Naveed Ahmed

Theranostic applications of nanoparticles in cancer

Nanoparticles are the moieties that have undergone the most investigation in recent years for biomedical applications. They are applied in the field of oncology in the same way as in other branches of biomedical nanotechnology. Regarding cancer, nanoparticles, and especially magnetic nanoparticles, are studied for diagnosis, drug delivery, gene delivery, bioseparation, hyperthermia, phototherapy, chemotherapy, imaging mechanisms, among other uses. Different techniques are used to prepare multifunctional nanoparticles and modify nanoparticle surfaces required for different applications. This review focuses on the basic theranostic approach, the different materials used in theranostics, theranostic applications and future directions based on recent developments in these areas.

On the MHD flow of a second grade fluid in a porous channel

The steady flow of a second grade fluid in a porous channel is considered. The constitutive equations are those used for a second grade fluid. The fluid is electrically conducting in the presence of a uniform magnetic field applied in the transverse direction to the flow. It is shown that an analytical solution is possible by employing a homotopy analysis method (HAM). The convergence of the obtained solution is also taken into account. Assessment for the influence of various parameters of interest on the velocity is undertaken.

Modified double emulsion process as a new route to prepare submicron biodegradable magnetic/polycaprolactone particles for in vivo theranostics

A modified double emulsion evaporation method was devised to encapsulate active ingredients to be used for theranostic purposes. In comparison with classical double emulsion methods, the solvents used for this modified method are miscible. Aqueous and organic ferrofluids having different solid contents of iron oxide nanoparticles were prepared by the co-precipitation method. Different materials were screened for the preparation of biodegradable and biocompatible nanoparticles via this new modified double emulsion evaporation method. Factors affecting the final particle size were investigated by encapsulating a hydrophilic model drug that permitted us to prepare a recipe using polycaprolactone (PCL) as polymer, dichloromethane (DCM) as organic solvent and polyvinyl alcohol (PVA) as stabilizing agent. The characterization of aqueous and organic ferrofluids alone, Stilbene and iron oxide loaded nanoparticles was done by studying particle size, size distribution, zeta potential and morphology, the magnetic properties and chemical composition. All the characterization results showed that the process is praiseworthy for encapsulation of iron oxide nanoparticles (in both aqueous and organic medium) along with an active ingredient for theranostic purposes with a final size of about 300 nm.

Advances in Shape Memory Polyurethanes and Composites: A Review

Polyurethanes are synthetic smart materials having exquisite property to regain original shape from temporary shape when an external force (heat, light, electricity, and entropy driven deformation) is applied. Shape memory polyurethanes have ability to replace shape memory alloys due to cut-rate, easy manufacturing, programing, and high shape recovery ratio. The review focused on polyurethane types exhibiting shape memory effect and various categories of shape memory effects in polyurethane. Moreover, compound structure, modeling structure, applications, and related synthetic methods for shape memory polyurethanes are discussed. The strategies for induction of cross-linking and post cross-linking at high, medium, and low temperature are surveyed. GRAPHICAL ABSTRACT

Recent applications of PLGA based nanostructures in drug delivery

Over the years, issues associated with non-biodegradable polymers have paved the way for biodegradable polymers in the domain of pharmaceutical and biomedical sciences. Poly (lactic-co-glycolic acid) (PLGA) is considered one of the most thrivingly synthesized biodegradable polymers. To formulate polymeric nanostructures, PLGA has attained noteworthy attention due to its controllable properties, complete biodegradability and biocompatibility, well defined formulation techniques and easy processing. This review focuses on fabrication techniques of PLGA based nanostructures and their advanced biomedical applications covering drug delivery and in-vivo imaging. Researchers have extensively investigated the potential of PLGA nanoparticles for target specific and controlled delivery of various micro and macromolecules including drugs, peptides, proteins, monoclonal antibodies, growth factors and DNA in multifarious biomedical applications like neurodegenerative and cardiovascular diseases, inflammatory disorders, cancer and other dreadful health disorders. Beside this, PLGA is being employed for theranostic purposes where polymer is attached with contrast agents for imaging-directed chemo or photo thermal combinative therapy. Multifunctional PLGA nanostructures have given an avenue to future nanomedicine to consider simultaneous drug delivery, molecular imaging, and real-time monitoring of therapeutic response. This review describes the applications of PLGA in drug delivery revealing its current progress and direction for future research.

Shape memory properties of electrically conductive multi-walled carbon nanotube-filled polyurethane/modified polystyrene blends:

Shape memory polyurethanes are synthetic materials with great potential to respond to external stimulus. Desired properties of shape memory polyurethanes can be achieved by blending with other polymers or varying the hard and soft segments. In this study, structure, morphology, mechanical, thermal and electrical conductivity properties of a shape memory blend reinforced with multi-walled carbon nanotube were investigated. One blend component was polyethylene glycol and toluene diisocyanate polyurethane, and the second component was either polystyrene or nitro-functional or amino-functional. The fundamental chemical and physical linkages were confirmed by Fourier transform infrared spectroscopy. Field emission scanning electron microscopic images demonstrated the generation of polyurethane–polystyrene interpenetrating polymer network over multi-walled carbon nanotube surface. The tensile strength and modulus were found to increase systematically with increasing filler content in all series and was higher for polyurethane/polystyrene amino-functional/multi-walled carbon nanotube composites. The stress-bearing capacity and mechanical properties were enhanced due to a matrix made up of two different chemically interlinked polymers. On the whole, using amino-functional polystyrene showed better physical and shape memory properties. Electrical conductivity was superior for composites with polystyrene amino-functional matrix, compared with neat blend and other composite. The polyurethane/polystyrene amino-functional/multi-walled carbon nanotube 0.5 electrical conductivity tested at 1.08u2009Su2009cm−1. The polyurethane/polystyrene amino-functional/multi-walled carbon nanotube composites showed remarkable thermally triggered shape memory behavior to the extent of 95%. Electric field-triggered shape recovery of the polyurethane/polystyrene amino-functional/multi-walled carbon nanotube sample was found to be 96%. The synergetic effect of the fine electrical conductivity and high mechanical strength renders the composites as high-performance shape memory materials.

