1. Safeguarding food quality using immobilized nano-compartments as active packaging systems
Svetlana Stolarov, Ionel Adrian Dinu,
Wolfgang Meier and Cornelia Palivan
Department of Chemistry, University of Basel
Madrid, Spain 10 –

2. Food packaging Active packaging: Smart/intelligent packaging:
Prolonging shelf-life of the food
Protecting food from environmental influences
Smart/intelligent packaging:
Sense and inform the condition of product
Sensors for monitoring of food quality and safety:
pH of 6.8
Low pH
raw milk > biosensors.
carrot juice > release of antioxidants to maintain food quality.
Vitamin C
B.Kuswandi et al. Sens.& Instrumen.Food Qual. 2011

3. Safeguarding of food quality using “functional” containers
Polymer
nano-compartment
Membrane proteins, biopores
Antioxidant compounds
Proteins, enzymes, mimics

4. Polymer nano-compartments
Poly-2-methyl-2-oxazoline
Polydimethylsiloxane
Hydrophilic block
Hydrophilic block
Hydrophobic block
Mw = 6000 – g/mol
Possibility of end groups functionalization (biotin, fluorescent dyes, antibodies)
Non-toxic (biocompatible blocks)
Various architectures (vesicles, micelles, tubes)
Polymer membrane with tuneable properties (permeability, mechanical properties)
High stability
Was sind amphiphilic Blockcopolymere?
Diese sind lange kettenförmige Moleküle, die aus einem wasserlöslichen und einem wasserunlöslichen Block aufgebaut sind, die kovalent miteinander verknüpft sind.
In wässriger Lösung verhalten sie sich wie höhermolekulare Homologe von Detergenten und bilden selbstorganisierte Ueberstruckturen wie Mizellen, Vesikel, oder Nanoröhrchen.
Polymersome (vesicle) formed from PMOXAmPDMSnPMOXAm
O. Onaca, et al, Macromol.Biosci, 2010, 10(5), 531..

5. Smart surfaces:
Insertion of a protein gates (biopores) in polymer membrane (OmpF, gramicidin)
Encapsulation of a dye, enzyme and/or vitamin C:
Superoxide dismutase (SOD) or dye
(detoxification of and opening of the protein gate)
Dye as a sensor
Vitamin C: as antioxidant
Advantages:
Encapsulation of a pH-sensitive dye to obtain a sensor for detection of decline in food freshness.
Long-term immobilization of nano-scaled containers on solid support (food package).
pH-triggered release of encapsulated antioxidant.

6. Long-term stable immobilization of nano-containers on glass surface
Oxidation of hydroxyl-end groups to aldehyde groups
Functionalized containers
HO-PMOXA6-PDMS44-PMOXA6-OH
OHC-PMOXA6-PDMS44-PMOXA6-CHO
Dess-Martin-Periodinane
200 nm
200 n
Self-assembly of copolymer in PBS before (A) and
After (B) modification (TEM) A B

7. Synthesis of the linker:
Immobilization of nano-containers on glass surface
Synthesis of the linker:
ACN, RT
24h
Surface functionalization:

8. Functionalization of glass surface
Contact angle
Surface
H2O contact angle(°)
glass
38.3
functionalized glass
52.7
AFM :
Glass surface:
Functionalized glass surface:

9. Immobilization of nano-containers on glass surface
- aldehyde
AFM :
Immobilized nano-containers

10. Immobilization of nano-containers on glass surface
AFM image of immobilized nano-scaled containers:
Profile:
200 nm
Topography

11. Stability of immobilized nano-containers on surface under dry conditions
2 weeks after immobilization
10 weeks after immobilization
Topography:
11 months after immobilization
Profile:

12. Conclusions
The modification of hydroxyl-end groups of copolymer to aldehyde was successful
The synthesis of the linker was performed and used for functionalization of glass surface.
Nano-containers are stable on glass surface under dry conditions (nearly years)

13. Outlook
Immobilization of nano-compartments containing model small molecules (dyes or antioxidants) on a glass surface
Investigate the stability of smart surfaces with dye/antioxidant-loaded nano-containers
Study of encapsulation and release of various antioxidants
Immobilization on other surfaces (PET, LDPE) used in food packaging

14. Thank you for attention!