Silver Framework and Carbon Black Team Up to Detect Heart Drug Ticagrelor at Trillionth-of-a-Mole Levels

Scientists have built a remarkably sensitive electrochemical sensor that can detect the widely prescribed antithrombotic drug ticagrelor at concentrations as low as 0.0033 nanomolar, a level corresponding to trillionths of a mole per liter. The new platform, described in the journal Results in Chemistry, relies on a nanocomposite made by combining a silver-based metal-organic framework with carbon black, two inexpensive materials whose complementary properties turn out to be far more powerful together than either is alone. The work, led by Mahmoud Roushani, Zahra Mirzaei Karazan, and Ishaq Saleh Makki, demonstrates not only record-level sensitivity in the laboratory but also reliable performance in spiked human serum samples, hinting at a practical route toward fast, low-cost monitoring of a drug whose dosing window can be a matter of life and death.

Ticagrelor is a mainstay of modern cardiology. It works by reversibly blocking the platelet P2Y12 receptor, which prevents adenosine diphosphate from activating platelets and triggering the clotting cascade. Physicians prescribe it, often alongside aspirin, to patients with acute coronary syndrome or ST-segment elevation myocardial infarction to ward off further thrombotic events. Because the drug’s therapeutic effect depends on careful dosing and because patients differ widely in how they metabolize it, analytical methods that can measure ticagrelor quickly and accurately are clinically valuable. Until now, that job has mostly fallen to chromatography-based techniques such as high-performance liquid chromatography, liquid chromatography coupled with mass spectrometry, reverse-phase HPLC, and various spectrophotometric and bio-analytical approaches. These methods are accurate but typically require expensive instrumentation, trained operators, lengthy sample preparation, and centralized laboratory facilities.

Electrochemical sensing offers an appealing alternative. By translating molecular interactions at an electrode surface into an electrical current, such sensors can be fast, cheap, portable, and sensitive. The catch is that a bare electrode rarely provides enough signal for trace-level detection of a drug in a complex biological matrix. The standard remedy is to coat the electrode with a nanomaterial or nanocomposite that boosts conductivity, surface area, and catalytic activity. The Iranian-led team behind the new study chose an unusual pairing: carbon black, an abundant and highly conductive industrial carbon, and a silver-based metal-organic framework, a crystalline coordination network built from silver ions and the organic linker 1,3,5-benzenetricarboxylic acid.

Each component brings distinct strengths. Carbon black offers excellent porosity, high surface area, strong electrical conductivity, and a wide potential window, making it an ideal conductive backbone. Metal-organic frameworks, meanwhile, are prized for their enormous surface areas, tunable structures, and high porosity, all of which improve the interface between electrode and electrolyte. In this system, the silver framework performs three critical jobs: it supplies metal-based catalytic activity, it acts as an intrinsic electrochemical signal source through its own silver-related redox chemistry, and its tunable porosity facilitates molecular diffusion while enlarging the effective surface area available for recognition events. The researchers synthesized the framework by dissolving the organic linker and silver nitrate separately in methanol, combining the solutions, and heating the mixture at 120 degrees Celsius overnight, a straightforward and economical preparation.

Microscopy and spectroscopy confirmed that the marriage worked. Field-emission scanning electron microscopy showed carbon black forming a spherical film-like coating, while the silver framework appeared as sheet-like crystals with sharp, regular morphologies. In the composite, the two components merged into a porous, spongy, interconnected architecture with no phase separation, exactly the kind of structure that maximizes both conductivity and accessible surface area. Energy-dispersive X-ray analysis and elemental mapping verified that carbon, oxygen, nitrogen, and silver were uniformly distributed throughout the material. Fourier-transform infrared spectroscopy revealed characteristic bands from the aromatic linker and carboxylate groups, and X-ray diffraction showed that the framework’s crystalline structure survived composite formation intact, with no detectable separate crystalline silver oxide or metallic silver impurity phases.

Electrochemical tests then revealed why the composite outperforms its ingredients. Using cyclic voltammetry and electrochemical impedance spectroscopy with a ferricyanide redox probe, the team found that adding carbon black to a glassy carbon electrode increased current and lowered charge-transfer resistance from 687 ohms for the bare electrode to 344 ohms. The silver framework alone, hampered by its intrinsically low conductivity, actually raised resistance to 2016 ohms. But the combined composite slashed resistance to just 221 ohms, clear evidence of synergy. Calculations based on the Randles-Sevcik equation showed the composite electrode’s electrochemically active surface area reached 0.045 square centimeters, more than double the 0.021 square centimeters of the bare electrode.

