Controlled release of bioactive chemicals

This project has been concerned with the development of controlled release formulations of the herbicide atrazine and the pesticide chlorpyrifos. The results of both chemical and biological evaluation show that these controlled release formulations can significantly reduce leaching and therefore ground water pollution of atrazine without losing herbicidal potency in the early stages after application.

Lipid merging, protrusion and vesicle release triggered by shrinking/swelling of poly(N-isopropylacrylamide) microgel particles

Cell membrane changes its morphology during many physiological processes with the assistance of a solid support, such as the cytoskeleton, under an environmental stimulus. Here, a novel type of stimuli-responsive lipogel was fabricated, mimicking the changes of cell membrane. The lipogel was prepared from poly(N-isopropylacrylamide) (pNIPAM) microgel particle and phospholipid by a solvent-exchange method. The temperature dependent volume phase transition of pNIPAM triggers reversible transformation of the lipogel between a lipid vesicle-coated sun-like structure and a contracted hybrid sphere, through lipid merging and protrusion processes, respectively. By contrast, the salt induced pNIPAM phase transition leads to an irreversible vesicle release behaviour. The lipogel creates a unique platform for studying cell membrane behaviour and provides promising candidates in drug delivery and controlled release applications. © 2014 Elsevier B.V. All rights reserved.

Encapsulation of hydrophobic phthalocyanine with poly(N-isopropylacrylamide)/lipid composite microspheres for thermo-responsive release and photodynamic therapy

Phthalocyanine (Pc) is a type of promising sensitizer molecules for photodynamic therapy (PDT), but its hydrophobicity substantially prevents its applications. In this study, we efficiently encapsulate Pc into poly(N-isopropylacrylamide) (pNIPAM) microgel particles, without or with lipid decoration (i.e., Pc@pNIPAM or Pc@pNIPAM/lipid), to improve its water solubility and prevent aggregation in aqueous medium. The incorporation of lipid molecules significantly enhances the Pc loading efficiency of pNIPAM. These Pc@pNIPAM and Pc@pNIPAM/lipid composite microspheres show thermo-triggered release of Pc and/or lipid due to the phase transition of pNIPAM. Furthermore, in the in vitro experiments, these composite particles work as drug carriers for the hydrophobic Pc to be internalized into HeLa cells. After internalization, the particles show efficient fluorescent imaging and PDT effect. Our work demonstrates promising candidates in promoting the use of hydrophobic drugs including photosensitizers in tumor therapies. © 2014 by the authors.

Tailored mesoporous silica nanoparticles for controlled drug delivery: platform fabrication, targeted delivery, and computational design and analysis

Mesoporous silica nanoparticles (MSNs) are exceptionally promising drug carriers for controlled drug delivery systems because their morphology, pore structure, pore volume and pore size can be well tailored to obtain certain drug release profiles. Moreover, they possess the ability to specifically transport and deliver anti-cancer drugs when targeting molecules are properly grafted onto their surface. MSNs based drug delivery systems have the potential to revolutionize cancer therapy. This review provides a comprehensive overview of the fabrication, modification of MSNs and their applications in tumour-targeted delivery. In addition, the characterization and analysis of MSNs with computer aided strategies were described. The existing issues and future prospective concerning the applications of MSNs as drug carriers for controlled drug delivery systems were discussed.

Recent advances in nanoneurology for drug delivery to the brain

The drug development for neurodegenerative disorders are the major challenge to the science in 21st century. Many FDA approved drugs currently available in the market have limitations in crossing the blood brain barrier (BBB) owing to its complicated vasculature posed by the presence of specialized cells. Nanotechnology is an emerging interdisciplinary area, which have many applications including drug delivery. Nanocarrier drug delivery involves targeting drugs enclosed in a particular polymer and/or amphiphilic lipids. Controlled release, nanoplatform availability for combinatorial therapy and tissue specific targeting by using advanced technologies such as molecular Trojan horse (MTH) technology are the promises of nanotechnology. Different problems are associated with drug delivery
across the BBB. Some are mostly related to the structure of brain microvasculature system while the others are related to the nanomaterial
structure. Different strategies, such as using polymeric/solid lipid nanoparticles and surface modification of nanomaterial with surfactants
like polysorbates have been conducted to solve these limitations. Also, nanodrug formulations with double coatings have been designed for oral delivery of drugs to overcome reticulo-endothelial system and to improve their BBB permeability. It seems that the best choice of strategy and material could be achieved with regard to the physical and chemical structure of the drugs. The present review discusses the potential applications of nanotechnology for drug delivery across the BBB.

