tissue Engineering and Regeneration.

Bone tissue engineering (BTE) is a multidisciplinary area that can solve the limitation of conventional grafting methods by developing viable and biocompatible bone replacements. The three essential components of BTE, i.e., Scaffold material and Cells and Growth factors altogether, facilitate support and guide for bone formation, differentiation of the bone tissues, and enhancement in the cellular activities and bone regeneration. However, there is a scarcity of the appropriate materials that can match the mechanical property as well as functional similarity to native tissue, considering the bone as hard tissue. In such scenarios, nanotechnology can be leveraged upon to achieve the desired aspects of BTE, and that is the key point of this review article. This review article examines the significant areas of nanotechnology research that have an impact on regeneration of bone: (a) scaffold with nanomaterials helps to enhance physicochemical interactions, biocompatibility, mechanical stability, and attachment; (b) nanoparticle-based approaches for delivering bioactive chemicals, growth factors, and genetic material. The article begins with the introduction of components and healing mechanisms of bone and the factors associated with them. The focus of this article is on the various nanotopographies that are now being used in scaffold formation, by describing how they are made, and how these nanotopographies affect the immune system and potential underlying mechanisms. The advantages of 4D bioprinting in BTE by using nanoink have also been mentioned. Additionally, we have investigated the importance of an in silico approach for finding the interaction between drugs and their related receptors, which can help to formulate suitable systems for delivery. This review emphasizes the role of nanoscale approach and how it helps to increase the efficacy of parameters of scaffold as well as drug delivery system for tissue engineering and bone regeneration.

Nanofiber-Based Systems for Stimuli-Responsive and Dual Drug Delivery: Present Scenario and the Way Forward.

Drug delivery and delivery systems are among the most important research disciplines today, and the relevance of nanofibers in achieving the appropriate release profile at specified sites for increased therapeutic advantages cannot be understated. Nanofiber-based drug delivery systems are fabricated and modified using a range of methods that entail a variety of factors and processes; tuning of these allows control of the drug release such as targeted, extended, multistage, and stimuli-responsive release. We explore nanofiber-based drug delivery systems from the most recent accessible literature, focusing on materials, techniques, modifications, drug release, applications, and challenges. This review offers a thorough assessment of the current and future potential of nanofiber-based drug delivery systems, with a particular emphasis on their capabilities in stimuli-responsive and dual drug delivery. The review begins with an introduction to the important characteristics of nanofibers that are useful in drug delivery applications, followed by materials and synthesis procedures for various types of nanofibers, as well as their practicality and scalability. The review then focuses on and explores the modification and functionalization strategies of nanofibers as essential features for regulating the applications of nanofibers in drug loading, transport, and release. Finally, this review investigates the range of nanofiber-based drug delivery systems in satisfying the current requirements by pointing out the areas that need improvement, followed by critical analysis, and offers probable solutions.

Flexible and free-standing bacterial cellulose derived cathode host and separator for lithium-sulfur batteries.

This study demonstrates flexible, ultra-high rate, and long cycle life lithium­sulfur batteries using bacterial cellulose (BC) derived cathode host as well as separator. The work also includes a new strategy to use active sulfur in the form of catholyte added directly to the electrolyte for improved sulfur utilization. The fabricated LiS cell with carbonized bacterial cellulose (CBC) as a cathode host and BC as a separator (CBC@BC) delivers an impressive capacity of 740 mAh g-1 at 1C. It retains a capacity of 310 mAh g-1 even at an ultra-high rate of 4C. To have commercial adoption of CBC@BC, we tested LiS cells with a high areal loading of 5 mg cm-2. The cell shows promising electrochemical performance for 500 cycles with a capacity retention of 82 %. Furthermore, first-principle calculations are performed to understand the interaction of soluble lithium-polysulfides with bacterial cellulose-derived material.

Antimicrobial surfaces: a review of synthetic approaches, applicability and outlook.

The rapid spread of microorganisms such as bacteria, fungi, and viruses can be extremely detrimental and can lead to seasonal epidemics or even pandemic situations. In addition, these microorganisms may bring about fouling of food and essential materials resulting in substantial economic losses. Typically, the microorganisms get transmitted by their attachment and growth on various household and high contact surfaces such as doors, switches, currency. To prevent the rapid spread of microorganisms, it is essential to understand the interaction between various microbes and surfaces which result in their attachment and growth. Such understanding is crucial in the development of antimicrobial surfaces. Here, we have reviewed different approaches to make antimicrobial surfaces and correlated surface properties with antimicrobial activities. This review concentrates on physical and chemical modification of the surfaces to modulate wettability, surface topography, and surface charge to inhibit microbial adhesion, growth, and proliferation. Based on these aspects, antimicrobial surfaces are classified into patterned surfaces, functionalized surfaces, superwettable surfaces, and smart surfaces. We have critically discussed the important findings from systems of developing antimicrobial surfaces along with the limitations of the current research and the gap that needs to be bridged before these approaches are put into practice. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10853-021-06404-0.

Ex-situ modification of bacterial cellulose for immediate and sustained drug release with insights into release mechanism.

The release of drug from bacterial cellulose (BC) is tuned to achieve immediate and controlled delivery by using two drying strategies: freeze-drying and oven-drying. Diclofenac sodium (DCF), a hydrophilic drug, was used as the model drug and was loaded in oven-dried BC (BC-OD-DCF) and freeze-dried BC (BC-FD-DCF) to obtain sustained release and burst release, respectively. BC dried by the two methods were characterized and found to possess different structures and morphologies. The crystallinity was found to be higher for BC-OD (86 % for BC-OD and 79 % for BC-FD) while BC-FD offered higher porosity (92 % for BC-FD and 75 % for BC-OD), higher specific surface area (85 m2/g for BC-FD and 35 m2/g for BC-OD) and pore size, which altogether affects the matrix swellability, drug loading and release behaviour. The mathematical modelling of drug release kinetics supports diffusion-driven first-order release from BC-FD-DCF whereas release from BC-OD-DCF shows a super case II transport, where the buffer front travels slowly into the denser oven-dried matrix leading to a controlled release of the drug. The correlation between swelling and cumulative drug release is also discussed.

Small angle X-ray study of cellulose macromolecules produced by tunicates and bacteria.

The organisation of poly-glucan chains into cellulose macromolecular microfibrils has been studied using small angle X-ray scattering (SAXS). Three kinds of cellulose - bacterial cellulose (BC), nata-de-coco (NdC) (food grade bacterial cellulose) and tunicate cellulose (TC) have been investigated. Given the large ambiguity in literature on the microfibril dimensions owing to different methods and data analysis strategies, a method to extract dimensions of cellulose microfibrils using SAXS has been shown, which was found to be consistent across all the samples. The results have been verified with microscopy data. Two populations of microfibrils with different cross-section dimensions were identified. The dimensions of the rectangular cross-sections of BC were found to be 32nm by 16nm and 21nm by 10nm. The dimensions for NdC were calculated to be 25nm×8nm and 14nm×6nm and that for TC were determined to be 25nm×10nm and 15nm×8nm.

Origin of chiral interactions in cellulose supra-molecular microfibrils.

The formation of a chiral-nematic phase from cellulose nanowhiskers has been frequently reported in the literature. The most popular theory used to explain the chiral interactions is that of twisted morphology of cellulose nanowhiskers. Two possible origins of twist have been suggested: the intrinsic chirality of cellulose chains and result of interaction of chiral surfaces. High resolution SEM and AFM have been used to locate twists in cellulose microfibrils and nanowhiskers. The origin of the twisted morphology in cellulose microfibrils has been studied with reference to the protein aggregation theory.