Adnan Haider

Preparation of Silver Nanoparticles and Their Industrial and Biomedical Applications: A Comprehensive Review

Silver nanoparticles (Ag-NPs) have diverted the attention of the scientific community and industrialist itself due to their wide range of applications in industry for the preparation of consumer products and highly accepted application in biomedical fields (especially their efficacy against microbes, anti-inflammatory effects, and wound healing ability). The governing factor for their potent efficacy against microbes is considered to be the various mechanisms enabling it to prevent microbial proliferation and their infections. Furthermore a number of new techniques have been developed to synthesize Ag-NPs with controlled size and geometry. In this review, various synthetic routes adapted for the preparation of the Ag-NPs, the mechanisms involved in its antimicrobial activity, its importance/application in commercial as well as biomedical fields, and possible application in future have been discussed in detail.

Nanofibrous scaffolds in biomedical applications.

Nanofibrous scaffolds are artificial extracellular matrices which provide natural environment for tissue formation. In comparison to other forms of scaffolds, the nanofibrous scaffolds promote cell adhesion, proliferation and differentiation more efficiently due to having high surface to volume ratio. Although scaffolds for tissue engineering have been fabricated by various techniques but electrospun nanofibrous scaffolds have shown great potential in the fields of tissue engineering and regeneration. This review highlights the applications and importance of electrospun nanofibrous scaffolds in various fields of biomedical applications ranging from drug delivery to wound healing. Attempts have also been made to highlights the advantages and disadvantages of nanofirbous scaffolds fabricated for biomedical applications using technique of electrospinning. The role of various factors controlling drug distribution in electrospun nanofibrous scaffolds is also discussed to increase the therapeutic efficiency of nanofibrous scaffolds in wound healing and drug delivery applications.

Morphological Effects of HA on the Cell Compatibility of Electrospun HA/PLGA Composite Nanofiber Scaffolds

Tissue engineering is faced with an uphill challenge to design a platform with appropriate topography and suitable surface chemistry, which could encourage desired cellular activities and guide bone tissue regeneration. To develop such scaffolds, composite nanofiber scaffolds of nHA and sHA with PLGA were fabricated using electrospinning technique. nHA was synthesized using precipitation method, whereas sHA was purchased. The nHA and sHA were suspended in PLGA solution separately and electrospun at optimized electrospinning parameters. The composite nanofiber scaffolds were characterized by FE-SEM, EDX analysis, TEM, XRD analysis, FTIR, and X-ray photoelectron. The potential of the HA/PLGA composite nanofiber as bone scaffolds in terms of their bioactivity and biocompatibility was assessed by culturing the osteoblastic cells onto the composite nanofiber scaffolds. The results from in vitro studies revealed that the nHA/PLGA composite nanofiber scaffolds showed higher cellular adhesion, proliferation, and enhanced osteogenesis performance, along with increased Ca+2 ions release compared to the sHA/PLGA composite nanofiber scaffolds and pristine PLGA nanofiber scaffold. The results show that the structural dependent property of HA might affect its potential as bone scaffold and implantable materials in regenerative medicine and clinical tissue engineering.

Recent advances in the synthesis, functionalization and biomedical applications of hydroxyapatite: a review

Hydroxyapatite (HA) is a member of the Ca apatite family. It resembles natural bone in both structure and chemical composition. HA, owing to its bioactive and biocompatible properties, has been commonly used as an implant material in bone tissue regeneration (osteogenesis), and as a drug carrier in drug and gene delivery systems. With the advances in research on the use of HA, an increasing number of researchers are exploring new synthesis processes, characterization and functionalization techniques for HA and its potential role in various fields such as magnetic resonance, controlled delivery of therapeutic drugs, cell separation, bio imaging and treatment of hyperthermia. Therefore, in this review, we highlight the composition of HA, the advances in its synthesis processes, characterization and functionalization techniques, and its importance in the biomedical field in general, and in emerging areas such as implants, drug delivery, composites, coatings, and ceramic materials in particular. The idea behind writing this review was to collect and summarize the most recent studies involving HA, so that researchers can easily find HA-related information compiled in a single document. In addition, we have also discussed the future prospects of HA. We believe that readers will not only conveniently obtain the desired information from this review, but will also get to the core of the information more easily.

PLGA/nHA hybrid nanofiber scaffold as a nanocargo carrier of insulin for accelerating bone tissue regeneration

The development of tissue engineering in the field of orthopedic surgery is booming. Two fields of research in particular have emerged: approaches for tailoring the surface properties of implantable materials with osteoinductive factors as well as evaluation of the response of osteogenic cells to these fabricated implanted materials (hybrid material). In the present study, we chemically grafted insulin onto the surface of hydroxyapatite nanorods (nHA). The insulin-grafted nHAs (nHA-I) were dispersed into poly(lactide-co-glycolide) (PLGA) polymer solution, which was electrospun to prepare PLGA/nHA-I composite nanofiber scaffolds. The morphology of the electrospun nanofiber scaffolds was assessed by field emission scanning electron microscopy (FESEM). After extensive characterization of the PLGA/nHA-I and PLGA/nHA composite nanofiber scaffolds by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectrometry (EDS), and transmission electron microscopy (TEM), the PLGA/nHA-I and PLGA/nHA (used as control) composite nanofiber scaffolds were subjected to cell studies. The results obtained from cell adhesion, alizarin red staining, and Von Kossa assay suggested that the PLGA/nHA-I composite nanofiber scaffold has enhanced osteoblastic cell growth, as more cells were proliferated and differentiated. The fact that insulin enhanced osteoblastic cell proliferation will open new possibilities for the development of artificial scaffolds for bone tissue regeneration.