A novel nanoplatform for oral delivery of anti-cancer biomacromolecules

Oral administration of bio–macromolecules is an uphill task and the challenges from varying pH and enzymatic activity are difficult to overcome. In this regard, nanotechnology promises the new hope and offers advantages such as controlled release, target specific delivery, combinatorial therapy and many more. In this study, we demonstrate the formulation of a novel alginate enclosed, chitosan coated ceramic, anti cancer nano carrier (ACSC NC). These NC were loaded with multi functional anti cancer bovine lactoferrin (Lf), a natural milk based protein, for improvement of intestinal absorption, in order to develop a novel platform to carry anti cancer protein and/or peptides for oral therapy. Here we demonstrate the size, morphology, internalisation and release profiles of the nanoparticles (NC) under varying pH as perceived in human digestive system. We further determine the uptake of these particles by colon cancer cell lines by measuring the endocytosis and transcytosis of the NC. These NC can be used for future targeted protein/peptide or nucleic acid based drug delivery to treat difficult diseases including cancer.

Architecture of a biocompatible supramolecular material by supersaturation-driven fabrication of fiber network

The architecture of a biocompatible organogel formed by gelation of a small molecule organic gelator, N-lauroyl-l-glutamic acid di-n-butylamide, in isostearyl alcohol was investigated based on a supersaturation-driven crystallographic mismatch branching mechanism. By controlling the supersaturation of the system, the correlation length that determines the mesh size of the fiber network was finely tuned and the rheological properties of the gel were engineered. This approach is of considerable significance for many gel-based applications, such as controlled release of drugs that requires precise control of the mesh size. A direct cryo-transmission electron microscopy (TEM) imaging technique capable of preserving the network structure was used to visualize its nanostructure.

Nanotechnology based platforms for survivin targeted drug discovery

Introduction: Development of an effective, safe and targeted drug delivery system to fight cancer and other diseases is a prime focus in the area of drug discovery. The emerging field of nanotechnology has revolutionised the way cancer therapy and diagnosis is achieved primarily due to the recent advances in material engineering and drug availability. Further, the recognition of the crucial role played by anti-apoptotic proteins such as survivin, has initiated the development of therapeutics that can target this protein as an attempt to develop alternative cancer therapies. However, a key challenge faced in drug development is the efficient delivery of survivin-targeted molecules to specific areas in the body.Areas covered: This review primarily focuses on the different strategies employing nanotechnology for targeting survivin expressed in human cancers. Different nanomaterials incorporating nucleic molecules or drugs targeted at survivin are discussed and the results obtained from studies are highlighted.Expert opinion: There are extensive studies reporting different treatment regimens for cancer, however, they still result in systemic toxicity, reduced bioavailability and ineffective delivery. Novel approaches involve the use of biocompatible nanomaterials together with gene or drug molecules to target proteins such as survivin, which is overexpressed in cancerous cells. These nanoformulations allow the benefits of protecting easily degradable molecules, allow controlled release, and enhance targeted delivery and effectiveness. Hence, nanotherapy utilizing survivin targeting can be considered to play a key role in the development of personalized nanomedicine for cancer.

Preparation and characterization of novel chitosan-based microcapsule containing patchouli oil

A novel chitosan-based microcapsule containing patchouli oil was developed by a non-toxic procedure for the purpose of improving the stability of patchouli oil and achieving a durable controlled release effect. The microcapsules were characterized in case of morphology, particle size and size distribution, infrared spectrum, and the drug controlled-release properties of microcapsules were investigated under constant temperature of 25 °C. The results indicated that the microcapsules were spherical in shape with good dispersibility and smooth surface, and the particle size of microcapsules ranged from 1 to 10 ?m. The controlled-release of patchouli oil could still be remained about 60% in the microcapsules after 10 days, which demonstrated that the stability of patchouli oil were effectively improved after being encapsulated in microcapsules. It is believed that this study will not only provide a novel chitosan-based microcapsule production containing patchouli oil, but also promote the applications of microcapsule technology for improving the bioavailability of active volatile oils.

