A facile and scalable strategy for constructing Janus cotton fabric with persistent antibacterial activity

Natural cotton fibers have attached considerable attention due to their excellent wearing comfort, breathability and warmth. However, it remains a challenge to devise a scalable and facile strategy to retrofit natural cotton fibers. Here, the cotton fiber surface was oxidized by sodium periodate with a mist process, then [2-(methacryloyloxy) ethyl] trimethylammonium chloride (DMC) was co-polymerized with hydroxyethyl acrylate (HA) to obtain an antibacterial cationic polymer (DMC-co-HA). The self-synthesized polymer was covalently grafted onto the aldehyde-functionalized cotton fibers via an acetal reaction between hydroxyl groups of the polymer and aldehyde groups of the oxidized cotton surface. Finally, the resulted Janus functionalized cotton fabric (JanCF) revealed robust and persistent antimicrobial activity. The antibacterial test showed that when the molar ratio of DMC/HA was 50: 1, JanCF possessed the best BR (bacterial reduction) values of 100 % against Escherichia coli and Staphylococcus aureus. Furthermore, the BR values could be maintained over 95 % even after the durability test. In addition, JanCF exhibited excellent antifungal activity against Candida albicans. The cytotoxicity assessment confirmed that JanCF exhibited a reliable safety effect on human skin. Particularly, the intrinsic outstanding characteristics (strength, flexibility, etc.) of the cotton fabric were not considerably deteriorated compared to the control samples.

Label-free detection of HPV mRNA with an artificial chaperone-enhanced MNAzyme (ACEzyme)-based electrochemical sensor

Nucleic acid biosensors for point-of-care (POC) diagnostic applications are highly desirable. The ability to detect DNA and RNA in a simple, rapid, affordable and portable format leads to a range of important applications for early screening in the field of disease monitoring and management. Herein, we report the development of an isothermal, label-free electrochemical biosensor that was designed on the basis of target-driven MNAzyme cleavage activity. Hybridization with HPV mRNA, a model nucleic acid target, activated MNAzyme and initiated the cleavage of immobilized hairpin substrates, leading to changes in the electrochemical signal. Under optimal conditions, a detection limit of 2.6 pM was obtained with an incubation time of 60 min. Furthermore, an artificial chaperone-enhanced MNAzyme (ACEzyme) system was integrated to an electrochemical biosensor for the first time. The analytical performance of the biosensor was enhanced, and the detection time was significantly reduced by the addition of PLL-g-Dex, which exhibits nucleic acid chaperone-like activity. A detection limit of 0.88 pM was obtained with a threefold decrease in incubation time without prior amplification. The proposed biosensing platform shows the advantages of simple fabrication and operation, good selectivity in the presence of single-base mismatch, and excellent versatility in a complex mixture of total RNA. We believe that this isothermal, label-free, and protein-free nucleic acid analysis platform could provide foundations for the further development of a universal nucleic acid biosensing platform for clinical application.

One-step isothermal RNA detection with LNA-modified MNAzymes chaperoned by cationic copolymer

RNA detection permits early diagnosis of several infectious diseases and cancers, which prevent propagation of diseases and improve treatment efficacy. However, standard technique for RNA detection such as reverse transcription-quantitative polymerase chain reaction has complicated procedure and requires well-trained personnel and specialized lab equipment. These shortcomings limit the application for point-of-care analysis which is critical for rapid and effective disease management. The multicomponent nucleic acid enzymes (MNAzymes) are one of the promising biosensors for simple, isothermal and enzyme-free RNA detection. Herein, we demonstrate simple yet effective strategies that significantly enhance analytical performance of MNAzymes. The addition of the cationic copolymer and structural modification of MNAzyme significantly enhanced selectivity and activity of MNAzymes by 250 fold and 2,700 fold, respectively. The highly simplified RNA detection system achieved a detection limit of 73 fM target concentration without additional amplification. The robustness of MNAzyme in the presence of non-target RNA was also improved. Our finding opens up a route toward the development of an alternative rapid, sensitive, isothermal, and protein-free RNA diagnostic tool, which expected to be of great clinical significance.

Cationic copolymer-chaperoned short-armed 10-23 DNAzymes

The cationic copolymer poly(L-lysine)-graft-dextran (PLL-g-Dex) has nucleic acid chaperone-like activity. The copolymer facilitates both DNA hybridization and strand exchange reactions. For these reasons, DNA-based enzyme (DNAzyme) activity is enhanced in the presence of copolymer. In this study, we evaluated activities of DNAzymes with substrate-binding arms (S-arms) of various lengths. The copolymer promoted DNAzyme reactivity and turnover efficacy, and, depending on S-arm length, maximally accelerated the reaction rate by 250-fold compared to the rate in the absence of copolymer. The copolymer permitted up to six nucleotides truncation of the S-arms having initial length of 10 and 11 nucleotides without loss of catalytic efficiency, enable tuning of the optimal temperature ranging from 30 to 55 °C. The approach might be useful for the development of DNAzyme systems targeting short or highly structured RNAs as well for improvement of DNAzyme-based nanomachines and biosensors.

