RADBOUD UNIVERSITY NIJMEGEN

RESEARCH PROPOSAL

HONOURS ACADEMY FNWI

The molecular monorail

Authors:Robert BECKER

Nadia ERKAMP

Marieke GLAZENBURG

Evert-Jan HEKKELMAN

Lisanne SELLIES

Supervisor:Prof. Thomas BOLTJE

May 2017

Contents

1 Details 21.1 Applicants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2 Supervisor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3 Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.4 Field of research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Summaries 32.1 Scientific summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2 Public summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 Samenvatting voor algemeen publiek . . . . . . . . . . . . . . . . . . . . 3

3 Introduction 5

4 Background 84.1 The Feringa motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84.2 The ring molecule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.3 Threading of the track . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114.4 The track polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5 Methods 145.1 Optical trapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145.2 Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155.3 Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

5.3.1 Ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165.3.2 Track . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

6 Future applications 186.1 Further shrink down lab-on-a-chip approach . . . . . . . . . . . . . . . 186.2 Lab-on-a-chip approach in health care: Point-of-care testing (POCT) . 18

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1 Details

1.1 Applicants

Robert Becker - BiologyNadia Erkamp - ChemistryMarieke Glazenburg - Physics

Evert-Jan Hekkelman - Physics &MathematicsLisanne Sellies - Chemistry

1.2 Supervisor

Name: Thomas BoltjeTelephone: 024-3652331Email: t.boltje@science.ru.nlInstitute: Synthetic Organic Chemistry RadboudUniversity Nijmegen

1.3 Keywords

Nanomachine, Feringa, polymer, porphyrin, FRET

1.4 Field of research

NWO division: Chemical Sciences [CW]

Code Main field of research13.20.00 Macromolecular chemistry, polymer chemistry

Other fields of research13.30.00 Organic chemistry13.50.00 Physical chemistry12.20.00 Nanophysics/technology14.80.00 Nanotechnology

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2 Summaries

2.1 Scientific summary

In this proposal we present the design for a new kind of nanomachine. A nanoma-chine is an assembly of a distinct number of molecular components that are designedto perform machinelike movements as a result of an appropriate external stimula-tion. The currently existing nanomachines have at least one of the following disad-vantages: they are either slow, non-autonomous or move in an unpredictable direc-tion. Some even suffer from a combination of these. In our design we couple anautonomous motor to a ring that moves along a track.The motor of the Nobel Prize winner Feringa is used to make the nanomachine move.A ring-shaped molecule will be designed and the motor of Feringa will be bound to itin such a manner that it produces a propulsive force. Furthermore, the ring consistsof two porphyrin rings and some bulky groups to prevent it from collapsing or fold-ing. The ring can move along a track made of alternating benzene rings and triplebonds, containing some fluorescent BODIPY groups. A BODIPY group is also presenton the ring, opening up the possibility for FRET as detection method.In the future, the proposed nanomachine may be used for the active transport ofcargo. This in turn may boost the development of a microfluidic lab-on-a chip sys-tem, where it would be used to transfer molecules from one fluid stream to another.Some microfluidic lab-on-a chip systems find application in health care.

2.2 Public summary

Imagine an everyday utensil like a car or a switch and make it a billion times smaller:you now have a nanomachine. In the past years, there has been impressive processin the development of these tiny molecular devices, among which, perhaps the mostappealing to the imagination, an actual four-wheel drive nanocar. Current molecularmachines however still struggle with basic issues like speed and controllability. Thisresearch proposes the design of a new nanomachine to solve exactly these issues: amolecular ‘monorail’ consisting of a ring, driven by rotating propellers, sliding alonga track in one direction. In the future, this design may be useful in medical applica-tions, e.g. the transport of substances in miniature laboratoria.

