Interaction of Nanomaterials with Biological systems.pptx

Interaction of Nanomaterials with Biological systems.pptx

1. Interaction of Nanomaterials with Biological Systems Dr. Sadaf Hameed

2. Contents 1. Introduction 2. Interaction of Nanomaterials with Biological Systems 2.1. Protein Binding 2.2. Ligand-Mediated Interactions 2.3.Interactions during Intracellular Processing

3. Introduction In recent years, the use of nanomaterials for targeted delivering and controlled releasing drugs, crossing biological barriers, activating immune cells, and reacting with redox species for diseases treatment has been widely investigated. However, insufficient understanding of the interactions of nanomaterials with biological molecules and structures (such as, proteins, membranes, phospholipids, DNA, and free radicals) hinders the application of nanomedicine. Upon entering into biological fluids, engineered nanomaterials can rapidly interact with various biomolecules.

4. Introduction T here are three types of interaction between nanomaterials and molecules in living systems, including: P rotein binding Ligand-mediated interactions, I nteractions during intracellular processing

5. Protein Binding The interaction between protein and nanomaterials is the basis of nanoparticle bio-reactivity. Surface charge, properties, and structure of proteins could be changed by interaction with nanomaterials. The common formation between nanomaterials and protein complexes is referred to the nanoparticle-protein corona. “Hard corona” is the irreversible binding of proteins while “soft corona” is the quickly reversible binding of proteins.

6. Protein Binding Protein could interact with nanomaterials via hydrogen bonds, solvation forces, and Van der Waals interactions. Proteins such as albumin, immunoglobulins, fibrinogen, and apolipoproteins are strongly attached to polymeric NPs, liposomes, iron oxide NPs and carbon nanotubes. The interaction of protein and NPs depends on several factors such as the kinds of protein, composition, amount of protein available to interact with NPs surface and the affinity of the protein toward the NPs surface . Also, the structures of proteins could be changed by interaction with NPs. This change depends on which types of NPs that proteins interact with. For examples, gold NPs change the structures of bovine serum albumin (BSA) while this phenomenon did not occur when BSA interact with carbon C60 fullerene.

7. Protein Binding Disadvantages : This interaction may thus lead to the loss of performance of NPs due to an increase in hydrodynamic size and aggregation . The non-specific protein interaction could be led to false positive signals and low signal-to-noise ratios , thus reducing the potential of nanotechnology-based diagnostic and arrays. As a result, the non-specific protein interaction with NPs should be decreased. For example , poly(ethylene glycol) (PEG) has been used for surface functionalization of nanomaterials in order to reduce the protein absorption through hydrophilicity and steric repulsion effects, thus making residence time of NPs in blood long enough to reach their target . Doxil ® and Genexol -PM® are two commercial products that used PEG for surface functionalization. Doxil ® is PEGylated liposomal doxorubicin while Genexol -PM® is PLA-PEG micelle form of paclitaxel. The encapsulation of doxorubicin inside PEGygated NPs could extend the circulation half-life of drug in blood and result in higher uptake of doxorubicin in target cells.

8. Chemical structure of a Doxil liposome. Schematic diagram showing the proposed mechanism of Doxil transport to the tumor cells. Step 1: circulation of the doxorubicin-containing liposomes in the blood circulation with a half-life of approximately 55 hours (for humans) after injection without releasing the drug. Step 2: extravasation of 85 nm liposomal nano-vehicles into the tissue compartment through the leaky tumor vasculature. Step 3: release of the free doxorubicin from the liposome, believed to be due to the physical and chemical breakdown of the liposomal membrane in the intestinal fluid because of the low pH, the presence of oxidizing agents and enzymes, or via the uptake by macrophages. Step 4: penetration of the free drug into the tumor cells, binding with the nucleic acid, followed by killing of the tumor cells.

9. Protein Binding Advantages of Protein Bindings: B esides disadvantages, protein-binding also have some advantages. The decoration of nanomaterials with suitable proteins could be useful for targeting therapeutic sites in some cases . For example, albumin-coated paclitaxel (nab-PTX, Abraxane) has a higher response rate in a subset of patients. SPARC (secreted protein acidic and rich in cysteine) is a glycosylated 43 kDa which has a high affinity to albumin. SPARC modulates the cell and extracellular matrix interactions and acts as a cell regulator such as proliferation, survival, and cell migration. It is known to be upregulated expression in cancer cells, overexpression of SPARC is associated with increased tumor invasion and metastasis.

10. Nano-Medicine: Abraxane Paclitaxel: Used for the treatment of  ovarian cancer, breast cancer, lung cancer, Kaposi sarcoma, cervical cancer, and pancreatic cancer. It is given by injection into a vein . Abraxane ®  is the first approved na notechnology- b ased chemotherapeutic (nab-paclitaxel). Abraxane is used to treat advanced  cancer of the breast ,  lung , or  pancreas . Abraxane is a formulation of Paclitaxel and the natural nanoparticle Albumin. Challenge: it is hydrophobic, e.g. it has poor solubility in aqueous based media (e.g. blood plasma), and therefore it efficacy is poor . Solution: Attach it to a hydrophophilic material. 7 nm Albumin 2 nm Paclitaxel Albumin : A naturally occurring protein nanoparticle found in blood plasma. It accumulates in cancer cells . Albumin can make Paclitaxel soluble in blood plasma and take it into cancer cells .

