INTELLECTUAL MERIT: The research objective of this award is to study an innovative biomimetic nanoparticle platform that uses natural red blood cell (RBC) membranes, rather than conventional synthetic stealth biomaterials, to cloak synthetic nanoparticles for drug delivery. The approach taken will be to utilize a novel and revolutionary top-down strategy to functionalize nanoparticles by transferring the entire cellular 'utility coat' of an RBC onto the surface of drug nanocarriers. A nanoparticle thus modified is expected to exhibit similar physiologic behavior as its source cells. To achieve the primary goal, two specific research tasks will be pursued in the proposed project: (i) study the physicochemical and biological properties the RBC membrane cloaked polymeric nanoparticles, and (ii) explore effective approaches to incorporate targeting ligands on the surface of the RBC membrane cloaked nanoparticles for targeted drug delivery.
BROADER IMPACTS: If successful, this project will develop an entirely new class of biomimetic nanoparticles that combines RBC membranes with synthetic biomaterials. Such a combination of natural cellular components with synthetic biomaterials presents an innovative approach to develop novel and powerful drug delivery nanocarriers and will have profound impacts on the fields of biomaterials research and nanotechnology drug delivery. Moreover, this work highly integrates research and education. Two education thrusts will be carried out during the period of this project: (i) The PI will create new courses to shape and impact the development of the first undergraduate curriculum in 'nanoengineering' in the Untitled States. This curriculum will be provided as a model for the development of similar programs at other institutions. (ii) The PI will collaborate with the UCSD ET-CURE Program to provide minority undergraduate students with stimulating research experiences. The PI will recruit 1-2 minority undergraduate students to work on this project.
Significant efforts have been devoted to modeling drug nanocarriers after RBCs to extend nanoparticle residence time in vivo. However, an RBC-mimicking drug delivery vehicle has remained elusive to biomedical researchers. The major challenge lies in the difficulty in functionalizing nanoparticles with the complex protein makeup and surface chemistry of an RBC. The primary goal of this proposal is to study an innovative and robust biomimetic nanoparticle platform that uses natural red blood cell (RBC) membranes to cloak synthetic nanoparticles through a top-down method for drug delivery. Imagine that if a drug delivery vehicle were disguised as an RBC, it would have little risk of immunogenicity and thus low in vivo clearance, which is highly desirable for systemic drug delivery. Supported by this award, the PI has systematically studied the physicochemical and biological properties of the RBC membrane- cloaked polymeric nanoparticles (RBC-NPs), explored effective approaches to incorporating targeting ligands to the surface of the RBC-NPs for targeted drug delivery, and identified novel biomedical applications for the RBC-NPs. These results have led to 13 peer-reviewed articles. The uniqueness of the RBC membrane coating approach lies in its ability to functionalize nanoparticles with immunomodulatory proteins at an equivalent density to that on natural RBCs. Figure 1 shows that RBC membrane coating was able to functionalize sub-100 nm substrates with native CD47, yielding nanoparticles with equivalent CD47 surface density to natural RBCs. Right-side-out CD47 proteins were identified on the particle surfaces, readily exposing their extracellular domain for molecular interactions. The immune-evasive property of the RBC-NPs, as indicated by their reduced susceptibility to macrophage uptake, further verified the presence of functional immunomodulatory proteins on the particle surfaces. The non-disruptive protein functionalization through the coating of natural cellular membranes presents a robust and versatile approach in interfacing synthetic materials with biological components, offering a compelling technique for the development of bio-inspired and biomimetic nanodevices. To further functionalize the bio-inspired RBC-NPs for targeted drug delivery, a non-disruptive ligand-insertion technique has been developed to successfully achieve such functionalization goal without damaging the membrane proteins on the particle surfaces. As shown in Figure 2, targeting ligands were incorporated onto these RBC-NPs through the aid of lipid tethers and the dynamic conformation of membrane bilayers. It was demonstrated that lipid-tethered ligands could readily integrate with RBC membranes in the absence of chemical reactions. Using a small molecule folate and a nucleolin-targeting aptamer AS1411 as model ligands, targeted nanoparticles were prepared and showed receptor-specific targeting capability in vitro against cancer cells. The targeted RBC-NPs possess significant potential for cancer treatments as they integrate nature’s immune-evasive moieties with cancer-binding ligands. Besides delivering therapeutic agents to target cells and tissues, the RBC-NPs have also shown an entirely new and robust detoxification capability. Consisting of polymeric nanoparticle-supported RBC membranes, these easily fabricated RBC-NPs were able to readily take in the membrane-damaging toxins and divert them away from their cellular targets, working like a toxin-absorbing nanosponge (Figure 3). In a mouse model, the RBC-NPs markedly reduced the toxicity of staphylococcal alpha-hemolysin and thus improved the survival rate of toxin-challenged mice. The function of the RBC-NPs nanosponges as an in vivo toxin decoy can be distinguished from the current paradigm of detoxification treatments such as anti-sera, monoclonal antibodies, and small-molecule inhibitors, where toxin antagonists rely primarily on structure-specific epitopic binding. The RBC-NPs address a common membrane-disrupting mechanism shared by a broad spectrum of toxins and thus can be applied to treat a variety of toxin-induced injuries and diseases. This work was selected by the NSF Science Nation program and disseminated to the general public through a carefully created scientific video (www.nsf.gov/news/special_reports/science_nation/nanosponges.jsp). Regarding broader impacts, the research findings from this project have been integrated in a new course titled "Nanomedicine" created by the PI. This curriculum initiative has a great potential to shape and impact the development of the graduate and undergraduate curricula in "nanoengineering’. In addition, this project provided undergraduate students with stimulating research experience. A total of 7 undergraduate students have been involved in this project during the entire award period. These hands-on laboratory training is extremely helpful for undergraduates to decide their future career path. This award also significantly enhanced scientific education among K-12 students. During the award period, a total of 4 highly motivated high school students have been accepted to directly work on the project. The research program also hosted visits from high school teachers and their students to learn more about nanotechnology and nanomedicine. Moreover, the research findings from this project have been effectively disseminated to the public in large through a series of educational lectures including 27 invited talks and 12 contributed presentations at various national and international conferences and institutional seminars. The audiences included professionals, graduate students, undergraduate students, high school students and teachers, and general public. Collectively, these activities have generated tremendous broader impacts of this project.