2.3 Samenvatting voor algemeen publiek

Neem een alledaags gebruiksvoorwerp zoals een auto of een schakelaar en maak diteen miljard keer kleiner: dit is het terrein van de nanomachines. De laatste jarenis er een indrukwekkende vooruitgang zichtbaar in de ontwikkeling van deze minis-cule moleculaire apparaatjes, met als meest tot de verbeelding sprekende doorbraak

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het nano-autootje van de Groningse Ben Feringa. Toch hebben huidige moleculairemachines nog vaak problemen met onder andere snelheid en bestuurbaarheid. Ditonderzoek stelt het ontwerp voor van een nieuwe nanomachine die deze proble-men oplost: een ‘moleculaire monorail’, bestaande uit een ring, aangedreven doordraaiende propellers, die in één richting over een spoor glijdt. In de toekomst zou ditontwerp toepassingen kunnen vinden in de medische wereld, bijvoorbeeld voor hettransporteren van stoffen in miniatuur laboratoria.

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3 Introduction

In 2016, the Nobel Prize in chemistry was awarded to three independently operat-ing researchers, Jean-Pierre Sauvage, Sir J. Fraser Stoddart and Bernard L. Feringa [1].Each of them made a contribution to a relatively new area of research that has anenormous potential: the development of molecular motors.A molecular motor can be briefly defined as “an assembly of a distinct number ofmolecular components that are designed to perform machinelike movements (out-put) as a result of an appropriate external stimulation (input)” [2]. The Nobel Prizewinner Feringa designed and built such a device: a molecular propeller. This moleculeconsists of a rigid stator, an axle and a rotor blade. When exposed to UV light, the ro-tor will perform consistent and unidirectional rotational movement [3]. Combiningfour of these motors led to perhaps even his biggest achievement: his design of a‘nanocar’, illustrated in figure 1 [4].

Figure 1: Operation of Feringa’s nanocar [4]

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One can clearly see the similarities withregular sized cars; Feringa’s nanocar isessentially just a very basic downscale ofthe macroscopic world. Section 4.1 lateron in this proposal will pay elaborate at-tention to his work.Aside from Feringa’s motor, variousother kinds of molecular motors havebeen developed over the years. An ex-ample of this the recent development ofautonomously movingmicroparticles [5]. These particles,or stomatocytes, were able to movethrough a liquid due to a reaction withhydrogen peroxide, catalysed by theplatinum they were loaded with. Theoxygen bubbles produced in the processdeliver the propulsive force. The stoma-tocytes are capable of reaching relativelyhigh velocities. However, they moverather randomly through the fluid.Motors that do have this directionalityare synthetic walkers, DNA walkers forexample. DNA walkers are made en-tirely of DNA and consist of little morethan two legs propagating along a DNAtrack by hybridization with DNA fuel strands [6]. This ensures the directional move-

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ment, but the walkers are often extremely slow in their progress. Furthermore, mostDNA walkers require periodic addition of fuel strands, whereas a more autonomousapproach (i.e. no need for active chemical fuel addition) would be preferable.

The proposed research is aimed at finding solutions to exactly the three issues il-lustrated by the examples above: directionality, speed and autonomy. To achievethis, existing elements will be combined and improved, inspired by the achievementsmentioned in the section above. Together this will form an attempt at solving the im-portant challenges in the area mentioned above and coming a step closer to fullyfunctioning, autonomous nanomachines.

Figure 2: Spatial impression of the proposed nanomachine. The motor molecules are indicatedin green, the ring in blue, the track in purple, the bulky groups by the black circles and thefluorescent BODIPY groups by the red circles.

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All of the above led to the following research question:

How to build an autonomous and unidirectional nanomachine witha high speed?

A sketch of the proposed design is illustrated in figure 2. In this design, the motormolecules (green) are incorporated in a ring (blue) that will be threaded onto a track(purple polymer), allowing it to move in only one dimension. Propulsion by the mo-tor molecules will yield the desired speed and autonomy.