11. Researchers investigated the efficiencies of nab-PTX in 60 patients and found that the responses in SPARC-positive patients were higher than SPARC-negative patients (83% compared to 25%). The interaction of albumin and SPARC could tailor the accumulation of nab-PTX in the tumor. In addition, paclitaxel has been shown to be transported across endothelial barriers via the Gp60 receptor and caveolin-1 mediated transcytosis. The nab-technology platform as a means of connecting two endogenous albumin pathways in order to target and improve drug delivery. Step 1: injection of nab-paclitaxel into blood vessels; Step 2: suspended in the blood, nabpaclitaxel dissociates into individual particles; Step 3: because it is associated with albumin, nab-paclitaxel binds to Gp60 receptors present on the endothelial cells of tumour blood vessels; Step 4: binding of albumin to gp60 activates caveolin-1 which creates vesicles (caveolae) in the endothelial cell wall; these caveolae fill with nab-paclitaxel and migrate across the cytoplasm. Steps 5&6: caveolae deposit their contents into the interstitium of the tumour , where nab-paclitaxel binds to SPARC; Step 7: accumulation of nab-paclitaxel via SPARC at tumour cell membranes; Step 8: diffusion of paclitaxel into the intracellular compartment and subsequent induction of cell death.

12. Ligand-Mediated Interactions Nanomaterials could interact with target via surface ligand. The ligands which were frequently used are antibodies fragments, proteins, peptides, small molecules, and aptamers (As shown in Figure). There are two types of targets: ubiquitous targets (existed in all tissues) and cell-specific targets (existed only in diseased tissues). An example of the ubiquitous target is transferrin ( Tf ). This 80 kDa blood-circulating glycoprotein exists in all tissue but overexpressed in tumor cells. Investigator used Tf -modified cyclodextrin to bind to transferrin receptors ( TfR ) and trigger cellular uptake via clathrin -coated pits.

13. Figure: (a) Tf -modified cyclodextrin, (b) transfer of NPs into patients, (c) the NPs could circulate in the patient blood and then escape through the tumor “leaking” blood vessels, (d) NPs thus enter into the cells via receptor-mediated endocytosis mechanisms, (e) Tf -modified cyclodextrin have various interactions on cell surface thus stimulate entrance into the cancer cell

14. Ligand-Mediated Interactions An example of cell-specific targets was prostate-specific membrane antigen (PSMA). Farokhzad et al. (2006) showed that the PSMA-binding aptamers exist on the surface of prostate-specific NPs enhanced the uptaking by cancer cells.

15. Ligand-Mediated Interactions The chosen ligands in nanomaterials design effects the efficiency of ex vivo diagnosis systems. The false positive and negative could be reduced with the high affinity and specificity of ligands. The ligand arrangement on the NPs surface could affect the cellular uptake. Researcher found that organically amphiphilic gold NPs with different ligand arrangement have different in cell penetration ability. While NPs with an ordered ribbon-like alternating arrangement could penetrate the cells more efficiently than NPs of a random arrangement of ligand on their surface

16. Interactions during Intracellular Processing When up-taking by cells, some drug-containing NPs avoid the degradation by lysosome while others used this environment for the enzymatic release of drugs to therapeutic targets. The endocytosis process can transport NPs inside the cytoplasm via phagocytosis and pinocytosis ( clathrin -dependent, caveolin-dependent, receptor-mediated, and caveolin-independent endocytosis). In phagocytosis , cells uptakes only solid materials (cell eating) while in pinocytosis , cell can uptake an amount of liquid from the extracellular environment (cell drinking). Understanding the way of nanomaterial’s interaction during intracellular process helps to define exact strategies for delivery of drugs to individual sub-cellular compartments.

17. Interactions during Intracellular Processing Endocytosis pathways to transfer NPs into cells

18. Interactions during Intracellular Processing

19. Interactions during Intracellular Processing The cellular internalization pathways depend on size of nanomaterials : nanomaterials with diameters less than 100 nm can enter the cells while nanomaterials with diameters less than 40 nm could enter the cell nucleus while with diameters below 35 nm could pass the blood-brain barrier (BBB). The cellular internalization is also depending on shapes of nanomaterials . For examples, nanorods were less efficient internalization than nanospheres because cells take a longer time to wrap a rod than a sphere. The internalization of nanomaterials could be affected by protein adsorption, physical characteristics, and the properties of interacting cells. For examples, when investigating the charge effect on the uptake of mesoporous silica NPs (MSN) by HeLa cells, Slowing et al. showed that the effective dose at 50% of internalization (ED50) increased with the increase in the negative value of surface charge of MSN . More importantly , MSN with different surface charge will be internalized by different endocytic pathway . For example , while non-functionalized MSN materials were endocytosed through the clathrin -mediated process, functionalized MSN materials were endocytosed through the caveolin-mediated pathway.

20. Reference Chapter 4 : Interaction of Nanomaterials with Biological Systems; from Introduction to Bionanotechnology.