Dennis Diaz

Bio: Dennis Diaz is an academic researcher from Macquarie University. The author has contributed to research in topics: Nanocages & Biology. The author has an hindex of 2, co-authored 4 publications receiving 54 citations.

Bioengineering Strategies for Protein-Based Nanoparticles.

Abstract: In recent years, the practical application of protein-based nanoparticles (PNPs) has expanded rapidly into areas like drug delivery, vaccine development, and biocatalysis. PNPs possess unique features that make them attractive as potential platforms for a variety of nanobiotechnological applications. They self-assemble from multiple protein subunits into hollow monodisperse structures; they are highly stable, biocompatible, and biodegradable; and their external components and encapsulation properties can be readily manipulated by chemical or genetic strategies. Moreover, their complex and perfect symmetry have motivated researchers to mimic their properties in order to create de novo protein assemblies. This review focuses on recent advances in the bioengineering and bioconjugation of PNPs and the implementation of synthetic biology concepts to exploit and enhance PNP's intrinsic properties and to impart them with novel functionalities.

Bioengineering a Light-Responsive Encapsulin Nanoreactor: A Potential Tool for In Vitro Photodynamic Therapy.

Abstract: Encapsulins, a prokaryotic class of self-assembling protein nanocompartments, are being re-engineered to serve as "nanoreactors" for the augmentation or creation of key biochemical reactions. However, approaches that allow encapsulin nanoreactors to be functionally activated with spatial and temporal precision are lacking. We report the construction of a light-responsive encapsulin nanoreactor for "on demand" production of reactive oxygen species (ROS). Herein, encapsulins were loaded with the fluorescent flavoprotein mini-singlet oxygen generator (miniSOG), a biological photosensitizer that is activated by blue light to generate ROS, primarily singlet oxygen (1O2). We established that the nanocompartments stably encased miniSOG and in response to blue light were able to mediate the photoconversion of molecular oxygen into ROS. Using an in vitro model of lung cancer, we showed that ROS generated by the nanoreactor triggered photosensitized oxidation reactions which exerted a toxic effect on tumor cells, suggesting utility in photodynamic therapy. This encapsulin nanoreactor thus represents a platform for the light-controlled initiation and/or modulation of ROS-driven processes in biomedicine and biotechnology.

Exploring the Self-Assembly of Encapsulin Protein Nanocages from Different Structural Classes

Abstract: Encapsulins, self-assembling icosahedral protein nanocages derived from prokaryotes, represent a versatile set of tools for nanobiotechnology. However, a comprehensive understanding of the mechanisms underlying encapsulin self-assembly, disassembly, and reassembly is lacking. Here, we characterise the disassembly/reassembly properties of three encapsulin nanocages that possess different structural architectures: T = 1 (24 nm), T = 3 (32 nm), and T = 4 (42 nm). Using spectroscopic techniques and electron microscopy, encapsulin architectures were found to exhibit varying sensitivities to the denaturant guanidine hydrochloride (GuHCl), extreme pH, and elevated temperature. While all encapsulins showed the capacity to reassemble following GuHCl-induced disassembly (within 75 min), only the smallest T = 1 nanocage reassembled after disassembly in basic pH (within 15 min). Furthermore, atomic force microscopy revealed that all encapsulins showed a significant loss of structural integrity after undergoing sequential disassembly/reassembly steps. These findings provide insights into encapsulins disassembly/reassembly dynamics, thus informing their future design, modification, and application.

Bioengineering a light-responsive encapsulin nanoreactor: a potential tool for photodynamic therapy

Abstract: Encapsulins, a prokaryotic class of self-assembling protein nanocompartments, are being re-engineered to serve as nanoreactors for the augmentation or creation of key biochemical reactions. However, approaches that allow encapsulin nanoreactors to be functionally activated with spatial and temporal precision is lacking. We report the construction of a light-responsive encapsulin nanoreactor for on-demand production of reactive oxygen species (ROS). Herein, encapsulins were loaded with the fluorescent flavoprotein mini-Singlet Oxygen Generator (miniSOG), a biological photosensitizer that is activated by blue-light to generate ROS, primarily singlet oxygen. We established that the nanocompartments stably encased miniSOG, and in response to blue-light were able to mediate the photoconversion of molecular oxygen into ROS. Using an in vitro model of lung cancer, ROS generated by the nanoreactor was shown to trigger photosensitized oxidation reactions that exerted a toxic effect on tumour cells, suggesting utility in photodynamic therapy. This encapsulin nanoreactor thus represents a platform for the light-controlled initiation and/or modulation of ROS-driven processes in biomedicine and biotechnology.