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4 Background

4.1 The Feringa motor

No nanomachine is complete without a means of doing work, and Feringa’s motor isone of the most effective ways to achieve work in a rotational fashion. Its spectacularproperties and successful track record has made this the motor of choice in this pro-posal.The motor consists of a so-called ‘stator’ and a ‘rotor’, connected by a double car-bon bond. While different versions do exist, they all operate in the same manner(see figure 3). An absorbed photon causes a cis-trans isomerization in the rotor, af-ter which the molecule finds itself in an unstable form. The motor reaches a stableform by thermal helix inversion, which results in a 180◦ rotation. When another pho-ton hits the molecule, this process repeats itself. That way the motor keeps rotatingin the same direction when illuminated constantly [7] [8]. The motion can only beperformed in one direction because the chiral carbon atom at the back of the rotordictates which way the rotor turns if a photon is absorbed. Changing this atom’s chi-rality will cause the motor to turn the other way around. [10]

Figure 3: All steps in the process of turning on which the Feringa motor is based.

The difference between various versions of this particular machine is the structure ofthe stator. A conformational change in the stator greatly influences the rate at whichthe thermal helix inversion takes place, researched in depth by the Feringa group [9]They found that a certain version of Feringa’s motor can achieve a rotational speed of3 MHz [9]. This version is depicted in figure 4, including how the attachment to thering will look.

Not only is this motor molecule fast, reliable and still quite small, the only sourceof energy it needs to move is light. Specifically, any light with a wavelength larger

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Figure 4: Structure of the used Feringa motor, including how the motor will be attached to thering.

than 280 nm suffices [11]. This means the solution will not be polluted by any fuel,catalysts or possible waste products.

The use of Feringa’s molecule as a propeller instead of as a wheel has so far not beenexplored. Because the motor turns so often every second, even the slightest bladepitch should result in a force parallel to its rotational axis. We intend to use this forceto propel our machine forwards. If this project is realised, it will be the first time apropeller is used for directional movement on a nanoscale.

4.2 The ring molecule

Designing a specific new ring allowed for correct placement of the motor. The ‘stator’of the motor is incorporated in the designed ring, as illustrated in figure 5. Incorpora-tion of the stator as a structural element has been examined before in for example afourwheeled nanocar [4]. However, it has never been studied in a ring before. Incor-poration of the stator may help to place the motor at the correct angle with respectto the direction of movement for efficient movement. For this the bond between thestator and rotor should be in the direction along the track. Estimating which angle isreached for the current design of the nanomachine poses a challenge. When exper-imentally is determined that the direction of the stator causes inefficient movementthe bond between the stator and benzene connected to the porphyrin can be sub-stituted. Furthermore, rotation about the connection between the porphyrins andmotor may be possible, through which the motor ends up in the interior of the ring.This problem can also be solved by using another more rigid connection. A very im-portant aspect of the design of the ring is the diameter. This has been chosen to fitthe width of the track. Besides the motors, porphyrins have been placed to form thering. These groups are multifunctional for the complex. Firstly, they increase therigidity of the ring, ensuring the ring does not collapse before being placed on the

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Figure 5: Design of the ring molecule with incorporated Feringa motors (green), porphyrinrings (blue), bulky groups (black) and a BODIPY molecule (red).

track. Furthermore, they enhance the hydrophobicity of the complex. In combina-tion with a hydrophobic track and a hydrophilic solution this may lead to an energet-ically favourable threading reaction. This effect will later be further discussed. Lastly,porphyrins give rise to multiple applications for our nanomachine. A metal ion canbe placed in the porphyrins. In addition of the bonds to the porphyrin an extra bondcould be formed depending on the oxidation state of the ion and the ion that is cho-sen. Increasing the oxidation state may allow attachment and decreasing it may allowfor detachment of an extra group. This effect has widely been examined within thefield of porphyrin chemistry [12].

A risk in the placement of the porphyrins in the ring is that the porphyrins mightrotate to align with the aromatic groups in the track. This alignment could be en-ergetically favourable by π-π-stacking or increased hydrophobic interactions [13].An increase of resistance could decrease the speed of the nanomachine. To preventrotation of the porphyrin, bulky groups have been placed to form a roof over theporphyrin. To be able to detect the speed of the nanomachine one of these groups

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has been chosen to be the fluorescent group BODIPY (boron-dipyrromethene). Theother groups have been chosen to be similar groups to prevent major disturbanceof the symmetry of the system. For future applications, other functional groups canalso be attached at this side.

