Tag Archives: Institute for Basic Science (IBS)

A pumpkin-shaped molecule for the first real-time methamphetamine and amphetamine sensor

A Sept. 28,2017 news item on Nanowerk announces a portable, inexpensive sensor for drugs (Note: A link has been renewed),

Speed, uppers, chalk, glass, crystal, or whatever you prefer to call them, can be instantly detected from biological fluids with a new portable kit that costs as little as $50. Scientists at the Center for Self-Assembly and Complexity, within the Institute for Basic Science (IBS, South Korea), in collaboration with Pohang University of Science and Technology (POSTECH), have devised the first methamphetamine and amphetamine sensor that can detect minute concentrations of these drugs from a single drop of urine in real-time.

Published in the journal Chem (“Point-of-Use Detection of Amphetamine-Type Stimulants with Host-Molecule-Functionalized Organic Transistors”), this simple and flexible sensor, which can be attached to a wristband and connected to an Android app via Bluetooth, could move drug screening from the labs to the streets.

A Sept. 28 (?), 2017 IBS press release by Letizia Diamante (also on EurekAlert), which originated the news item, expands on the theme,

Easy to synthesize and cheaper than heroin or cocaine, amphetamine-based drugs are the most abused drugs in the world, after cannabis. Conventional drug detection methods require a long time, as the sample must be taken into a lab for the analysis. It also needs experts to run the expensive equipment. The technology reported in this study is instead small, portable, cheap, fast and easy to use.

The idea for this technology came from the IBS chemist HWANG Ilha: “I was watching a TV news report on the usage of illegal drugs, and I thought to check what the chemical structure of methamphetamine looks like.” Soon after, the scientist anticipated that the drug would form a tight complex with a family of hollow pumpkin-shaped molecules, called cucurbituril (CB) members. The team then discovered that cucurbit[7]uril (CB[7])’s empty cavity binds well with amphetamine-based drugs and can be used as the drug recognition unit of a sensor. Cucurbiturils’ hollow chamber has already been studied for various technological uses, but this is the first device application in amphetamine-based drug detection.


▲ Figure 1: Wireless sensor for amphetamine-based drug detection.The kit is made of an organic field-effect transistor (OFET) device, an electric circuit board with a rechargeable battery and an antenna. The OFET device surface is coated with CB[7], whose function is to bind amphetamine and methamphetamine drugs in solution. The binding event is instantly converted to current, whose magnitude is proportional to the concentration of the drug. The app on the smartphone shows a peak as soon as a drop of urine with the drug is applied to the device. Moreover the entire kit can fit in a handy wristband.


▲ Video 1: The detector in action.
[Click text not image]
As soon as a drop of water with 0.0001 ng/mL (1 pM) of amphetamine is applied to the kit, the app shows a peak in current proportional to the concentration of drug. When the liquid is removed, the current level goes back to baseline, and the sensor can be reused. (Modified from Jang et al, Chem 2017)

Combining a transistor coated with CB[7], flexible materials, rechargeable batteries and a Bluetooth antenna, the research team developed a detector wristband connected to an app. In the presence of the drug, the molecular recognition between CB[7] and the drug molecule triggers an electrical signal which appears as a peak on the smartphone screen.

Current drug detection based on immunoassay or liquid chromatography/mass spectrometry techniques has a detection limit of about 10 ng/mL. On the contrary, the sensitivity of this new sensor is about 0.0001 ng/mL in water and 0.1 ng/mL in urine. Therefore, it is expected that this method will allow the detection of drug molecules in biological fluids, like urine and sweat, for a longer time after drug consumption.


▲ Figure 2: Graphic representation of the drug detection platform.Binding of drug molecules to the hollow cucurbit[7]uril (CB[7])’s cavity changes the current signal flowing in the transistor and therefore can be used as a detection system. The molecular structure of amphetamine and methamphetamine bound to cucurbit[7]uril (CB[7]) was confirmed with X-ray crystallography. Each color indicates a different atom (blue: nitrogen, red: oxygen, gray: carbon, and white: hydrogen). CB[7]’s hydrogen atoms have been omitted for clarity.


▲ Figure 3: Humorous view of the pumpkin-shaped molecule, cucurbit[7]uril (CB[7]), able to bind and detect amphetamine and methamphetamine molecules.(Credits: Modified from Titusurya – Freepik.com)

“Real time detection of amphetamine drugs on location would bring a big change to society,” explains another corresponding author KIM Kimoon. “In the same way as police can use a breathalyzer to detect alcohol on the spot, we aim to achieve the same with this device.”