In vivo fate of systemically administered encapsulin protein nanocages and implications for their use in targeted drug delivery

Abstract: Encapsulins, self-assembling protein nanocages derived from prokaryotes, are promising nanoparticle-based drug delivery systems (NDDS). However, the in vivo behavior and fate of encapsulins are poorly understood. In this pre-clinical study, we probe the interactions between the model encapsulin from Thermotoga maritima (TmEnc) and key biological barriers encountered by NDDS. Here, a purified TmEnc formulation that exhibited colloidal stability, storability, and blood compatibility was intravenously injected into BALB/c mice. TmEnc had an excellent nanosafety profile, with no abnormal weight loss or gross pathology observed, and only temporary alterations in toxicity biomarkers detected. Notably, TmEnc demonstrated immunogenic properties, inducing the generation of nanocage-specific IgM and IgG antibodies, but without any prolonged pro-inflammatory effects. An absence of antibody cross-reactivity also suggested immune-orthogonality among encapsulins systems. Moreover, TmEnc formed a serum-derived protein corona on its surface which changed dynamically and appeared to play a role in immune recognition. TmEnc’s biodistribution profile further revealed its sequestration from the blood circulation by the liver and then biodegraded within Kupffer cells, thus indicating clearance via the mononuclear phagocyte system. Collectively, these findings provide critical insights into how encapsulins behave in vivo, thereby informing their future design, modification, and application in targeted drug delivery.

Biomimetic peptide self-assembly for functional materials

Abstract: Natural biomolecular systems have evolved to form a rich variety of supramolecular materials and machinery fundamental to cellular function. The assembly of these structures commonly involves interactions between specific molecular building blocks, a strategy that can also be replicated in an artificial setting to prepare functional materials. The self-assembly of synthetic biomimetic peptides thus allows the exploration of chemical and sequence space beyond that used routinely by biology. In this Review, we discuss recent conceptual and experimental advances in self-assembling artificial peptidic materials. In particular, we explore how naturally occurring structures and phenomena have inspired the development of functional biomimetic materials that we can harness for potential interactions with biological systems. As our fundamental understanding of peptide self-assembly evolves, increasingly sophisticated materials and applications emerge and lead to the development of a new set of building blocks and assembly principles relevant to materials science, molecular biology, nanotechnology and precision medicine. The self-assembly of biomimetic peptides can mimic complex natural systems involving whole proteins. This Review describes how synthetic peptides afford tunable scaffolds for biomineralization, drug delivery and tissue growth.

Optimizing use of theranostic nanoparticles as a life-saving strategy for treating COVID-19 patients.

Abstract: On the 30th of January 2020, the World Health Organization fired up the sirens against a fast spreading infectious disease caused by a newly discovered Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and gave this disease the name COVID-19. While there is currently no specific treatment for COVID-19, several off label drugs approved for other indications are being investigated in clinical trials across the globe. In the last decade, theranostic nanoparticles were reported as promising tool for efficiently and selectively deliver therapeutic moieties (i.e. drugs, vaccines, siRNA, peptide) to target sites of infection. In addition, they allow monitoring infectious sides and treatment responses using noninvasive imaging modalities. While intranasal delivery was proposed as the preferred administration route for therapeutic agents against viral pulmonary diseases, NP-based delivery systems offer numerous benefits to overcome challenges associated with mucosal administration, and ensure that these agents achieve a concentration that is many times higher than expected in the targeted sites of infection while limiting side effects on normal cells. In this article, we have shed light on the promising role of nanoparticles as effective carriers for therapeutics or immune modulators to help in fighting against COVID-19.

Protein-based antigen presentation platforms for nanoparticle vaccines

Abstract: Modern vaccine design has sought a minimalization approach, moving to the isolation of antigens from pathogens that invoke a strong neutralizing immune response. This approach has created safer vaccines but may limit vaccine efficacy due to poor immunogenicity. To combat global diseases such as COVID-19, malaria, and AIDS there is a clear urgency for more effective next-generation vaccines. One approach to improve the immunogenicity of vaccines is the use of nanoparticle platforms that present a repetitive array of antigen on its surface. This technology has been shown to improve antigen presenting cell uptake, lymph node trafficking, and B-cell activation through increased avidity and particle size. With a focus on design, we summarize natural platforms, methods of antigen attachment, and advancements in generating self-assembly that have led to new engineered platforms. We further examine critical parameters that will direct the usage and development of more effective platforms.

Three-Dimensional Protein Cage Array Capable of Active Enzyme Capture and Artificial Chaperone Activity

Abstract: Development of protein cages for encapsulation of active enzyme cargoes and their subsequent arrangement into a controllable three-dimensional array is highly desirable. However, cargo capture is t...

Recent Advancements of Nanomedicine towards Antiangiogenic Therapy in Cancer.

Abstract: Angiogenesis is a process of generation of de-novo blood vessels from already existing vasculature. It has a crucial role in different physiological process including wound healing, embryonic development, and tumor growth. The methods by which therapeutic drugs inhibit tumor angiogenesis are termed as anti-angiogenesis cancer therapy. Developments of angiogenic inhibiting drugs have various limitations causing a barrier for successful treatment of cancer, where angiogenesis plays an important role. In this context, investigators developed novel strategies using nanotechnological approaches that have demonstrated inherent antiangiogenic properties or used for the delivery of antiangiogenic agents in a targeted manner. In this present article, we decisively highlight the recent developments of various nanoparticles (NPs) including liposomes, lipid NPs, protein NPs, polymer NPs, inorganic NPs, viral and bio-inspired NPs for potential application in antiangiogenic cancer therapy. Additionally, the clinical perspectives, challenges of nanomedicine, and future perspectives are briefly analyzed.