The designed ring has never been built before. Very little is known from literatureabout placing the motor under the correct angle, ensuring the width of the ring is suf-ficient for the track and the treading and making rotation of the porphyrins unattrac-tive. These subjects, although thoroughly examined with computer models as well asscale models, will be among the greatest challenges of this research.

4.3 Threading of the track

One essential step in the process of creating this nanomachine is the so-called thread-ing of the ring onto our chosen track. A lot of research has been done on the manyaspects of this process in general, and it is a phenomenon that is used extensively.[14][15] [16] [17] However, it is difficult to say beforehand if the threading in this particu-lar case will go smoothly by itself. In general, it is not necessary for the ring and poly-mer to have any special interactions, since purely statistically threading may happento some of the rings [18]. This can be improved by hydrophobic/hydrophilic interac-tions. The ring that needs to be threaded in this proposal has a hydrophobic interior.If the solution consists mainly of water or other hydrophilic substances, this may in-fluence the threading rate positively given that the used track is hydrophobic as well[19]. We propose to measure if the threading rates in water are acceptable as is forcontinuation of the study. There is a possibility that the track and ring will aggregatein a hydrophilic solution. A way to solve this problem, if it rears its head, can be tomake the bulky groups mentioned in the section above hydrophilic. This way thering will be soluble in water.If these ‘natural’ rates are deemed too low, several steps can be taken to improvethis. Changing the solution from H2O to MeCN or acetone can change the threadingconstants, for better or for worse [20] [14]. In the case that even more measures haveto be taken, it is possible to look into increasing the attraction between track and ring.This could be achieved involving electrostatic forces by, for example, making surethe ring has a negative charge while giving, preferentially the ends of the polymer,positive charges. While possible, it has to be checked if the machine’s force is largeenough to overcome this bound state. These charges could encourage the rings tofind the threading locations. If the whole polymer is charged, the risk exists that therings will simply stick to the polymer without threading, however this can be triedas well if the motors get stuck on the charges at the ends of the polymer [20]. Sincethreading is a common occurrence in papers on chemistry, we have full confidencethat any problems can be handled swiftly.

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4.4 The track polymer

There are a number of requirements the track has to fulfil. Firstly, the polarity of thetrack should match the polarity of the interior of the ring. This way the probabilityof threading is increased. Because the interior of the ring is hydrophobic the trackshould also be hydrophobic. Secondly, to detect if the ring moves along the track,fluorescent groups need to be incorporated into the track. If the fluorescent groupsand the track differ in polarity, the ring may stick onto the fluorescent groups. Con-sequently, the body of the track should be similar to the fluorescent groups. Thirdly,by using a relatively linear track, coiling of the track will be reduced. The track willconsist of benzene groups with alternating triple bonds and BODIPY groups. Thecombination of BODIPY groups with triple bonds gives rise to a red coloured trackwhen illuminated by light [21]. This opens up the possibility to use FRET for detec-tion. This method is based on the interaction between BODIPYs on the track and thering. To prevent interaction of BODIPYs with each other within the track, the BOD-IPY molecules need to be placed at a certain distance. BODIPY has a Förster radiusof 57 Å, which is the distance at which energy transfer in FRET is 50% efficient [21].Because the efficiency decreases with 1/1+ ( R

R0)6) [22], doubling the distance makes

the efficiency decrease to 1.5%, Translating this distance to the length of atoms in thetrack, 1 in 22 benzene rings can be replaced with BODIPY groups to generate a flu-orescent track. For measuring the speed of the ring sliding along the track, a lineartrack is required. To generate a linear track optical trapping of beads at the end of thetrack is used (see section 5.1). These polystyrene beads are placed onto the track afterthe threading of the ring. The complete design of the track with the optical beads isillustrated in figure 6. In polar solvents the track may form aggregates. If this problemis encountered, bulky groups can be incorporated into the design of the track. Thesebulky groups should not be too large, because they must fit in the interior of the ring.

