Ultrasonically Polyhydroxylated C60 (Fullerenol)

  • Water-soluble polyhydroxylated C60 fullerene, called fullerenol or fullerol, is a strong free radical scavenger and is therefore used as an antioxidant in supplements and pharmaceuticals.
  • Ultrasonic hydroxylation is a rapid and simple one-step reaction, which is used to produce water-soluble polyhydroxylated C60.
  • Ultrasonically synthesized water-soluble C60 has superior quality and is used for pharma and high performance applications.

Ultrasonic One-Step Synthesis of Polyhydrolxylated C60

Ultrasonic cavitation is the superior technique to produce high-quality polyhydroxylated C60 fullerenes, which are water-soluble and can be therefore used in various applications in pharma, medicine and industry. Afreen et al (2017) have developed a rapid and simple ultrasonic synthesis of contamination-free polyhydroxylated C60 (also known as fullerenol or fullerol). The ultrasonic one-step reaction uses H2O2 and is free from the use of additional hydroxylating reagents, i.e. NaOH, H2SO4, and phase transfer catalysts (PTC), which cause impurities in the synthesized fullerenol. This makes the ultrasonic fullerenol synthesis is a cleaner approach to produce fullerenol; at the same time, it is an easier and a faster way to produce high-quality, water-soluble C60.

Ultrasonic hydroxylation of C60 to produce water-soluble c60 (fullerenol)

Possible reaction paths in the ultrasound-assisted synthesis of fullerenol in the presence of dil. H2O2 (30%).
source: Afreen et al. 2017

Ultrasonic Synthesis of Water-Soluble C60 – Step-by-Step

UP200St - 200W powerful ultrasonic processorFor the fast, simple, and green preparation of polyhydroxylated C60, which is water-soluble, 200 mg of pure C60 is added to 20mL 30% H2O2 and sonicated with the sonicator models UP200Ht or UP200St. The sonication parameters were 30% amplitude, 200 W at pulsed mode for 1 h at room temperature. The reaction vessel is placed into a refrigerated circulator water bath in order to maintain the temperature inside the vessel at ambient temperature. Before sonication, C60 is immiscible in aqueous H2O2 and is a colorless heterogeneous mixture, which turns to a light brown color after 30 min of ultrasonication. Subsequently, in the next 30 min of ultrasonication it turns into a completely dark brown dispersion.
Hydroxyl donor: Intense ultrasonically generated (= acoustic) cavitation creates radicals such as cOH, cOOH and cH from H2O and H2O2 molecules. The use of H2O2 in aqueous media is a more efficient approach to introduce –OH groups onto the C60 cage rather than only using H2O for the synthesis of fullerenol. H2O2 plays an important role in the ultrasonic hydroxylation intensification.

Ultrasonic hydroxylation of C60 using dil. H2O2 (30%) is a facile and fast one-step reaction to prepare fullerenol. Requiring only a short time for the reaction, the ultrasonic reaction offers a green and clean approach with a low energy requirement, avoiding the use of any toxic or corrosive reagents for the synthesis, and reducing the number of solvents required for the separation and purification of C60(OH)8∙2H2O.

Ultrasonic processor UP400St (400W) for homogenization, dispersion, emulsification and sonochemical applications.

UP400St (400W, 24kHz) is a powerful ultrasonic disperser

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Ultrasonic Polyhydroxylation Pathway