Perhaps the most intriguing finding concerns how the sensor actually detects ticagrelor. Neither the bare electrode nor the carbon-black-modified electrode produced a distinct response to the drug. Instead, the signal originates from the silver-containing framework itself: the drug, with its sulfur-, nitrogen-, and oxygen-containing functional groups, accumulates on the electrode through affinity interactions with accessible silver sites and hydrogen bonding with the organic linker, thereby blocking the electroactive silver sites and suppressing the silver-related current. The result is an indirect, signal-off mechanism in which the drug’s presence is measured by how much it dampens the baseline signal. Carbon black amplifies this effect dramatically. The drug-induced current change was approximately 519 microamperes at the composite electrode versus 196 microamperes at the framework alone, a roughly 2.6-fold enhancement, because the conductive carbon network improves electron transfer between the electroactive silver sites and the underlying electrode while also dispersing the framework particles more effectively.

After optimizing the composite ratio, buffer pH, and salt concentration, the sensor delivered striking analytical performance. Differential pulse voltammetry yielded a linear response across an extraordinarily wide concentration range spanning 0.01 to 2500 nanomolar, with a correlation coefficient of 0.9983 and a calculated detection limit of 0.0033 nanomolar. For comparison, previously reported ticagrelor sensors based on carbon paste electrodes modified with multiwalled carbon nanotubes and titanium nanoparticles, zeolite-modified carbon paste, or solid gold electrodes achieved detection limits in the hundreds of nanomolar to micromolar range. The authors caution that such cross-study comparisons should be interpreted carefully, since electrode architectures, sample preparation, and detection-limit calculations differ, but the numbers nonetheless underline the platform’s analytical promise. Microscopy before and after testing also confirmed the composite’s structural stability under operating conditions.

The sensor proved robust in the ways that matter for real-world use. It tolerated high concentrations of structurally related drugs and common biological interferents, including ticlopidine, clopidogrel, warfarin, ascorbic acid, dopamine, uric acid, and glucose. Five identical electrodes produced responses with a relative standard deviation of just 2.5 percent, and five repeated measurements on a single electrode gave 3.1 percent. After fifteen days of storage at room temperature, the electrode retained 93 percent of its initial response, and fifty consecutive voltammetric cycles preserved 95.32 percent of the original signal. Most importantly, when the team spiked human serum samples with 50, 100, and 200 nanomolar ticagrelor after protein precipitation, the sensor recovered between 99.5 and 101.2 percent of the added drug with relative standard deviations below 2.8 percent, demonstrating that the platform can function in a genuine biological matrix rather than only in pristine buffer solutions.

The broader significance of the work lies in its demonstration that cheap, readily available materials can be engineered into sensors rivaling far costlier analytical instruments. Carbon black costs pennies, the silver framework is synthesized in a single overnight reaction, and the entire electrode modification involves ultrasonicating the two powders in a drop of solvent and drying five microliters onto a glassy carbon electrode. A sensor built this way could, in principle, support point-of-care or bedside monitoring of ticagrelor, helping clinicians tailor antiplatelet therapy to individual patients and detect abnormal drug levels before they translate into bleeding or clotting complications. The signal-off design, in which the analyte suppresses a built-in silver redox signal, also offers a template that other researchers could adapt to different drug molecules capable of binding silver sites. While further validation in larger clinical studies would be needed before any diagnostic deployment, the study adds a compelling entry to the growing toolkit of metal-organic framework sensors and shows how the right nanoscale partnership can turn an ordinary electrode into an extraordinarily perceptive one.

Subject of Research: Electrochemical detection of the antithrombotic drug ticagrelor using a silver metal-organic framework and carbon black nanocomposite-modified electrode

Article Title: Electrochemical sensor based on Ag-metal organic framework/carbon black nanocomposite for the selective detection of Ticagrelor

Article References: Roushani, M., Karazan, Z. M., & Makki, I. S. (2026). Electrochemical sensor based on Ag-metal organic framework/carbon black nanocomposite for the selective detection of Ticagrelor. Results in Chemistry, 31, Article 103939. https://doi.org/10.1016/j.rechem.2026.103939

Image Credits: AI Generated

DOI: 10.1016/j.rechem.2026.103939

Keywords: ticagrelor, electrochemical sensor, metal-organic framework, carbon black, nanocomposite, glassy carbon electrode, antithrombotic drug, differential pulse voltammetry, human serum, detection limit, silver framework, P2Y12 receptor