Hydrophilization of nonwoven materials

Description
Nonwoven fabrics made of polypropylene are used in baby diapers as separating layers between the skin and the absorbent materials. As these fabrics are very hydrophobic, they do not allow the liquid to pass through sufficiently.

Hydrophilization by plasma or UV treatment quickly loses its effectiveness in an open atmosphere. We finished the nonwoven fabrics with a hydrophilic LbL double layer directly after plasma etching, which led to permanent hydrophilization with extremely low contact angles.

The degree of hydrophilization could be varied widely depending on the polyelectrolytes used.

Partner

• Procter & Gamble, Cincinnati, OH, USA

Hydrophilization of poorly water-soluble medications

Description
Due to their hydrophobic properties, aqueous suspensions tend to aggregate quickly. We have therefore developed an easily scalable one-step process for hydrophilization of the drug crystals, which allows long-term stable storage of an aqueous formulation without the addition of surfactants.

Fight against the leaf miner

Description
Although pheromones are known to damage the chestnut leaf miner, it is not yet possible to use them for control, as they are quickly degraded and the moths' nuptial flight takes up to 3 days.

Therefore, particles should be developed that carry a toxin inside, pheromones in the capsule shell and an appetizing substance on the surface. We encapsulated 3 µm silica particles with synthetic or biocompatible, fluorescence-labelled LbL layers, provided them with the appetite-stimulating substance and placed them on glass filter papers.

After the moths had eaten the particles, their feces were collected and examined using confocal laser scanning microscopy. Biocompatible LbL layers were digested and the pure silica particles were excreted. Toxins introduced into the coating can thus be effectively eliminated.

Quite unexpectedly, particles coated with synthetic polyelectrolytes were no longer excreted. With sufficiently high particle uptake, flight behavior and thus reproduction can be impaired without pesticides.

Temperature, pH and oxygen sensors

Description
The company Colibri GmbH (Germany) has a special analysis device on the market that can measure the oxygen concentration over the decay time of the emission of platinum complexes with spatial resolution in cell cultivation.

This is very important for assessing cell activity. We have developed sensor particles in the size range from 50 µm to 300 nm with increased light emission. The latter are absorbed by cells so that the oxygen concentration can even be measured inside a living cell.

Similar sensor particles have also been developed for temperature measurements, e.g. on the membranes of fuel cells, in technical fluidic reactors or in PCR devices.

Particles with a size of 1 to 10 µm as well as porous glass molded bodies were also developed for the analysis of pH values. Using 9 µm particles, for example, we were able to resolve the pH gradient between the hair root and hairline for the first time using measurement technology. This allows us to make statements about the pH in the hair follicle.

Partner

• Charité – Universitätsmedizin Berlin, Berlin, Germany
• Institute for Fluid Mechanics and Aerodynamics, Bundeswehr University Munich, Neubiberg, Germany
• Fraunhofer IZI-BB, Potsdam, Germany
• Colibri Photonics GmbH, Potsdam, Germany

Reference

• J. Massing, D. Kaden, C. J. Kähler and C. Cierpka, Luminescent two-color tracer particles for simultaneous velocity and temperature measurements in microfluidics, Meas. Sci. Technol. 27 (2016) 115301 doi:10.1088/0957-0233/27/11/115301
• D. Kaden, L. Dähne, F. Knorr, H. Richter, J. Lademann, M. C. Meinke, A. Patzelt, M. E. Darvin, S. Jung, Determination of the pH Gradient in Hair Follicles of Human Volunteers Using pH-Sensitive Melamine Formaldehyde-Pyranine Nile Blue Microparticles, Sensors 2020, 20(18), 5243; doi:10.3390/s20185243

Functionalization of gas chromatography capillaries for the accumulation of beer aromas

Description
In breweries, the analysis of aromas is of great importance for quality and is still assessed today by tasting, as many aromas, especially of hops, are present in too low a concentration for analysis.

Heatable capillaries are used in gas chromatography for the chromatographic separation of aromas. We provided these with functionalized nanolayers on the inside, which bind specific aromas intermediately and concentrate them.

At higher temperatures, they were released again and could be detected quantitatively despite their very low concentration.

Partner

• Versuchs- und Lehranstalt für Brauerei VLB e.V., Berlin, Germany

Fluorescence standards

Description
Photostable standards in various designs (plates, particles, etc.) are required for the calibration of optical readout devices for various technologies. We have developed extra light-stable fluorescent and phosphorescent dyes for this purpose and incorporated them into corresponding polymer matrices in various forms.

Partner

• QIAGEN GmbH, Hilden, Germany
• ChemBio Diagnostic GmbH, Berlin, Germany

Superhydrophobic coatings of silicone wafers with pores to prevent the passage of aqueous liquids

Description
Silicone membranes with pores in the micrometer range can be used to transmit sound waves or gases. For some applications, these pores must be impermeable to aqueous solutions, such as in smartphones or electronic cigarettes.

For this purpose, we have developed superhydrophobic, nanometer-thin coatings with contact angles of up to 175°, which completely prevent the passage of liquids.

Partner

• Hauni Maschinenbau GmbH, Hamburg, Germany
• SmartMembranes GmbH, Halle (Saale), Germany

Encapsulation and delayed release of nisin for the treatment of cheese against listeria

Description
To prevent the infestation of cheese with dangerous listeria, the rind is treated with the antibiotic peptide nisin.

However, nisin is broken down relatively quickly by bacteria, so the protection does not last long.

In the project, nisin was encapsulated in porous silica particles with semi-permeable LbL layers in order to protect it from attack by bacterial enzymes on the one hand and to achieve a controlled release on the other.

Partner

• Käserei Heinrich Birkenstock GmbH, Hüttenberg, Germany

Reference

• Maik Szendy, Florian Westhäuser, Barbara Baude, Jessica Reim, Lars Dähne, Matthias Noll: „Controlled release of Nisin from Neusilin particles to enhance food safety of sour curd cheese”, J. Food Sci Technology (2019) 56, 1613-1621

Synthesis of labeled special polymers

Description
Acrylamides were copolymerized in graduated ratios with quaternary polyamines and the dye Cy3 with acrylic functionalization.

Due to the very different reactivities of the ternary monomer mixture, specific reaction conditions with defined slow addition of the more reactive monomer were developed.

The composition and molecular weight were analyzed and optimized

Partner

• Unilever United States, Inc.,Englewood Cliffs, NJ, USA