When intense ultrasound waves are coupled into a liquid, alternating low-pressure / high-pressure cycles create vacuum bubbles in the liquid. The vacuum bubbles grow over several cycles until they cannot absorb more energy, so that they collaps violently. During the bubble collapse extreme physical effects such as high temperature and pressure differentials, shock waves, microjets, turbulences, shear forces, etc. This phenomenon is known as ultrasonic or acoustic cavitation.These intense forces of ultrasonic cavitation decompose the molecules to cOH and cOOH55 radicals.
Afreen et al. (2017) assume that the reaction may progress in two pathways simultaneously. cOH radicals as reactive oxygen species (ROS) attach onto the C60 cage to give fullerenol (Path I), and/or –OH and cOOH radicals attack the electron deficient C60 double bonds in a nucleophilic reaction and this leads to the formation of fullerene epoxide [C60On] as an intermediate in the first stage (Path II) which is similar to the mechanism of the Bingel reaction. Further, the repeated attack of cOH (or cOOH) on C60O via an SN2 reaction results in polyhydroxylated fullerene or fullerenol.
Repeated epoxidation may take place which produces successive epoxide groups e.g., C60O2 and C60O3. These epoxide groups could be possible candidates to generate other intermediates e.g. hydroxylated fullerene epoxide during sonolysis (= sonochemical decomposition). Additionally, the subsequent ring opening of C60(OH)xOy with cOH can result in the formation of fullerenol. The formation of these intermediates during the sonolysis of H2O2 or H2O in the presence of C60 is inevitable, and their presence in the final fullerenol (although in a trace amount) cannot go unnoted. However, because they are only present in trace amounts in the fullerenol they are not expected to cause any significant impact. [Afreen et al., 2017]

High-Performance Sonicators for Fullerene Dispersion

Hielscher Ultrasonics supplies probe-type sonicators for your specific requirements: Whether you want to sonicate small volumes on lab scale or produce large volume stream on industrial scale, the Hielscher portfolio of high-performance sonicators offers the perfect solution for your fullerene dispersion. The high power output, precise adjustability and the reliability of our ultrasonicators make sure that your process requirements are fulfilled. Digital touch screens and automatic data recording of the ultrasonic parameters on an integrated SD card make the operation and control of our ultrasonic devices very user-friendly.
The robustness of Hielscher ultrasonic equipment allows for 24/7 operation at heavy duty and in demanding environments.
The table below gives you an indication of the approximate processing capacity of our ultrasonicators:

Batch Volume Flow Rate Recommended Devices
1 to 500mL 10 to 200mL/min UP100H
10 to 2000mL 20 to 400mL/min UP200Ht, UP400St
0.1 to 20L 0.2 to 4L/min UIP2000hdT
10 to 100L 2 to 10L/min UIP4000hdT
n.a. 10 to 100L/min UIP16000
n.a. larger cluster of UIP16000

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  • Sadia Afreen, Kasturi Muthoosamy, Sivakumar Manickam (2018): Sono-nano chemistry: A new era of synthesising polyhydroxylated carbon nanomaterials with hydroxyl groups and their industrial aspects. Ultrasonics Sonochemistry 2018.
  • Sadia Afreen, Kasturi Muthoosamy, Sivakumar Manickam (2017): Hydration or hydroxylation: direct synthesis of fullerenol from pristine fullerene [C60] via acoustic cavitation in the presence of hydrogen peroxide. RSC Adv., 2017, 7, 31930–31939.
  • Grigory V. Andrievsky, Vadim I. Bruskov, Artem A. Tykhomyrov, Sergey V. Gudkov (2009): Peculiarities of the antioxidant and radioprotective effects of hydrated C60 fullerene nanostuctures in vitro and in vivo. Free Radical Biology & Medicine 47, 2009. 786–793.
  • Mihajlo Gigov, Borivoj Adnađević, Borivoj Adnađević, Jelena D. Jovanovic (2016): Effect of ultrasonic field on isothermal kinetics of fullerene polyhydroxylation. Science of Sintering 2016, 48(2):259-272.
  • Hirotaka Yoshioka, Naoko Yui, Kanaka Yatabe, Hiroto Fujiya, Haruki Musha, Hisateru Niki, Rie Karasawa, Kazuo Yudoh (2016): Polyhydroxylated C60 Fullerenes Prevent Chondrocyte Catabolic Activity at Nanomolar Concentrations in Osteoarthritis. Journal of Osteoarthritis 2016, 1:115.