Adsorption kinetic and isotherm of methylene blue, safranin T and rhodamine B onto electrospun ethylenediamine-grafted-polyacrylonitrile nanofibers membrane

AbstractEDA-g-PAN NFs membrane was prepared via electrospinning and chemical grafting techniques. Grafting (64%) with no change in the physical nature and colour was confirmed by FT-IR spectra. Adsorption kinetics of methylene blue (MB), rhodamine B (RB) and safranin T (ST) dyes onto PAN and EDA-g-PAN NFs membranes showed equilibrium time of around ~60 min. The adsorption kinetic followed pseudo-second-order model and intraparticle diffusion was not the only rate-limiting step. The adsorption data for the dyes fitted well to Langmuir and Freundlich equations. The order of adsorption capacity (qmax) obtained from Langmuir plot was: MB (94.07 mg/g) < ST (110.62 mg/g) < RB (138.69 mg/g). These values are more than most of the values reported in literature.

Antibacterial activity and cytocompatibility of PLGA/CuO hybrid nanofiber scaffolds prepared by electrospinning

The PLGA/CuO hybrid nanofibers scaffolds were prepared via electrospinning technique. The presence of CuO in the PLGA scaffolds was confirmed by transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). The scaffolds were subjected to various antibacterial and cytobiocompatibility tests. The results not only showed excellent adhesion, proliferation, and viability (live/dead staining) for fibroblastic cells but also revealed that PLGA/CuO hybrid nanofiber scaffolds inhibited both Gram-positive and Gram-negative bacterial growth. The mechanism of the antibacterial activity was concluded to be based on the CuO nanoparticles and Cu++ ions release. It is, therefore, evaluated that PLGA/CuO hybrid nanofiber scaffolds can be a useful candidate for wound dressing.

Photoinduced development of antibacterial materials derived from isosorbide moiety.

A straightforward method for immobilizing in situ generated silver nanoparticles on the surface of a photoactivable isosorbide-derived monomer is developed with the objective to design a functional material having antibacterial properties. The photoinduced thiol-ene mechanism involved in these syntheses is described by the electron spin resonance/spin trapping technique. The resulting materials with or without silver nanoparticles (Ag NPs) were used as films or as coatings on glass substrate. The surface of the synthesized materials was characterized by X-ray photoelectron spectroscopy and scanning electron microscopy, and their thermal and mechanical properties were evaluated by dynamic-mechanical thermal tests, differential scanning calorimetry, thermogravimetric analyses, along with pencil hardness, nanoindentation, and scratch resistance tests. The photoinduced formation of Ag NPs is also confirmed by UV spectrophotometry. Finally, a primary investigation demonstrates the antibacterial properties of the isosorbide-derived material against Staphylococcus aureus and Escherichia coli, as well as its cytocompatibility toward NIH 3T3 fibroblastic cells.

BMP-2 Grafted nHA/PLGA Hybrid Nanofiber Scaffold Stimulates Osteoblastic Cells Growth.

Biomaterials play a pivotal role in regenerative medicine, which aims to regenerate and replace lost/degenerated tissues or organs. Natural bone is a hierarchical structure, comprised of various cells having specific functions that are regulated by sophisticated mechanisms. However, the regulation of the normal functions in damaged or injured cells is disrupted. In order to address this problem, we attempted to artificially generate a scaffold for mimicking the characteristics of the extracellular matrix at the nanoscale level to trigger osteoblastic cell growth. For this purpose, we have chemically grafted bone morphogenetic protein (BMP-2) onto the surface of L-glutamic acid modified hydroxyapatite incorporated into the PLGA nanofiber matrix. After extensive characterization using various spectroscopic techniques, the BMP-g-nHA/PLGA hybrid nanofiber scaffolds were subjected to various in vitro cytocompatibility tests. The results indicated that BMP-2 on BMP-g-nHA/PLGA hybrid nanofiber scaffolds greatly stimulated osteoblastic cells growth, contrary to the nHA/PLGA and pristine PLGA nanofiber scaffold, which are used as control. These results suggest that BMP-g-nHA/PLGA hybrid nanofiber scaffold can be used as a nanodrug carrier for the controlled and targeted delivery of BMP-2, which will open new possibilities for enhancing bone tissue regeneration and will help in the treatment of various bone-related diseases in the future.

Toxic Effects of Nanomaterials

Description: Toxic Effects of Nanomaterials provides an authoritative work of international experts in the field of nanotoxicology spanning 8 chapters. A key feature of the e-book is a broad coverage of phytotoxicity of nanoparticles, which is largely neglected in many texts. The first couple of chapters of this book deal with the toxicity of nanoparticles in plants. This is followed by a discussion on the toxicities of iron oxide, titanium oxide and silicon oxide nanoparticles. Next, the volume provides a comprehensive review of methodologies used in nanotoxicology surveys. The concluding chapters highlight the risks associated with the use of nanoparticles and the environmental impact of nanomaterials. Such a broad coverage of nanotoxicology renders this book highly beneficial to the scientists from multidisciplinary areas including nanotechnologists, toxicologists, pharmacologists, environmental chemists and biomedical scientists. This book would equally be useful for the individuals advocating for sustainable use of nanotechnology.