Pullulan Encapsulation of Labile Biomolecules to Give Stable Bioassay Tablets

Abstract

A simple and inexpensive method is reported for the long-term stabilization of enzymes and other unstable reagents in premeasured quantities in water-soluble tablets (cast, not compressed) made with pullulan, a nonionic polysaccharide that forms an oxygen impermeable solid upon drying. The pullulan tablets dissolve in aqueous solutions in seconds, thereby facilitating the easy execution of bioassays at remote sites with no need for special reagent handling and liquid pipetting. This approach is modular in nature, thus allowing the creation of individual tablets for enzymes and their substrates. Proof-of-principle demonstrations include a Taq polymerase tablet for DNA amplification through PCR and a pesticide assay kit consisting of separate tablets for acetylcholinesterase and its chromogenic substrate, indoxyl acetate, both of which are highly unstable. The encapsulated reagents remain stable at room temperature for months, thus enabling the room-temperature shipping and storage of bioassay components.

Target‐Induced and Equipment‐Free DNA Amplification with a Simple Paper Device

“…[16] Thes ensors were prepared as follows ( Figure 4A): 1) printing of aD NA capture sequence (DC2) on paper microzones,2)mixing apullulan solution with RCAr eagents containing ac ircular DNAt emplate (CDT3), f29DP, [16] Thes ensors were prepared as follows ( Figure 4A): 1) printing of aD NA capture sequence (DC2) on paper microzones,2)mixing apullulan solution with RCAr eagents containing ac ircular DNAt emplate (CDT3), f29DP, …”

Integrating graphene oxide, functional DNA and nucleic-acid-manipulating strategies for amplified biosensing

“…Keeping an enzyme highly active requires low-temperature storage and measuring an adequate amount of enzyme from a stock solution is not always a trivial task, further hampering the potential of such sensors for field applications. A simple solution might be to use tablets made from the polymeric sugar pullulan, which we recently demonstrated as a platform for production of reagent tablets with pre-determined enzyme activity [74]. Such tablets can provide exceptional protection to enzymes when stored at ambient temperatures, but rapidly dissolve in water to release highly-active biological agents.…”

A DNAzyme‐Based Colorimetric Paper Sensor for Helicobacter pylori

“…[13] Thes econd reason was based on our observation that the addition of the sample to the sensor zone caused significant capillary-driven flow toward the other two zones (see the liquid flow using amodel dye solution in Figure S4 a). There are two reasons for the use of the pullulan films.F irst, as we have shown previously,p ullulan film formation provides long-term stability to entrapped macromolecules including protein enzymes and RNA-containing nucleic acids.…”