Publications (80) View all
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Article: Fabrication of 14 different RNA nanoparticles for specific tumor targeting without accumulation in normal organs.
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ABSTRACT: Due to structural flexibility, RNase sensitivity, and serum instability, RNA nanoparticles with concrete shapes for in vivo application remain challenging to construct. Here we report the construction of 14 RNA nanoparticles with solid shapes for targeting cancers specifically. These RNA nanoparticles were resistant to RNase degradation, stable in serum for >36 h, and stable in vivo after systemic injection. By applying RNA nanotechnology and exemplifying with these 14 RNA nanoparticles, we have established the technology and developed "toolkits" utilizing a variety of principles to construct RNA architectures with diverse shapes and angles. The structure elements of phi29 motor pRNA were utilized for fabrication of dimers, twins, trimers, triplets, tetramers, quadruplets, pentamers, hexamers, heptamers, and other higher-order oligomers, as well as branched diverse architectures via hand-in-hand, foot-to-foot, and arm-on-arm interactions. These novel RNA nanostructures harbor resourceful functionalities for numerous applications in nanotechnology and medicine. It was found that all incorporated functional modules, such as siRNA, ribozymes, aptamers, and other functionalities, folded correctly and functioned independently within the nanoparticles. The incorporation of all functionalities was achieved prior, but not subsequent, to the assembly of the RNA nanoparticles, thus ensuring the production of homogeneous therapeutic nanoparticles. More importantly, upon systemic injection, these RNA nanoparticles targeted cancer exclusively in vivo without accumulation in normal organs and tissues. These findings open a new territory for cancer targeting and treatment. The versatility and diversity in structure and function derived from one biological RNA molecule implies immense potential concealed within the RNA nanotechnology field.RNA 04/2013; · 5.09 Impact Factor -
Article: Mechanism of One-Way Traffic of Hexameric Phi29 DNA Packaging Motor with Four Electropositive Relaying Layers Facilitating Anti-Parallel Revolution.
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ABSTRACT: The importance of nanomotors in nanotechnology is akin to that of mechanical engines to daily life. The AAA+ superfamily is a class of nanomotors performing various functions. Their hexagonal arrangement facilitates bottom-up assembly for stable structures. Bacteriophage phi29 DNA-translocation motor contains three co-axial rings: a dodecamer channel, a hexameric ATPase ring, and a hexameric pRNA ring. Viral DNA-packaging motor has been believed to be a rotational machine. However, we discovered a revolution mechanism without rotation. By analogy, the earth revolves around the sun while rotating on its own axis. One-way traffic of dsDNA translocation is facilitated by five factors: 1) ATPase changes its conformation to revolve dsDNA within hexameric channel in one direction; 2) the 30° tilt of the channel subunits causes an anti-parallel arrangement between two helices of dsDNA and channel wall to advance one-way translocation; 3) unidirectional flow property of the internal channel loops serves as a ratchet valve to prevent reversal; 4) 5'-3' single-direction movement of one DNA strand along the channel wall ensures single direction; and 5) four electropositive layers interact with one strand of the electronegative dsDNA phosphate backbone, resulting in four relaying transitional pauses during translocation. The discovery of a riding system along one strand provides a motion nano-system for cargo transportation and a tool for studying force generation without coiling, friction, and torque. The revolution of dsDNA among 12 subunits offers a series of recognition sites on DNA backbone to provide additional spatial variables for nucleotides discrimination for sensing applications.ACS Nano 03/2013; · 10.77 Impact Factor -
Article: Channel Size Conversion of Phi29 DNA-Packaging Nanomotor for Discrimination of Single- and Double-Stranded Nucleic Acids.
