Key Points
- Chinese researchers developed a highly sensitive and selective colorimetric sensor using a cobalt-platinum graphitic nanozyme (CoPt@G) to visually detect vitamin C in commercial beverages.
- The sensor showed strong performance, with a wide detection range (5–60 μM), low detection limit (1.4 μM), and high accuracy (95.2%–104.3% recovery rates) in juice products.
- This innovation could benefit food manufacturers, health professionals, and consumers, and may be adapted in the future for detecting other nutrients or contaminants.
A team of Chinese researchers recently examined a new method that can detect vitamin C in commercial beverages. This new sensor, which is a highly selective and sensitive colorimetric sensor, was demonstrated by the researchers to be able to detect the vitamin in beverage products using a new nanozyme-based platform. The findings of this study, which were published in the journal Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, advance a new way to monitor the nutritional value of products (1).
What is Vitamin C?
Vitamin C, also known as ascorbic acid (AA), is a key nutrient found in foods and beverages. It is an essential antioxidant that protects cells from free radical damage, supports iron absorption, and may help prevent diseases like cancer and heart disease (2). Since the body can't produce it, vitamin C must be obtained through diet, mainly through fruits and vegetables, or supplements like capsules and chewable tablets (2).
When vitamin C is ingested in the human body, it helps perform several functions in human metabolism, including collagen synthesis, immune function, and the maintenance of skin and vascular health (1). Unfortunately, vitamin C is highly prone to oxidative degradation during food processing, packaging, storage, and transportation, often leading to a reduction in its bioavailability by the time a product reaches consumers (1).
What is the sensor the researchers developed in the study?
In their study, the researchers proposed a new peroxidase (POD)-like nanozyme constructed from cobalt-platinum encapsulated in a graphitic shell, which is abbreviated as CoPt@G (1). This nanozyme was synthesized via a one-pot chemical vapor deposition (CVD) method and used as the central component of a simple, fast, and visual AA detection system (1).
Using nanozyme technology, the research team was able to mimic natural enzyme activity using nanomaterials. Nanozymes offer numerous advantages such as excellent chemical stability, ease of mass production, and high cost-effectiveness. Most nanozymes suffer from low activity under neutral conditions and poor long-term stability, which are two major limitations for practical applications (1).
How did the CoPt@G nanozyme overcome these challenges?
The researchers designed the CoPT@G nanozyme to overcome the stability and low activity under neutral condition challenges. First, the researchers gave the nanozyme a graphitic shell, which improved its structural robustness and catalytic activity. This allowed the material to maintain high enzymatic activity across a wide range of pH levels and temperatures, even after prolonged storage (1).
Second, the CoPt@G nanozyme was designed to catalyze hydrogen peroxide (H₂O₂) to produce reactive oxygen species that oxidize the colorless substrate 3,3′,5,5′-tetramethylbenzidine (TMB) into a vibrant blue compound known as oxidized TMB (oxTMB) (1). When AA was introduced, it reduced the oxTMB, which caused a visible color change (1). This color shift, detectable by the naked eye or with simple optical instrumentation, enabled quick and reliable quantification of AA levels (1).
What were the results of the study?
The researchers showed that their colorimetric sensor demonstrated a broad linear detection range from 5 to 60 μM and a low detection limit of 1.4 μM (signal-to-noise ratio = 3), placing it on par with or better than most existing vitamin C detection techniques (1). Moreover, it showed excellent selectivity, unaffected by common interfering substances like metal ions, small biomolecules, and other antioxidants.
The sensor was tested on orange, grape, and lemon juice products. The researchers found that the recovery rates ranged between 95.2% and 104.3%, affirming the sensor’s precision and reliability in complex food matrices (1).
What are the implications of this study?
This study has several key implications. For example, apart from benefiting food manufacturers and quality assurance professionals, the sensor could also serve healthcare providers, nutritionists, and consumers seeking more transparency in the nutritional content of their purchases (1).
With this research, the team has set the stage for broader applications of nanozyme-mediated colorimetric detection in the food industry. Future developments could adapt the CoPt@G platform to detect other key nutrients or contaminants, reinforcing the growing role of nanotechnology in food safety and public health (1).
References
- Sun, X.; Wang, S.; Gui, G.; Li, S. Graphitic Nanozyme for Visual Ascorbic Acid Sensing in Commercial Beverages. Spectrochimica Acta Part A: Mol. Biomol. Spectrosc. 2026, 344 Part 2, 126724. DOI: 10.1016/j.saa.2025.126724
- Mayo Clinic Staff, Vitamin C. Mayo Clinic Staff. Available at: https://www.mayoclinic.org/drugs-supplements-vitamin-c/art-20363932 (accessed 2025-07-30).
