6 research outputs found

    Conjugated Polymers/DNA Hybrid Materials for Protein Inactivation

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    Chromophore-assisted light inactivation (CALI) is a powerful tool for analyzing protein functions due to the high degree of spatial and temporal resolution. In this work, we demonstrate a CALI approach based on conjugated polymers (CPs)/DNA hybrid material for protein inactivation. The target protein is conjugated with single-stranded DNA in advance. Single-stranded DNA can form CPs/DNA hybrid material with cationic CPs via electrostatic and hydrophobic interactions. Through the formation of CPs/DNA hybrid material, the target protein that is conjugated with DNA is brought into close proximity to CPs. Under irradiation, CPs harvest light and generate reactive oxygen species (ROS), resulting in the inactivation of the adjacent target protein. This approach can efficiently inactivate any target protein which is conjugated with DNA and has good specificity and universality, providing a new strategy for studies of protein function and adjustment of protein activity

    Highly Sensitive and Specific Multiplexed MicroRNA Quantification Using Size-Coded Ligation Chain Reaction

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    As important regulators of gene expression, microRNAs (miRNAs) are emerging as novel biomarkers with powerful predictive value in diagnosis and prognosis for several diseases, especially for cancers. There is a great demand for flexible multiplexed miRNA quantification methods that can quantify very low levels of miRNA targets with high specificity. For further analysis of miRNA signatures in biological samples, we describe here a highly sensitive and specific method to detect multiple miRNAs simultaneously in total RNA. First, we rationally design one of the DNA probes modified with two ribonucleotides, which can greatly improve the ligation efficiency of DNA probes templated by miRNAs. With the modified DNA probes, the ligation chain reaction (LCR) can be well applied to miRNA detection and as low as 0.2 fM miRNA can be accurately determined. High specificity to clearly discriminate a single nucleotide difference among miRNA sequences can also be achieved. By simply coding the DNA probes with different length of oligo (dA) for different miRNA targets, multiple miRNAs can be simultaneously detected in one LCR reaction. In our proof of principle work, we detect three miRNAs: let-7a, mir-92a, and mir-143, which can also be simultaneously detected in as small as 2 ng of total RNA sample

    Conjugated Polymers Act Synergistically with Antibiotics to Combat Bacterial Drug Resistance

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    The emergence of drug-resistant bacteria severely challenges the antimicrobial agents and antibacterial strategy. Here, we demonstrate a novel, simple, and highly efficient combination therapy strategy by direct combinations of cationic conjugated polymers (CCPs) with polypeptide antibiotics against Gram-negative and Gram-positive bacteria based on a synergistic antibacterial effect. The combination therapy method enhances the antibacterial efficacy with a significantly reduced antibiotic dosage. Also, the highly efficient and synergistic killing of drug-resistant bacteria is realized. Using combinations of CCPs and antibiotics to show increased antibacterial activity, this strategy will provide a much wider scope of the discovery of efficient antibacterial systems than that of antibiotic–antibiotic combinations. The proposed combination therapy method provides a universal and powerful platform for the treatment of pathogens, in particular, the drug-resistant bacteria, and also opens a new way for the development of efficient antibacterial systems

    Cationic Conjugated Polymers-Induced Quorum Sensing of Bacteria Cells

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    Bacteria quorum sensing (QS) has attracted significant interest for understanding cell–cell communication and regulating biological functions. In this work, we demonstrate that water-soluble cationic conjugated polymers (PFP-G2) can interact with bacteria to form aggregates through electrostatic interactions. With bacteria coated in the aggregate, PFP-G2 can induce the bacteria QS system and prolong the time duration of QS signal molecules (autoinducer-2 (AI-2)) production. The prolonged AI-2 can bind with specific protein and continuously regulate downstream gene expression. Consequently, the bacteria show a higher survival rate against antibiotics, resulting in decreased antimicrobial susceptibility. Also, AI-2 induced by PFP-G2 can stimulate 55.54 ± 12.03% more biofilm in <i>E. coli</i>. This method can be used to understand cell–cell communication and regulate biological functions, such as the production of signaling molecules, antibiotics, other microbial metabolites, and even virulence

    Visual Detection of Multiplex MicroRNAs Using Cationic Conjugated Polymer Materials

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    A simple, visual, and specific method for simultaneous detection of multiplex microRNAs (miRNAs) has been developed by integrating duplex-specific nuclease (DSN)-induced amplification with cationic conjugated polymer (CCP) materials. The probe DNA with a complementary sequence to target miRNA is labeled with fluorescein dye (FAM). Without target miRNA, the single-strand DNA probe cannot be digested by DSN. Upon adding CCPs, efficient fluorescence resonance energy transfer (FRET) from CCP to FAM occurs owing to strong electrostatic interactions between CCP and the DNA probe. In the presence of target miRNA, the DNA probe hybridizes with target miRNA followed by digestion to small nucleotide fragments by DSN; meanwhile, the miRNA is released and subsequently interacts again with the probe, resulting in the cycled digestion of the DNA probe. In this case, weak electrostatic interactions between oligonucleotide fragments and CCP lead to inefficient FRET from CCP to FAM. Thus, by triggering the FRET signal from CCP to FAM, miRNA can be specially detected, and the fluorescence color change based on FRET can be visualized directly with the naked eye under an UV lamp. Furthermore, an energy transfer cascade can be designed using CCP and DNA probes labeled at the 5′-terminus with FAM and Cy3 dyes, and the multistep FRET processes offer the ability of simultaneous detection of multiplex miRNAs

    Associated Analysis of DNA Methylation for Cancer Detection Using CCP-Based FRET Technique

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    This paper describes an associated analysis method of DNA methylation for the detection of cancer using an optically amplifying cationic conjugated polymer (CCP, poly­{(1,4-phenylene)-2,7-[9,9-bis­(6′-<i>N</i>,<i>N</i>,<i>N</i>-trimethyl ammonium)-hexyl fluorene] dibromide)}. Genomic DNA is digested by methylation-sensitive restriction endonuclease, followed by PCR amplification to incorporate fluorescein-labeled dNTP. Only methylated DNA can be amplified by PCR, and the methylation level is detected through fluorescence resonance energy transfer (FRET) between CCP and fluorescein that is incorporated into the PCR product. The methylation levels of <i>RASSF1A</i>, <i>OPCML</i>, and <i>HOXA9</i> promoters of 35 ovarian cancer samples and 11 normal samples were assayed. In accordance with the degree of methylation levels, they are clustered to three sections and assigned a value. Through an associated analysis, we acquired a threshold for cancer detection with a sensitivity of 85.7%. The assay takes about 20 h to obtain the detection results and shows great potential as a useful tool for diagnostic and screening of cancer