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January 2014 Archive

Posted by Chris on January 9th, 2014  ⟩  0 comments

One of our goals at GoldBio is to constantly review new products or product groups that we believe are beneficial to our scientists. Most recently, we added a line of protein labeling kits, either with biotin, streptavidin, HRP, or fluorophores (like CY3 and CY5). Since I have not worked a great deal with biotin labeling, and it’s typically subsequent streptavidin binding, I happily delved into the remarkable world of biotin-streptavidin research to find out more information.

Even in general, the biochemical interaction between this small bacterial protein and the essential vitamin is spectacular. The interaction between biotin and the various avidins is one of the strongest non-covalent bonding we have witnessed in nature, with a dissociation constant of over 10-14 M! So when these two molecules hook up, there’s not a lot that can separate them. Scientists have been utilizing this interaction since the 70’s, though it took us until almost 1990 before the crystal structure was discovered (and we started to truly understand why it’s so strong) and until the later 90’s to find a simpler method of dissociation to make the system even more robust. But for me, the why it works is less important than the ever-increasing number of how to use it.

Our available GoldBio kits are used more for general detection, purification or quantification of your proteins. Those are all very important and useful technologies and ones we’re excited to offer. Then there are scientists like Jung-Joon Min, Jong-Oh Park, and Sukho Park out of Chonnam National University in South Korea who are using the biotin-streptavidin interaction to build a drug delivery system (DDS) they are calling “bacteriobots”; a bacteria-driven and self-propelled, tumor-homing, chemotherapeautic fusion bomb!

The science all seems more sci-fi than real. It calls for utilizing the natural tendency of an attenuated version of the bacterium, Salmonella typhimurium (S. typhimurium), which is known to specifically drive toward and target various types of cancers (including breast and colorectal), as a microactuator and microsensor. They coated the bacteria’s surface with sulfhydryl-activated biotin and microbeads (which would optimally carry the chemotherapeutic agents) with streptavidin. Combining the two gives you something that looks like this:


Previously, there has been some exciting, new interest in a similar system that utilizes magnetotactic beads and a system of electromagnetic coiled springs to direct the bead movement. But these new bacteriobots seem superior in that they are self-propelled and the S. typhimurium selectively target and proliferate in the tumor cells they are intended to destroy. Overall, it’s reminiscent of fantastical stories of nanobots flooding around our bodies, continuously fixing and repairing our bodies to near immortality. This technology has only been tested insofar as its homing ability and proof of concept. The Chonnam group has not yet tested this system against tumors with actual chemotherapeutic agents to see if it will subsequently reduce the tumors as believed. But perhaps the fanstastical will become ordinary far sooner than we think.


Park, S. J., Park, S. H., Cho, S., Kim, D. M., Lee, Y., Ko, S. Y., Hong, Y., Choy, H.E., Min, J-J., Park, J-O., & Park, S. (2013). New paradigm for tumor theranostic methodology using bacteria-based microrobot. Scientific reports, 3.

Category Code: 79105 79101 88261

Posted by Chris on January 16th, 2014  ⟩  0 comments

Corals are fascinating and beautiful creatures. It’s also a fairly safe bet that most everyone would agree with that statement, judging from the millions of tourists and visitors to our world’s most famous coral reefs every year, and the billions in generated revenue those reefs provide to the countries which claim them. Coral reefs teem with abundant life, abundant colors (even ones in ranges which our poor eyes need help seeing), and abundant energy. These tiny Cnidarians, distant cousins of anemones and jelly fish, form the framework for some of the largest ecosystems on our planet with often as much or more diversification as a tropical jungle.