False positives cannot be excluded yet, as urine contains a rich mixture of proteins and other metabolites that could affect the reading. Therefore, before commercializing it, clinical trials with drug users’ biological fluids are necessary. The researchers have patented the technology and they will continue to do further research in the near future.s

“Combining basic science with the latest technology, we can expect that this research will also lead to other new sensors, useful for our daily life,” concludes the third corresponding author OH Joon Hak. Indeed, the team is also keen on developing sensors for other kinds of drugs, as well as kits for the detection of dangerous substances, environmental monitoring, healthcare and safety.

Here’s a link to and a citation for the paper,

Point-of-Use Detection of Amphetamine-Type Stimulants with Host-Molecule-Functionalized Organic Transistors by Yoonjung Jang, Moonjeong Jang, Hyoeun Kim, Sang Jin Lee, Eunyeong Jin, Jin Young Koo, In-Chul Hwang, Yonghwi Kim, Young Ho Ko, Ilha Hwang., Joon Hak Oh, Kimoon Kim. Chem (2017). DOI: 10.1016/j.chempr.2017.08.015 Publication stage: In Press Corrected Proof

This paper appears to be behind a paywall.

Wearable device to monitor and control diabetes is based on graphene

The research comes from Korea’s Institute of Basic Science and was announced in a March 22, 2016 news article by Lee Chi-dong for Yonhap News Agency,

A team of South Korean scientists announced Tuesday [March 22, 2016] that they have developed a wearable device, based on nanotechnology, for more convenient diabetes monitoring and therapy.

The graphene-using “smart patch” has improved the accuracy of blood sugar level measurements as it checks not only glucose in sweat but also temperature and acidity, according to the Institute for Basic Science (IBS) located in Daejeon, some 160 kilometers south of Seoul.

Existing smart patches gauge blood sugar merely in sweat.

Google is working on “smart contact lens” with an ultra-tiny super sensitive glucose sensor for tear fluid. Its accuracy remains a question amid concerns about adverse effects on eye health.

A March 21, 2016 IBS press release on EurekAlert provides more details about the work,

A scientific team from the Center for Nanoparticle Research at IBS has created a wearable GP [graphene]-based patch that allows accurate diabetes monitoring and feedback therapy by using human sweat. The researchers improved the device’s detecting capabilities by integrating electrochemically active and soft functional materials on the hybrid of gold-doped graphene and a serpentine-shape gold mesh. The device’s pH and temperature monitoring functions enable systematic corrections of sweat glucose measurements as the enzyme-based glucose sensor is affected by pH (blood acidity levels) and temperature.

Diabetes and regulating glucose levels

Insulin is produced in the pancreas and regulates the use of glucose, maintaining a balance in blood sugar levels. Diabetes causes an imbalance: insufficient amounts of insulin results in high blood glucose levels, known as hyperglycemia. Type 2 diabetes is the most common form of diabetes with no known cure. It affects some 3 million Koreans with the figure increasing due to dietary patterns and an aging society. The current treatments available to diabetics are painful, inconvenient and costly; regular visits to a doctor and home testing kits are needed to record glucose levels. Patients also have to inject uncomfortable insulin shots to regulate glucose levels. There is a significant need for non-invasive, painless, and stress-free monitoring of important markers of diabetes using multifunctional wearable devices. The IBS device facilitates this and thereby reduces the lengthy and expensive cycles of visiting doctors and pharmacies.

Components of the graphene-based wearable device

KIM Dae-Hyeong, a scientist from the Center for Nanoparticle Research, describes the vast array of components: “Our wearable GP-based device is capable of not only sweat-based glucose and pH monitoring but also controlled transcutaneous drug delivery through temperature-responsive microneedles. Precise measurement of sweat glucose concentrations are used to estimate the levels of glucose in the blood of a patient. The device retains its original sensitivity after multiple uses, thereby allowing for multiple treatments. The connection of the device to a portable/ wireless power supply and data transmission unit enables the point-of-care treatment of diabetes.” The professor went on to describe how the device works, “The patch is applied to the skin where sweat-based glucose monitoring begins on sweat generation. The humidity sensor monitors the increase in relative humidity (RH). It takes an average of 15 minutes for the sweat-uptake layer of the patch to collect sweat and reach a RH over 80% at which time glucose and pH measurements are initiated.”