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ABSTRACT: Nanopores have been utilized to detect the conformation and dynamics of polymers, including DNA and RNA. Biological pores are extremely reproducible at the atomic level with uniform channel sizes. The channel of the bacterial virus phi29 DNA packaging motor is a natural conduit for the transportation of double-stranded DNA (dsDNA), and has the largest diameter among the well-studied biological channels. The larger channel facilitates translocation of dsDNA, and offers more space for further channel modification and conjugation. Interestingly, the relatively large wild type channel, which translocates dsDNA, cannot detect single-stranded nucleic acids (ssDNA or ssRNA) under the current experimental conditions. Herein, we reengineered this motor channel by removing the internal loop segment of the channel. The modification resulted in two classes of channels. One class was the same size as the wild type channel, while the other class had a cross-sectional area about 60% of the wild type. This smaller channel was able to detect the real-time translocation of single stranded nucleic acids at single-molecule level. While the wild type connector exhibited a one-way traffic property with respect to dsDNA translocation, the loop deleted connector was able to translocate ssDNA and ssRNA with equal competencies from both termini. This finding of size alterations in reengineered motor channels expands the potential application of the phi29 DNA packaging motor in nanomedicine, nanobiotechnology, and high-throughput single pore DNA sequencing.ACS Nano 03/2013; · 10.77 Impact Factor -
Article: Solid-State and Biological Nanopore for Real-Time Sensing of Single Chemical and Sequencing of DNA.
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ABSTRACT: Sensitivity and specificity are two most important factors to take into account for molecule sensing, chemical detection and disease diagnosis. A perfect sensitivity is to reach the level where a single molecule can be detected. An ideal specificity is to reach the level where the substance can be detected in the presence of many contaminants. The rapidly progressing nanopore technology is approaching this threshold. A wide assortment of biomotors and cellular pores in living organisms perform diverse biological functions. The elegant design of these transportation machineries has inspired the development of single molecule detection based on modulations of the individual current blockage events. The dynamic growth of nanotechnology and nanobiotechnology has stimulated rapid advances in the study of nanopore based instrumentation over the last decade, and inspired great interest in sensing of single molecules including ions, nucleotides, enantiomers, drugs, and polymers such as PEG, RNA, DNA, and polypeptides. This sensing technology has been extended to medical diagnostics and third generation high throughput DNA sequencing. This review covers current nanopore detection platforms including both biological pores and solid state counterparts. Several biological nanopores have been studied over the years, but this review will focus on the three best characterized systems including α-hemolysin and MspA, both containing a smaller channel for the detection of single-strand DNA, as well as bacteriophage phi29 DNA packaging motor connector that contains a larger channel for the passing of double stranded DNA. The advantage and disadvantage of each system are compared; their current and potential applications in nanomedicine, biotechnology, and nanotechnology are discussed.Nano Today 02/2013; 8(1):56-74. · 15.35 Impact Factor -
Article: Incorporation of a viral DNA-packaging motor channel in lipid bilayers for real-time, single-molecule sensing of chemicals and double-stranded DNA.
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ABSTRACT: Over the past decade, nanopores have rapidly emerged as stochastic biosensors. This protocol describes the cloning, expression and purification of the channel of the bacteriophage phi29 DNA-packaging nanomotor and its subsequent incorporation into lipid membranes for single-pore sensing of double-stranded DNA (dsDNA) and chemicals. The membrane-embedded phi29 nanochannel remains functional and structurally intact under a range of conditions. When ions and macromolecules translocate through this nanochannel, reliable fingerprint changes in conductance are observed. Compared with other well-studied biological pores, the phi29 nanochannel has a larger cross-sectional area, which enables the translocation of dsDNA. Furthermore, specific amino acids can be introduced by site-directed mutagenesis within the large cavity of the channel to conjugate receptors that are able to bind specific ligands or analytes for desired applications. The lipid membrane-embedded nanochannel system has immense potential nanotechnological and biomedical applications in bioreactors, environmental sensing, drug monitoring, controlled drug delivery, early disease diagnosis and high-throughput DNA sequencing. The total time required for completing one round of this protocol is around 1 month.Nature Protocol 01/2013; 8(2):373-92. · 8.36 Impact Factor
