Supramolecular/macromolecular organic radical contrast agents (smORCAs) overcome many of the limitations of nitroxide radicals for use in magnetic resonance imaging in vivo like poor stability and weak contrast.
Virus-like particles are an emerging class of nano-biotechnology with the Tobacco Mosaic Virus (TMV) having found a wide range of applications in imaging, drug delivery, and vaccine development. TMV is typically produced in planta, and, as an RNA virus, is highly susceptible to natural mutation that may impact its properties. Over the course of 2 years, from 2018 until 2020, our laboratory followed a spontaneous point mutation in the TMV coat protein—first observed as a 30 Da difference in electrospray ionization mass spectrometry (ESI–MS). The mutation would have been difficult to notice by electrophoretic mobility in agarose or SDS-PAGE and does not alter viral morphology as assessed by transmission electron microscopy. The mutation responsible for the 30 Da difference between the wild-type (wTMV) and mutant (mTMV) coat proteins was identified by a bottom-up proteomic approach as a change from glycine to serine at position 155 based on collision-induced dissociation data. Since residue 155 is located on the outer surface of the TMV rod, it is feasible that the mutation alters TMV surface chemistry. However, enzyme-linked immunosorbent assays found no difference in binding between mTMV and wTMV. Functionalization of a nearby residue, tyrosine 139, with diazonium salt, also appears unaffected. Overall, this study highlights the necessity of standard workflows to quality-control viral stocks. We suggest that ESI–MS is a straightforward and low-cost way to identify emerging mutants in coat proteins.
Intracellular targeting is essential for the efficiently delivering of drugs and nanotherapeutics. Cytosolic transport of nanomaterials is often necessary for therapeutic delivery into cells but remains a challenge owing to...
Virus-like particles are an emerging class of nano-biotechnology with the Tobacco Mosaic Virus (TMV) having found a wide range of applications in imaging, drug delivery, and vaccine development. TMV is typically produced in planta, and, as an RNA virus, is highly susceptible to natural mutation that may impact its properties. Over the course of two years, from 2018 until 2020, our laboratory followed a spontaneous point mutation in the TMV coat protein—first observed as a 30 Da difference in electrospray ionization mass spectrometry (ESI-MS). The mutation would have been difficult to notice by electrophoretic mobility in agarose or SDS-PAGE and does not alter viral morphology as assessed by transmission electron microscopy. The mutation responsible for the 30 Da difference between the wild-type (wTMV) and mutant (mTMV) coat proteins was identified by a bottom-up proteomic approach as a change from glycine to serine at position 155 based on collision-induced dissociation data. Since residue 155 is located on the outer surface of the TMV rod, it is feasible that the mutation alters TMV surface chemistry. However, enzyme-linked immunosorbent assays found no difference in binding between mutant and wild-type TMV. Functionalization of a nearby residue, tyrosine 139, with diazonium salt, also appears unaffected. Overall, this study highlights the necessity of standard workflows to quality-control viral stocks. We suggest that ESI-MS is a straightforward and low-cost way to identify emerging mutants in coat proteins.
Nanoparticle-based therapeutics have been applied in a broad range of clinical and pre-clinical applications from diagnosis to treatment for cancer. A wide range of synthetic and naturally occurring materials such as polymers, metal oxides, silicate, liposomes, and carbon nanotubes have been developed to overcome key barriers in small molecule therapeutics including intracellular trafficking, cell/tissue targeting, poor biodistribution, and low efficiency. Virus like particles (VLPs)—engineered and non-infectious self-assembling systems based on viral nanostructures—are new approach toward overcoming these limitations, as they are a protein-based nanomaterial that closely mimics the highly symmetrical and polyvalent conformation of viruses while lacking the viral genomes. Their innate biocompatibility, biodegradability, monodispersity, mild immunogenicity, and safety combined with the capacity to chemically modify the interior and exterior surfaces of these systems offer scientists a highly customizable tool to design and engineer multi-component therapeutic agents. In this review, we discuss how these systems have been used in a wide array of cancer treatments including phototherapy, immunotherapy, gene therapy, and chemotherapy.
Intracellular targeting is an important aspect of the efficient delivery of drugs and nanotherapeutics. Cytosolic transport of nanomaterials is often an essential requirement for therapeutic delivery into cells but remains a challenge owing to the endosomal trap and eventual lysosomal degradation of cargo. To address this, we designed a functional carrier that escapes the endosome and delivers biological materials into the cell's cytoplasm. For this purpose, we synthesized a glutathione-sensitive linker that connects the well-known mitochondria targeting lipophilic triphenylphosphonium cation (TPP) to the surface of a proteinaceous nanoparticle based on the engineered virus-like particle (VLP) Qβ. Once in the cytosol, the thiol sensitive linker severs the TPP from the nanoparticle, halting its trafficking to the mitochondria, and marooning it in the cytosol. We demonstrate the successful in vitro cytosolic delivery of a VLP loaded with Green Fluorescent Protein, where evenly distributed fluorescence is observed in A549 lung cancer cells after four hours. We further demonstrate successful cytosolic delivery by showing that encapsulating siRNA inside the VLP promotes luminescence silencing in luciferase expressing HeLa cells more efficiently than VLPs that lack our sheddable TPP linker.
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