Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nanoparticles: Polymer knots with silicon hearts

30.08.2013
Biocompatible complexes for drug delivery applications get a structural boost from nanoscale silicon cages

Protein-based drugs show promising activity against many hard-to-treat targets. Getting these biomolecules past the body’s numerous defenses, however, requires innovative technology such as drug-delivering nanoparticles. Polylactic acid (PLA) is a potential candidate because it is non-toxic, biodegradable, and spontaneously assembles into tiny structures under the right conditions.


Polylactic acid (PLA)-based organic–inorganic polymers (above) self-assemble into nanoparticle spheres with the potential for drug delivery. During polymerization, PLA (magenta) forms one of two mirror-image structures.

Reproduced, with permission, from Ref. 1 © 2012 Royal Society of Chemistry

Chaobin He from the A*STAR Institute of Materials Research and Engineering in Singapore and co-workers have developed a robust method to synthesize PLA nanoparticles using copolymer technology and a rigid ‘nanocage’ made from silicon.

During polymerization, PLA forms into one of two mirror-image compounds, known as L-type or D-type (see image). When chemists mix L- and D-type PLA chains together, their complementary shapes interlock through a process known as stereocomplexation. Recently, chemists have found that constructing PLA chains containing discrete ‘blocks’ of L- and D-compounds brings unprecedented control over nanoparticle formation — allowing them to produce distinct shapes.

Although stereocomplexation improves the mechanical attributes of PLA nanoparticles, many of these compounds aggregate undesirably after a few days in water. He and his team investigated whether they could retain the nanoparticles’ shape using silsequioxane, a stiff and small framework of silicon–oxygen atoms that has a strong record of boosting polymer strength at the molecular level.

After connecting silsequioxane to individual L- and D-type PLA chains, the researchers used a process called atom transfer radical polymerization to generate organic–inorganic hybrid co-polymers with well-defined PLA and silsequioxane segments. When they mixed two block co-polymers with complementary L- and D- PLA segments into polar organic solvents that hold slight electrical charges, the chains self-assembled into nanoscale spheres. Because co-polymers without matching L- and D-segments remained in solution under the same conditions, the team deduced that stereocomplexation is the primary force driving nanoparticle formation.

Experiments revealed that the silicon nanocages significantly improved PLA nanoparticle stability: even after a month in diluted aqueous solution, these hybrid compounds retained their unique shapes. Furthermore, the team found that incorporating longer silsequioxane units into the PLA chains caused the nanoparticles to assemble into smaller spheres. According to He, this suggests that the inorganic constituent can influence the probability of stereocomplexation — findings that open opportunities to precisely tune nanoparticle size and shape.

He and co-workers anticipate that their nanoparticles might enhance the properties of PLA plastics used for medical implants by acting as novel ‘filler’ substances. He explains that the tiny compounds should enhance interfacial adhesion inside large sheets of PLA, thereby augmenting its ductility and toughness.

The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering

Journal information

Tan, B. H., Hussain, H., Leong, Y. W., Lin, T. T., Tjiu, W. W. & He, C. Tuning self-assembly of hybrid PLA-P(MA-POSS) block copolymers in solution via stereocomplexation. Polymer Chemistry 4, 1250–1259 (2013).

A*STAR Research | Research asia research news
Further information:
http://www.research.a-star.edu.sg/research/6723
http://www.researchsea.com

More articles from Materials Sciences:

nachricht Robust and functional – surface finishing by suspension spraying
19.09.2017 | Fraunhofer-Institut für Keramische Technologien und Systeme IKTS

nachricht Graphene and other carbon nanomaterials can replace scarce metals
19.09.2017 | Chalmers University of Technology

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

Im Focus: Silencing bacteria

HZI researchers pave the way for new agents that render hospital pathogens mute

Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Molecular Force Sensors

20.09.2017 | Life Sciences

Producing electricity during flight

20.09.2017 | Power and Electrical Engineering

Tiny lasers from a gallery of whispers

20.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>