Synthesis of Ag-NPs impregnated cellulose composite material: its possible role in wound healing and photocatalysis

Cellulose is the natural biopolymer normally used as supporting agent with enhanced applicability and properties. In present study, cellulose isolated from citrus waste is used for silver nanoparticles (Ag-NPs) impregnation by a simple and reproducible method. The Ag-NPs fabricated cellulose (Ag-Cel) was characterised by powder X-rays diffraction, Fortier transform infrared spectroscopy and scanning electron microscopy. The thermal stability was studied by thermo-gravimetric analysis. The antibacterial activity performed by disc diffusion assay reveals good zone of inhibition against Staphylococcus aureus and Escherichia coli by Ag-Cel as compared Ag-NPs. The discs also displayed more than 90% reduction of S. aureus culture in broth within 150u2005min. The Ag-Cel discs also demonstrated minor 2,2-diphenyl 1-picryl-hydrazyl radical scavenging activity and total reducing power ability while moderate total antioxidant potential was observed. Ag-Cel effectively degrades methylene-blue dye up to 63.16% under sunlight irradiation in limited exposure time of 60u2005min. The Ag-NPs impregnated cellulose can be effectively used in wound dressing to prevent bacterial attack and scavenger of free radicals at wound site, and also as filters for bioremediation and wastewater purification.

Formulation and In Vitro Characterization of Thiolated Buccoadhesive Film of Fluconazole.

The present work is focused on the development of thiolated film for fluconazole buccal delivery. To this end, unmodified polymers chitosan and sodium carboxymethylcellulose (NaCMC) backbone was covalently modified by thioglycolic acid (TGA) and cysteine, respectively. The thiolated buccoadhesive film was evaluated in terms of thickness, weight uniformity, water-uptake capacity, drug content, and release patterns. Moreover, mucoadhesion profile was investigated on buccal mucosa. The resulting chitosan–TGA and NaCMC–cysteine conjugates displayed 171u2009±u200913 and 380u2009±u200919xa0μmol thiol groups per gram of polymer (meanu2009±u2009SD; nu2009=u20093), respectively. The water binding capacity of the thiolated film was significantly ∼2-fold higher (pu2009<u20090.05) as compared to unmodified film. The obtained thiolated film displayed 5.8-fold higher mucoadhesive properties compared with corresponding film. Controlled release of drugs from film was observed over 8xa0h. The transport of fluconazole across excised buccal mucosa was enhanced up to 17-fold in comparison with fluconazole applied in buffer. Based on these findings, thiolated film seems to be promising for fluconazole buccal delivery.

In vitro MRI of biodegradable hybrid (iron oxide/polycaprolactone) magnetic nanoparticles prepared via modified double emulsion evaporation mechanism

Hybrid magnetic particles are being applied in biomedical field for various aims. One of such aim is use of magnetic particles for diagnostic purposes especially in imaging mechanisms. In vitro magnetic resonance imaging of biodegradable hybrid (iron oxide/polycaprolactone) magnetic nanoparticles is carried out. Hybrid magnetic nanoparticles were prepared by encapsulation of iron oxide nanoparticles (IONPs) in polycaprolactone (PCL) via modified double emulsion evaporation technique. Both the IONPs and hybrid nanoparticles were characterized for their sizes, zeta potential, microscopic, thermogravimetric, and magnetism. Prepared particles were investigated for T1 and T2 weighted enhancement of contrast in vitro in water. A comparison of the prepared particles was done with commercially available Gadolinium for the contrast efficiency in MRI. Results showed the prepared particles exhibited nanosize range, good morphology and superparamagnetic character. The enhancement in the MRI contrast of the prepared particles was observed and found to depend on type of the prepared particles. Comparison of the MRI contrast of the prepared particles with the commercial Gadolinium suggests their usefulness as T2 contrast agent.

Lipid polymer hybrid carrier systems for cancer targeting: A review

ABSTRACT Cancer has been the most deleterious disease since few decades and its prevalence is increasing day by day. Scientists have developed many novel carrier systems to modify the delivery of anticancer drugs specifically toward the cancer sites. Liposomes seemed to be the particles of choice to carry anticancer drugs owing to their biomembrane-friendly structure. However, poor stability and storage problems remain a drawback. Polymeric nanoparticles (PNPs) offer their rigid structure making controlled release of drugs possible. PNPs also maintain their integrity for a longer period of time. Recently, the benefits of the two carrier systems mentioned above have been combined into a single hybrid carrier system, i.e., lipid polymer hybrid nanoparticles. Such a setting makes a useful carrier system taking advantages of both the counterparts and minimizing their limitations at the same time. In this review, special types of lipid and polymer hybrid structures are discussed in detail. Also the methods of preparation along with controlling formulation parameters have been discussed. Various targeting moieties have been enlisted along with their mechanisms of active targeting. These moieties can be functionalized onto the surfaces of these hybrid particles. Special focus has been given to the colorectal cancer, throwing light upon its prevalence and already available treatment options. Lipid polymer hybrid nanoparticles enable the researchers to formulate a carrier system that will be able to provide targeted anticancer drug delivery. GRAPHICAL ABSTRACT