Merits of the device and drug administration

The device shows dramatic advances over current treatment methods by allowing non-invasive treatments. During the team’s research, two healthy males participated in tests to demonstrate the sweat-based glucose sensing of the device. Glucose and pH levels of both subjects were recorded; a statistical analysis confirmed the reliable correlation between sweat glucose data from the diabetes patch and those from commercial glucose tests. If abnormally high levels of glucose are detected, a drug is released into a patient’s bloodstream via drug loaded microneedles. The malleable, semi-transparent skin-like appearance of the GP device provides easy and comfortable contact with human skin, allowing the sensors to remain unaffected by any skin deformations. This enables stable sensing and efficient drug delivery.

The scientific team also demonstrated the therapeutic effects by experimenting on diabetic (db/db) mice. Treatment began by applying the device near the abdomen of the db mouse. Microneedles pierced the skin of the mouse and released Metformin, an insulin regulating drug, into the bloodstream. The group treated with microneedles showed a significant suppression of blood glucose concentrations with respect to control groups. “One can easily replace the used microneedles with new ones. Treatment with Metformin through the skin is more efficient than that through the digestive system because the drug is directly introduced into metabolic circulation through the skin,” commented KIM Dae-Hyeong. He went on: “These advances using nanomaterials and devices provide new opportunities for the treatment of chronic diseases like diabetes.”

The researchers have made an image illustrating their work available,

Caption: Optical image of the GP-hybrid electrochemical device array on the human skin Credit: IBS

Caption: Optical image of the GP-hybrid electrochemical device array on the human skin Credit: IBS

Here’s a link to and a citation for the paper,

A graphene-based electrochemical device with thermoresponsive microneedles for diabetes monitoring and therapy by Hyunjae Lee, Tae Kyu Choi, Young Bum Lee, Hye Rim Cho, Roozbeh Ghaffari, Liu Wang, Hyung Jin Choi, Taek Dong Chung, Nanshu Lu, Taeghwan Hyeon, Seung Hong Choi, & Dae-Hyeong Kim. Nature Nanotechnology (2016) doi:10.1038/nnano.2016.38 Published online 21 March 2016

This paper is behind a paywall.

The birth of a molecule

This research comes from Korea’s Institute of Basic Science in a Feb. 27, 2015 news item on Azonano,

The research team of the Center for Nanomaterials and Chemical Reactions at the Institute for Basic Science (IBS) has successfully visualized the entire process of bond formation in solution by using femtosecond time-resolved X-ray liquidography (femtosecond TRXL) for the first time in the world.

A Feb. 18, 2015 IBS press release, which originated the news item, provides more details,

Every researcher’s longstanding dream to observe real-time bond formation in chemical reactions has come true. Since this formation takes less than one picosecond, researchers have not been able to visualize the birth of molecules.

The research team has used femtosecond TRXL in order to visualize the formation of a gold trimer complex in real time without being limited by slow diffusion.

They have focused on the process of photoinduced bond formation between gold (Au) atoms dissolved in water. In the ground (S0) state, Au atoms are weakly bound to each other in a bent geometry by van der Waals interactions. On photoexcitation, the S0 state rapidly converts into an excited (S1) state, leading to the formation of covalent Au-Au bonds and bent-to-linear transition. Then, the S1 state changes to a triplet (T1) state with a time constant of 1.6 picosecond, accompanying further bond contraction by 0.1 Å. Later, the T1 state of the trimer transforms to a tetramer on nanosecond time scale, and Au atoms return to their original bent structure.

“By using femtosecond TRXL, we will be able to observe molecular vibration and rotation in the solution phase in real time,” says Hyotcherl Ihee, the group leader of the Center for Nanomaterials at IBS, as well as the professor of the Department of Chemistry at Korea Advanced Institute of Science and Technology.

Here’s a link to and a citation for the paper,

Direct observation of bond formation in solution with femtosecond X-ray scattering by Kyung Hwan Kim, Jong Goo Kim, Shunsuke Nozawa, Tokushi Sato, Key Young Oang, Tae Wu Kim, Hosung Ki, Junbeom Jo, Sungjun Park, Changyong Song, Takahiro Sato, Kanade Ogawa, Tadashi Togashi, Kensuke Tono, Makina Yabashi, Tetsuya Ishikawa, Joonghan Kim, Ryong Ryoo, Jeongho Kim, Hyotcherl Ihee & Shin-ichi Adachi. Nature 518, 385–389 (19 February 2015) doi:10.1038/nature14163 Published online 18 February 2015

This paper is behind a paywall although there is a free preview via ReadCube access.