Facts Worth Knowing

C60 Fullerenes

A C60 fullerene (also known as buckyball or Buckminster fullerene) is a molecule that is built from 60 carbon atoms, arranged as 12 pentagons and 20 hexagons. The shape of a C60 molecule resembles a soccer ball. The C60 fullerens are a non-toxic antioxidant showing a potency 100–1000 higher than vitamin E. Although C60 itself is not water-soluble, many highly water soluble fullerene derivatives such as fullenerol have been synthesized.
C60 fullerens are used as antioxidant and as biopharmaceutical. Other applications include material science, organic photovoltaics (OPV), catalysts, in water purification and biohazard protection, portable power, vehicles and medical devices.

Solubility of pure C60:

  • in water: not soluble
  • in dimethyl sulfoxide (DMSO): not soluble
  • in toluene: soluble
  • in benzene: soluble
Surface structure of c60 fullerenes (Buckminster fullerenes, buckyballs)

Surface structure of C60 fullerenes
source: Yoshioka et al. 2016

Polyhydroxylated C60 / Fullenerols

Fullernerol or fullerols are polyhydroxylated C60 molecules (hydrated C60 fullerene: C60HyFn). The hydrolylation reaction introduces hydroxyl groups (-OH) to the C60 molecule. C60 molecules with over 40 hydroxyl groups have a higher water solubility (>50 mg/mL). These exist as monodisperse nanoparticles in water, and have a valiant polishing effect. They exhibit superior antioxidant and anti-inflammatory properties. Polyhydroxylated fullerenes (fullerenols; C60(OH)n) can be dissolved in some alcohols and then precipiteated in an electrochemical process, creating a nanocarbon film on the anode. Fullerenol films are used as a biocompatible coating, inert to biological objects and can facilitate the integration of non-biological objects into body tissues.
Solubility of Fullenerol:

  • in water: soluble, can reach >50 mg/mL
  • in dimethyl sulfoxide (DMSO): soluble
  • in methanol: slightly soluble
  • in toluene: not soluble
  • in benzene: not soluble

Color: Fullerenol bearing more than 10 –OH groups exhibit a dark brown color. With an increasing number of –OH groups, the color gradually shifts from dark brown to yellow.

Water-soluble, polyhydroxylated C60 can be synthesized using ultrasonics

Solubility of Solubility of C60(OH)8.2H2O in comparison to C60 in different solvents. source: Afreen et al. 2017

Applications and Use of Fullerenols:

  1. Pharmaceutical: Diagnostic reagents, super drugs, cosmetics, nuclear magnetic resonance (NMR) with the developer. DNA affinity, anti-HIV drugs, anti-cancer drugs, chemotherapy drugs, cosmetics additives and scientific research. Compared with the pristine form, polyhydroxylated fullerenes have more potential applications due to their enhanced water solubility. It has been found that fullerols can reduce cardiotoxicity of some drugs and inhibit HIV-protease, hepatitis C virus and abnormal growth of cells. Furthermore, they exhibited excellent free-radical scavenging abilities against reactive oxygen species and radicals under physiological conditions.
  2. Energy: Solar battery, fuel cell, secondary battery.
  3. Industry: Wear resistant material, flame retardant materials, lubricants, polymer additives, high-performance membrane, catalyst, artificial diamond, hard alloy, electric viscous fluid, ink filters, high-performance coatings, fire retardant coatings, manufacturing bioactive materials , memory materials, embedded molecular and other characteristics, composite materials etc.
  4. Information industry: Semiconductor record medium, magnetic materials, printing ink, toner, ink, paper special purposes.
  5. Electronic parts: Superconducting semiconductor, diodes, transistors, inductor.
  6. Optical materials, electronic camera, fluorescence display tube, nonlinear optical materials.
  7. Environment: Gas adsorption, gas storage.

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