Yet, just as humans are integrally dependent on the bacteria that reside within us to survive, coral are just as dependent on a tiny algea called Symbiodinium. Symbiodinium comprise a large group of dinoflagellates, which is a group of marine, photosynthetic eukaryotes that includes algaes, protists and plankton. They become engulfed by the coral endoderm where they live on in a symbiotic relationship, providing photosynthetic nutrition in exchange for inorganic molecules they could not otherwise get. The system works amazingly well, but though studied extensively, is still quite mysterious. Even more important, our coral reefs are faced with various destructive dilemmas such as polluted or warming oceans, physical damage from the bottom scraping of fishing ships, carelessness of tourists…the list goes on. Warming trends have been known to cause a problem called “coral bleaching”. This bleaching is caused by a disassociation of the corals and Symbiodinium or a loss of chlorophyll within the algae. Bleaching also causes a host of other problems for the coral, increased disease, declined calcification, etc. that spells destruction for the ecosystem. Because of these problems, scientists are keen to better understand the relationship between host and symbiont.

Enter a group from the National Sun Yat-Sen University in Taiwan, under Chii-Shiarng Chen, who are delving into the protein interactions of these two organisms. They are studying the symbiotic gastrodermal cells (SGCs) which play an integral role in the association of the Symbiodinium and the coral endoderm. Using a similar approach to my blog story from last week, they harvested SGCs from amputated coral tentacles and utilized the biotin-streptavidin interaction to label the SGCs with biotin and later label the biotin with a green fluorescent streptavidin for confocal imaging. Further purification of the surface membrane proteins allowed for 2-D electrophoresis and LC-MS analysis which allowed them to distinguish 44 protein spots on the 2-D gel and identify 19 of the proteins through the LC-MS as molecular chaperons, actin filaments, involved in energy production or miscellaneous cellular functions!

While these results don’t explain the process of the symbiotic relationship between coral and Symbiodinium, it does begin to illuminate the players in the protein interactions that make the relationship work. With that background, Chen’s group (or other groups) can continue to blast away at this interaction, and by understanding, perhaps prevent more damage from occurring on one of the most marvelous and dynamic ecosystems our world has to offer.


Li, H. H., Huang, Z. Y., Ye, S. P., Lu, C. Y., Cheng, P. C., Chen, S. H., & Chen, C. S. (2014). Membrane Labeling of Coral Gastrodermal Cells by Biotinylation: The Proteomic Identification of Surface Proteins Involving Cnidaria-Dinoflagellate Endosymbiosis. PloS one, 9(1), e85119.

Category Code: 79101 88231

Posted by Chris on January 22nd, 2014  ⟩  0 comments

As I continue to search for novel and interesting applications for the interaction between biotin and streptavidin (check out my earlier blogs on bacteriobots and coral symbiotes), I love seeing the variety of applications that scientists from around the world dream up and develop! Most recently, I came across a paper describing a new method for DNA detection and fluorophore quenching using streptavidin-coated gold nanoparticles.

Chuan-Liang Feng et al. developed a system which utilized colloidal gold nanoparticles (AuNPs) to act as a DNA biosensors, or DNA probe, in order to detect DNA hybridization. Colloidal gold has been used for over a thousand years in various industries, starting with the glass blowers of ancient Rome and Greece who produced some truly amazing and beautiful, colored glass using gold particles dispersed throughout the glass to create light diffraction effects. One of the best known examples of this level of technology is the Lycurgus Cup (click here for another interesting article concerning this magnificent work of art). In our modern era, however, colloidal gold has become popular in the medical field, being investigated extensively as a drug carrier or in this case, gene therapy.

Streptavidin Gold Particle DNA detectionFeng’s novel approach in labeling the AuNPs with streptavidin and using its natural interaction with biotin to create a specific probe. Even more interesting, Feng used the association of biotin/avidin to build small, single-strand, complementary (or near complementary) DNA probes with either a biotin or Cy5 tail. Amazingly, the association, first between the biotin-ssDNA and the StAuNP, and the between the StAuNP/biotin-ssDNA and Cy5-ssDNA created a quenching effect on the fluorescence of the Cy5 molecule! Further, Feng’s group was able to add fully complementary, non-biotin ssDNA probes to the solution and slowly recover Cy5 fluorescence, outcompeting the near-complementary biotin-ssDNA and thus reversing the quenching effect!

