Blunt-end vectors generated by polymerase chain reaction (PCR) for direct cloning of blunt-end DNA fragments

Blunt-end cloning is a convenient way to clone polymerase chain reaction (PCR) products generated by proof-reading DNA polymerase. However, it is a time consuming procedure to prepare the linearized blunt-end vector, which usually involves plasmid extraction and restriction enzyme digestion. Moreover, 5’ dephosporylation of the vector is usually required to avoid vector self-ligation. Here, we reported a method for generating linearized blunt-end vector pBSK-blunt by PCR. Vector generated in this way has no 5’-phosphate groups, hence completely avoiding vector self-ligation and yielding almost 100% positive clones.Key words: Blunt-end cloning, phosphorylated DNA fragment, dephosphorylated blunt-end vector

Microfluidic-Generated Biopolymer Microparticles as Cargo Delivery Systems

Droplet microfluidics offers precise and simultaneous control of multiple fluids at microscale, which enables synthesis of novel microparticles with compositional and structural diversity in a controllable way. The morphology and functionality of generated microparticles can be well designed by modulating the hydrodynamic profile as well as geometric structures. The synergistic combination of droplet microfluidics with biodegradable materials makes it possible to encapsulate actives/drugs inside microparticles at high efficiency for drug delivery. The utilization of these microfluidic-generated microparticles with the characteristics of easy biodegradability and good biocompatibility in the field of drug delivery has made considerable progress in recent years. In this review, the commonly used structures of microchannel and methods to generate microparticles with droplet microfluidics are introduced. In addition, recent advances of biodegradable microparticles in the application of drug delivery are discussed and summarized with the focus on two kinds of biopolymers for preparing biodegradable microspheres, natural biopolymers, and synthetic biopolymers. Next, environment-sensing microencapsulation systems have been discussed because of their ability to release drug upon external stimulation, thereby allowing on-demand drug delivery. Finally, current challenges of utilizing microparticles in drug delivery are pointed out and some perspectives for the future direction in research and applications are provided

SERS biosensors based on cucurbituril-mediated nanoaggregates for wastewater-based epidemiology

Hierarchical self-assembly of nanoparticles (NPs) mediated by macrocyclic molecules, cucurbiturils (CBs), provides a facile method to fabricate surface-enhanced Raman spectroscopy (SERS) sensors for potential applications in biosensing and environmental monitoring. In contrast to conventional techniques for wastewater-based epidemiology (WBE), CB-NP SERS sensors offer great opportunities for on-site quantification of trace chemical and biological markers due to its high sensitivity, selectivity, reproducibility, multiplexing capability and tolerance against contamination. The working principles of the CB-Au NP nanocomposites including fabrication, sensing mechanisms and structure-property relationships are explained while the design guidelines and selected examples of CB-Au NP SERS sensors are discussed. The review concludes by highlighting recent advances in this area and exploring opportunities in the context of WBE

Microbial community analysis of fresh and old microbial biofilms on Bayon Temple sandstone of Angkor Thom, Cambodia

The temples of Angkor monuments including Angkor Thom and Bayon in Cambodia and surrounding countries were exclusively constructed using sandstone. They are severely threatened by biodeterioration caused by active growth of different microorganisms on the sandstone surfaces, but knowledge on the microbial community and composition of the biofilms on the sandstone is not available from this region. This study investigated the microbial community diversity by examining the fresh and old biofilms of the biodeteriorated bas-relief wall surfaces of the Bayon Temple by analysis of 16S and 18S rRNA gene sequences. The results showed that the retrieved sequences were clustered in 11 bacterial, 11 eukaryotic and two archaeal divisions with disparate communities (Acidobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Proteobacteria; Alveolata, Fungi, Metazoa, Viridiplantae; Crenarchaeote, and Euyarchaeota). A comparison of the microbial communities between the fresh and old biofilms revealed that the bacterial community of old biofilm was very similar to the newly formed fresh biofilm in terms of bacterial composition, but the eukaryotic communities were distinctly different between these two. This information has important implications for understanding the formation process and development of the microbial diversity on the sandstone surfaces, and furthermore to the relationship between the extent of biodeterioration and succession of microbial communities on sandstone in tropic region. © 2010 The Author(s).published_or_final_versionSpringer Open Choice, 01 Dec 201

A multiple exp-function method for nonlinear differential equations and its application

A multiple exp-function method to exact multiple wave solutions of nonlinear partial differential equations is proposed. The method is oriented towards ease of use and capability of computer algebra systems, and provides a direct and systematical solution procedure which generalizes Hirota's perturbation scheme. With help of Maple, an application of the approach to the $3+1$ dimensional potential-Yu-Toda-Sasa-Fukuyama equation yields exact explicit 1-wave and 2-wave and 3-wave solutions, which include 1-soliton, 2-soliton and 3-soliton type solutions. Two cases with specific values of the involved parameters are plotted for each of 2-wave and 3-wave solutions.Comment: 12 pages, 16 figure