Monthly Archives: August 2017

PolySciTech mPEG-PLGA/PLGA-rhodamine used in the development of nanoparticle-based intracellular MRSA treatment

MRSA is a bacterial infection that is highly resistant to conventional antibiotic treatments or other therapies. It is still affected by vancomycin, but the bacterial spores have the capability to ‘hide’ inside of cells making it very difficult to treat. One means around this is to use nanoparticles for delivery of the antibiotic to the cells to ensure suitable vancomycin in a local concentration to kill off the bacteria. Recently, researchers at Purdue University used mPEG-PLGA (Polyvivo AK030) and rhodamine-B labelled PLGA (PolyVivo AV011) from PolySciTech (www.polyscitech.com) to create pH sensitive nanoparticles designed for intracellular delivery of vancomycin. This research holds promise to improve treatments of this deadly bacterial infection. Read more: Pei, Yihua, Mohamed F. Mohamed, Mohamed N. Seleem, and Yoon Yeo. “Particle engineering for intracellular delivery of vancomycin to methicillin-resistant Staphylococcus aureus (MRSA)-infected macrophages.” Journal of Controlled Release (2017). http://www.sciencedirect.com/science/article/pii/S0168365917307745

“Abstract: Methicillin-resistant Staphylococcus aureus (MRSA) infection is a serious threat to the public health. MRSA is particularly difficult to treat when it invades host cells and survive inside the cells. Although vancomycin is active against MRSA, it does not effectively kill intracellular MRSA due to the molecular size and polarity that limit its cellular uptake. To overcome poor intracellular delivery of vancomycin, we developed a particle formulation (PpZEV) based on a blend of polymers with distinct functions: (i) poly(lactic-co-glycolic acid) (PLGA, P) serving as the main delivery platform, (ii) polyethylene glycol-PLGA conjugate (PEG-PLGA, p) to help maintain an appropriate level of polarity for timely release of vancomycin, (iii) Eudragit E100 (a copolymer based on dimethylaminoethyl methacrylate, butyl methacrylate and methyl methacrylate, E) to enhance vancomycin encapsulation, and (iv) a chitosan derivative called ZWC (Z) to trigger pH-sensitive drug release. PpZEV NPs were preferentially taken up by the macrophages due to its size (500–1000 nm) and facilitated vancomycin delivery to the intracellular pathogens. Accordingly, PpZEV NPs showed better antimicrobial activity than free vancomycin against intracellular MRSA and other intracellular pathogens. When administered intravenously, PpZEV NPs rapidly accumulated in the liver and spleen, the target organs of intracellular infection. Therefore, PpZEV NPs is a promising carrier of vancomycin for the treatment of intracellular MRSA infection. Keywords: Nanoparticles, Intracellular drug delivery, pH-sensitive, Macrophages, Intracellular MRSA, Vancomycin”

Improved targeted-delivery system using oriented antibody fragments developed using PLGA-PEG-Azide from PolySciTech.

A powerful tool for medicinal delivery is the use of a nanoparticle with a surface covered in a specific antibody or targeting ligand. Because these antibodies and ligands bind specifically to certain protein factors these can be tailored to target to specific cells, notably cancer cells. Since antibody bonding is a stereochemical process, shape and orientation of the antibody matters in terms of its capability to bind. If the active site of the ligand is facing inwards, towards the nanoparticle, it may not work well at all. Recently, researchers working at Queen’s University Belfast, University College London, (UK) and Universidade de Lisboa (Portugal) used PLGA-PEG-Azide from PolySciTech (www.polyscitech.com, PolyVivo AI085) to generate nanoparticles which had very precisely controlled antibody orientation on their surface allowing for improved functionality and targeting. They tested this system for its ability to bind to HER2 (a factor that is overexpressed in cancer cells) and found it had substantially higher binding than a randomly oriented nanoparticle system. This research holds promise for developing a wide-array of targeted delivery systems for treating a variety of diseases, most notably cancer. Read more: M. Greene, D. A. Richards, J. Nogueira, K. Campbell, P. Smyth, M. Fernandez, C. J. Scott and V. Chudasama “Generating Next-Generation Antibody-Nanoparticle Conjugates through the Oriented Installation of Non-Engineered Antibody Fragments” Chem. Sci., 2017, DOI: 10.1039/C7SC02747H. (http://pubs.rsc.org/en/Content/ArticleLanding/2017/SC/C7SC02747H#!divAbstract)

“Abstract: The successful development of targeted nanotherapeutics is contingent upon the conjugation of therapeutic nanoparticles to target-specific ligands, with particular emphasis being placed on antibody-based ligands. Thus, new methods that enable the covalent and precise installation of targeting antibodies to nanoparticle surfaces are greatly desired, especially those which do not rely on costly and time-consuming antibody engineering techniques. Herein we present a novel method for the highly controlled and oriented covalent conjugation of non-engineered antibody F(ab) fragments to PLGA-PEG nanoparticles using disulfide-selective pyridazinedione linkers and strain-promoted alkyneazide click chemistry. Exemplification of this method with trastuzumab and cetuximab showed significant improvements in both conjugation efficiency and antigen binding capability, when compared to commonly employed strategies for antibody-nanoparticle construction. This new approach paves the way for the development of antibody-targeted nanomedicines with improved paratope availability, reproducibility and uniformity to enhance both biological activity and ease of manufacture.”