This method is a simple and effective means to detect DNA hybridization, and as Feng reports, could be used as a high throughput method of biodiagnostics. Further tests will tell. One thing is for certain, scientists will continue to dream, create and develop new and ever-more fascinating systems to increase our understanding of the world we live in. And I, for one, cannot wait to see what we discover next.


Feng, C. L., Dou, X. Q., Liu, Q. L., Zhang, W., Gu, J. J., Zhu, S. M., Jenkins, A., & Zhang, D. (2013). Dual-Specific Interaction to Detect DNA on Gold Nanoparticles. Sensors, 13(5), 5749-5756.

Category Code: 79101 88231

Posted by Chris on January 29th, 2014  ⟩  1 comments

Fluorescent labeling is one of the most versatile tools that science has engineered over the last century. From DNA probes to protein labeling to immunoassays (like ELISAs) to microarray chips, fluorescent labeling has allowed us to see or detect the innermost workings of our world, the interactions of molecules without which we would not otherwise exist, and the tagging of millions of markers which are slowly (or rapidly, depending on your frame of reference) building our library of knowledge of DNA, proteins, inheritable traits and new, unique or evolving traits that define individuality.

Of the many inventions that are used daily in molecular biology (or just science in general), I think that I like the microarray the best! Maybe it was that the chips were becoming affordable and more widely used about the time that I started my science career. Or maybe it is the mind-numbingly huge number of things that can be answered or addressed at a single time by one teeny-weeny chip. Or maybe it was just that I enjoyed the beautiful, fluorescent spectrum of colors that appear almost as a strange Impressionist-meets-Abstract painting, but one that can finally be translated and interpreted to discover the real meaning behind the color combinations. Regardless, the technology is awesome!

Microarrays start with “the chip”. The first chip was an antibody microarray chip in the early 1980’s, invented by Tse Wen Chang. The basic premise was that a huge number of antibodies could be coated on a small surface area of a glass slide, which could then interact in an individual manner with a wide variety of antigens in order to see detailed and specific interactions that would otherwise be obscure in an ELISA test or Western blot. The microarray system has been reengineered and expanded many times since then, used now for protein interaction, DNA probing, tissue or histological studies and even organic compound chemical microarray. I’m sure that list can go on for quite a while further and I’d love to hear the research for which you’re specifically using microarray technology.


However, there is always room for improvements that may be made. In this case, a group from the Tokyo University of Technology think they’ve found a way to increase the sensitivity of the microarray glass chip even more. While this paper actually came out more than a year ago, I discovered it while searching for more, unique methods of utilizing biotin-streptavidin interactions. It’s always enjoyable when a new favorite study coincides with an old favorite!

Mitsuru Yasuda and Takuo Akimoto developed a method of creating a mirrored surface slide, called an Optical Interface Mirror (OIM) that has an optical interface (OI) layer on top of a plane surface mirror using silver (Ag) and aluminum oxide (Al2O3). To start, Yasuda and Akimoto aminated the OIM and coated the slide with biotin-NHS (you can find Gold Bio versions here). The slide was later washed with Streptavidin-Cy3 or Streptavidin-Cy5 in order to assess the level fluorescent detection compared to a basic glass slide. In short, they saw a fluorescence detection capability that was 2 orders of magnitude greater than a normal glass slide, a system which could potentially show us interactions or results that are simply too low to see currently on a standard microarray chip!

Innovations such as this one are what keep me excited about being in the science field and also excited to be part of a company like Gold Bio which strives to foster those kind of innovations by reducing the cost of the experiments. I can only imagine what will be discovered tomorrow…


Yasuda, M., & Akimoto, T. (2012). Highly Sensitive Fluorescence Detection of Avidin/Streptavidin with an Optical Interference Mirror Slide. Analytical Sciences, 28(10), 947-952.

Category Code: 79101 88231