Ultrafine PDMS fibers: Preparation from in situ curing-electrospinning and mechanical characterization

Polydimethylsiloxane (PDMS) fibers with unexpected elasticity were prepared by a modified core-shell electrospinning method using a commercially-available liquid PDMS precursor (Sylgard 184) and polyvinylpyrrolidone (PVP) as core and sheath materials, respectively. The liquid PDMS precursor was crosslinked in situ to form a solid core when the newly-electrospun core-sheath nanofibers were deposited onto a hot-plate electrode collector. After dissolving the PVP sheath layer off the fibers, net PDMS fibers showed larger average diameter than core-sheath fibers, with an average diameter around 1.35 μm. The tensile properties of both single fibers and fibrous mats were measured. Single PDMS fibers had a tensile strength and elongation at break of 6.0 MPa and 212%, respectively, which were higher than those of PDMS cast film (4.9 MPa, 93%). The PDMS fiber mat had larger elongation at break than the single PDMS fibers, which can be drawn up to 403% their original length. Cyclic loading tests indicated a Mullin effect on the PDMS fiber mats. Such a superior elastic feature was attributed to the PDMS molecular orientation within fibers and the randomly-orientated fibrous structure. Highly-elastic, ultrafine PDMS fibers may find applications in strain sensors, biomedical engineering, wound healing, filtration, catalysis, and functional textiles. © The Royal Society of Chemistry 2014.

Review on fabrication and applications of ultrafine particles from animal protein fibres

Protein fibre wastes from animal hairs, feathers and insect secreted filaments can be aptly utilized by converting them into ultra-fine particles. Particles from animal protein fibres present large surface-to-weight ratio and significantly enhanced surface reactivity, that have opened up novel applications in both textile and non-textile fields. This review article summarizes the state-of-the-art routes to fabricate ultrafine particles from animal protein fibres, including direct route of mechanical milling of fibres and indirect route from fibre proteins. Ongoing research trends in novel applications of protein fibre particles in various fields, such as biomedical science, environmental protection and composite structures are presented. © 2014 The Korean Fiber Society and Springer Science+Business Media Dordrecht.

Tailored hollow mesoporous silica nanoplatforms with biological labels for colon targeted drug deliver systems

Hollow mesoporous silica nanoparticles (HMSNs) were synthesized via a new strategy. HMSNs have a high drug loading, controlled release behaviour, and specifically targeting when bioconjugated with Epidermal Growth Factor. The promising in vitro cell tests have revealed the great potential of the HMSNs to be used for cancer therapy.

Functionalized mesoporous silica nanoparticles with redox-responsive short-chain gatekeepers for agrochemical delivery.

The controlled release of salicylic acid (SA), a key phytohormone, was mediated by using a novel decanethiol gatekeeper system grafted onto mesoporous silica nanoparticles (MSNs). The decanethiol was conjugated only to the external surfaces of the MSNs through glutathione (GSH)-cleavable disulfide linkages and the introduction of a process to assemble gatekeepers only on the outer surface so that the mesopore area can be maintained for high cargo loading. Raman and nitrogen sorption isotherm analyses confirmed the successful linkage of decanethiol to the surface of MSNs. The in vitro release of SA from decanethiol gated MSNs indicated that the release rate of SA in an environment with a certain amount of GSH was significantly higher than that without GSH. More importantly, in planta experiments showed the release of SA from decanethiol gated MSNs by GSH induced sustained expression of the plant defense gene PR-1 up to 7 days after introduction, while free SA caused an early peak in PR-1 expression which steadily decreased after 3 days. This study demonstrates the redox-responsive release of a phytohormone in vitro and also indicates the potential use of MSNs in planta as a controlled agrochemical delivery system.

Drug release rate and anti-microbial effect of controlled-diffusion biopolymer membranes

In this study, a series of fibrous membranes made from cellulose acetate (CA) and polyester urethane (PEU) by co-electrospining or blend-electrospining were evaluated for drug release kinetics, in vitro anti-microbial activity and in vivo would healing performance when used as wound dressings. To stop common clinical infections, an antibacterial agent, Polyhexamethylene Biguanide (PHMB) was incorporated into e-spun fibres. The presence of CA in the wound healing membrane was found to improve hydrophilicity and permeability to air and moisture. The in vivo tests indicated that the addition of PHMB and CA considerably improved the wound healing efficiency. CA fibres became slightly swollen upon contacting with the wound exudates. It can not only speed up the liquid evaporation but also create a moisture environment for wound recovery. The drug release dynamics of membranes was controlled by the structure of membranes and component rations within membranes. The lower ration of CA:PEU retained the sound mechanical properties of membranes, and also reduced the boost release effectively and slowed down diffusion of antibacterial agent during in vitro tests. The controlled-diffusion membranes exert long-term anti-infective effect.