PolySciTech PLGA-NH2 used in research thesis on nanoparticle-surface interactions with living cells

Nanoparticles have been around for many years but we are still, as a species, just scratching at the surface of understanding them. Of course, the surface is the most important part of a nanoparticle since, due to their incredibly small size, they have an incredible surface area to volume ratio. For example, 1g of PLGA nanoparticles (100 nm) would have a surface area of 7.8 square meters (a little larger than a typical parking space for a car). For this reason, the surface and how it interacts with living organisms is the most important aspect of nanoparticle technology. Recently, Angie (Morris) Thorn at University of Iowa published a PhD thesis which details efforts to broaden our understanding of nanoparticle surface interactions with cells. This includes work with PLGA-NH2 (PolyVivo AI063) from PolySciTech (www.polyscitech.com) to generate nanoparticles covered with either chitosan (for mucoadhesion) or TPP (mitochondria-targeting) to create targeted nanoparticles as drug-delivery vectors. Read more: Thorn, Angie Sue Morris. “The impact of nanoparticle surface chemistry on biological systems.” (2017). http://ir.uiowa.edu/etd/5659/

“Abstract: The unique properties of nanomaterials, such as their small size and large surface area-to-volume ratios, have attracted tremendous interest in the scientific community over the last few decades. Thus, the synthesis and characterization of many different types of nanoparticles has been well defined and reported on in the literature. Current research efforts have redirected from the basic study of nanomaterial synthesis and their properties to more application-based studies where the development of functionally active materials is necessary. Today such nanoparticle-based systems exist for a range of biomedical applications including imaging, drug delivery and sensors. The inherent properties of the nanomaterial, although important, aren’t always ideal for specific applications. In order to optimize nanoparticles for biomedical applications it is often desirable to tune their surface properties. Researchers have shown that these surface properties (such as charge, hydrophobicity, or reactivity) play a direct role in the interactions between nanoparticles and biological systems can be altered by attaching molecules to the surface of nanoparticles. In this work, the effects of physicochemical properties of a wide variety of nanoparticles was investigated using in vitro and in vivo models. For example, copper oxide (CuO) nanoparticles were of interest due to their instability in biological media. These nanoparticles undergo dissolution when in an aqueous environment and tend to aggregate. Therefore, the cytotoxicity of two sizes of CuO NPs was evaluated in cultured cells to develop a better understanding of how these propertied effect toxicity outcomes in biological systems. From these studies, it was determined that CuO NPs are cytotoxic to lung cells in a size-dependent manner and that dissolved copper ions contribute to the cytotoxicity however it is not solely responsible for cell death. Moreover, silica nanoparticles are one of the most commonly used nanomaterials because they are easy to synthesize and their properties (such as size, porosity and surface chemistry) can be fine-tuned. Silica nanoparticles can be found in thousands of commercially available products such as toothpastes, cosmetics and detergents and are currently being developed for biomedical applications such as drug delivery and biomedical imaging. Our findings herein indicate that the surface chemistry of silica nanoparticles can have an effect on lung inflammation after exposure. Specifically, amine-modified silica NPs are considered to be less toxic compared to bare silica nanoparticles. Together, these studies provide insight into the role that material properties have on toxicity and allow for a better understanding of their impact on human and environmental health. The final aim of this thesis was to develop surface-modified nanoparticles for drug delivery applications. For this, biodegradable, polymeric NPs were used due to their inert nature and biocompatibility. Furthermore, polymeric NPs are excellent for loading drugs and using them as drug delivery vehicles. In this work, poly (lactic-co-glycolic acid) (PLGA) NPs were loaded with a therapeutic peptide. These NPs were then coated with chitosan (a mucoadhesive polymer) for the treatment of allergic asthma or coated with a small cationic mitochondrial targeting agent for the treatment of ischemia/reperfusion injury. Taken as a whole, this thesis sheds light on the impact of NPs on human health. First by providing useful toxological data for CuO and silica NPs as well as highlighting the potential of surface-modified polymeric NPs to be used in drug delivery-based applications. Keywords: Cell Culture, Nanoparticle, Toxicity”