Cationic copolymer-chaperoned DNAzyme sensor for microRNA detection

Multi-component nucleic acid enzymes (MNAzymes) are allosteric deoxyribozymes that are activated upon binding of a specific nucleic acid effector. MNAzyme activity is limited due to an insufficient assembly of the MNAzyme and its turnover. In this work, we describe the successful improvement of MNAzyme reactivity and selectivity by addition of cationic copolymers, which exhibit nucleic acid chaperone-like activity. The copolymer allowed a 210-fold increase in signal activity and a 95-fold increase in the signal-to-background selectivity of MNAzymes constructed for microRNA (miRNA) detection. The selectivity of the MNAzyme for homologous miRNAs was demonstrated in a multiplex format in which isothermal reactions of two different MNAzymes were performed. In addition, the copolymer permitted miRNA detections even in the presence of a ribonuclease which is ubiquitous in environments, indicating the protective effect of the copolymer against ribonucleases.

Investigation of cationized triblock and diblock poly(ε-caprolactone)-co-poly(ethylene glycol) copolymers for oral delivery of enoxaparin: In vitro approach

In this study, poly(ε-caprolactone)-co-poly(ethylene glycol) copolymers grafted with a cationic ligand, propargyltrimethyl ammonium iodide (PTA), to fabricate the cationized triblock (P(CatCLCL)₂-PEG) and diblock (P(CatCLCL)-mPEG) copolymers were investigated their potential use for oral delivery of enoxaparin (ENX). Influences of various PTA contents and different structures of the copolymers on molecular characteristics, ENX encapsulation, particle characteristics, and capability of drug transport across Caco-2 cells were elucidated. The results showed that P(CatCLCL)₂-PEG and P(CatCLCL)-mPEG copolymers self-aggregated and encapsulated ENX into spherical particles of ∼200-450nm. The increasing amount of PTA on the copolymers increased encapsulation efficiency of over 90%. The ENX release from both types of the cationized copolymer particles was pH-dependent which was retarded at pH 1.2 and accelerated at pH 7.4, supporting the drug protection in the acidic environment and possible release in the blood circulation. The toxicity of ENX-loaded particles on Caco-2 cells decreased when decreasing the amount of PTA. The triblock and diblock particles dramatically enhanced ENX uptake and transport across Caco-2 cells as compared to the ENX solution. However, the different structures of the copolymers slightly affected ENX transport. These results suggested that P(CatCLCL)₂-PEG and P(CatCLCL)-mPEG copolymers would be potential carriers for oral delivery of ENX.

STATEMENT OF SIGNIFICANCE

The anionic drugs such as proteins, peptides or polysaccharides are generally administered via invasive route causing patient incompliance and high cost of hospitalization. The development of biomaterials for non-invasive delivery of those drugs has gained much attention, especially for oral delivery. However, they have limitation due to non-biocompatibility and poor drug bioavailability. In this study, the novel poly(ε-caprolactone)-co-poly(ethylene glycol) copolymers grafted with propargyltrimethyl ammonium iodide, a small cationic ligand, were introduced to use as a carrier for oral delivery of enoxaparin, a highly negatively charged drug. The study showed that these cationized copolymers could achieve high enoxaparin entrapment efficiency, protect drug release in an acidic environment and enhance enoxaparin permeability across Caco-2 cells, the intestinal cell model. These characteristics of the cationized copolymers make them a potential candidate for oral delivery of anionic drugs for biomaterial applications.

Cooperative enhancement of deoxyribozyme activity by chemical modification and added cationic copolymer

Deoxyribozymes (DNAzymes) having RNA-cleaving activity have widely been explored as tools for therapeutic and diagnostic purposes. Both the chemical cleaving step and the turnover step should be improved for enhancing overall activity of DNAzymes. We have shown that cationic copolymer enhanced DNAzyme activity by increasing turnover efficacy. In this paper, effectｓ of the copolymer on DNAzymes modified with locked nucleic acids (LNA) or 2'-O-methylated (2'-OMe) nucleic acids were studied. The copolymer increased activity of these chemically modified DNAzymes. More than 30-fold enhancement in multiple-turnover catalytic activity was observed with 2'-OMe-modified DNAzyme in the presence of the copolymer. DNAzyme catalytic activity was successfully enhanced by cooperation of the added copolymer and chemical modification of DNAzyme.

Synthesis and properties of antifouling poly(CL-co-zDMAEMA) zwitterionic copolymer by one-step hybrid copolymerization

A novel biocompatible and biodegradable copolymer was synthesized by one-step hybrid copolymerization of ε-caprolactone (CL) and 2-(N,N-dimethylamino) ethyl methacrylate (DMAEMA) employing (1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phophoranylidenamino]-2Λ5,Λ5-catenadi(phosphazene) (t-BuP4) as a catalyst. The as-synthesized copolymer was betainizated resulting in a zwitterionic copolymer poly(CL-co-zDMAEMA) and the structure of the zwitterionic copolymer was confirmed by the FT-IR, NMR, and XPS measurements. The results of dynamic light scattering (DLS) show that this zwitterionic copolymer can self-assemble into stable micelles. The results of quartz crystal microbalance with dissipation (QCM-D) analysis and MTT measurement suggest that this zwitterionic copolymer possess better protein resistance and lower cell cytotoxicity in vitro in comparison with the cationic copolymer. The pyrene solubilization measurement of copolymers poly(CL-co-zDMAEMA) indicates an excellent pyrene solubilization capacity. These zwitterionic polymer micelles can release drugs in response to specific signals, such as temperature, pH, and enzymes and have a potential application in drug delivery and gene therapy due to their good antifouling, low cytotoxicity and high pyrene solubilization.