Figure 6: Structure of the track with alternating benzene and triple bonds and with 1 in 22benzene rings substituted with a BODIPY group.

The length of the track depends on the observed speed of the nanomachine and themaximum length of the track that can be synthesized. These can be experimentallydetermined, after which the track of the correct size can be synthesized. The length

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of the track can be influenced by the amount of starting product or addition of ter-mination groups.

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5 Methods

5.1 Optical trapping

For the motor to slide over the track it is obviously necessary for the polymers to beas rigid and stationary as possible. We can take preventive measures to make surethis becomes a reality. It would be easiest if one was able to pick up both ends of apolymer and just stretch it out. In fact, this is done quite often already by a techniquecalled ‘optical trapping’. The only thing needed to use it are two beads attached tothe ends of the polymer.

Figure 7: Optical trapping, visualized by two light beams that create a force (FA) which movesthe bead.

A highly focused laser beam set up like in figure 7 creates a three-dimensional trapfor the polystyrene beads. Since light carries momentum, and the refractive indexof the beads result in a change of the direction of this momentum, the beads willexperience a transfer of momentum from the light to the beads. By making sure theintensity of the laser is highest in the middle of the beam and lowest at the edges, aswell as focusing the laser with a convex lens, the beads will always experience a forcein the direction of the lasers’ focal point [23]. This effect can be seen more clearlyin figure 7 [23]. Moving the light beam makes the trapped beads move as well. Thisway the polymer can be stretched to the point that it resembles a reasonably straight

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thread. The use of this effect is common in DNA and protein research, so we can beconfident in its effectivity (For example, in a paper by B. Jagannathan et al. [24] oreven in combination with fluorescence microscopy done by G.A. King et al. [25]).

5.2 Detection

After synthesizing the molecule and incorporating the track, the next major step isto detect and verify the behaviour of the system. The movement of the motor alongthe track cannot easily be identified using regular optical microscopic techniques,because the scale of the molecules is beneath the diffraction limit of visible light.This means other methods of molecular detection need to be addressed.

Different detection methods were considered to evaluate if the nanomachine is placedcorrectly on the track and to determine its speed. The latter is important to rule outthe possibility that the motion of the motor is only Brownian motion. For this, a ref-erence experiment is performed during which Feringa’s motors are not shined uponwith light of the correct wavelength.

To test if the motor is placed correctly on the track and is not hanging against the side,NMR is used. If this effect occurs, hydrophilic groups can be attached to the outsideof the ring to prevent this. To determine what the speed of the motor is AFM and STMwere considered initially. However, both these methods require the fixation of theobject on a surface. This might heavily influence the movement of the nanomachineand is not suitable for that reason. A more convenient way is the usage of fluorescentgroups to identify the track and the nanomachine. As discussed earlier, both the trackand the ring molecule will be equipped with a fluorescent BODIPY group. This setupenables the application of a detection method based on a phenomena called Försterresonance energy transfer (FRET).

Using FRET, one can achieve measurements of proximity on molecular length scales[26] not available through any other method [27]. The donor fluorophore on the trackcan be excited by using light. Hereby energy is transferred via induced dipole-dipoleinteraction to the acceptor on the ring. As mentioned before, the efficiency of thetransfer is inversely proportional to the sixth power of the distance between the twochromophores [26]. This means FRET has an approximate resolution of 1 to 10 nm,which is sufficient to track the movement of the motor. BODIPY is known to havethis specific interaction with itself [21], meaning it will be used both as the donorand the acceptor fluorophore. In this case, FRET can be detected by the resultingfluorescence depolarization, which has successfully been achieved in the past [28].

The idea is to let the nanomachine move freely along the track. As the fluorophorescome close to each other, it will be visible through the detection of FRET. Several

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successive detections indicate the desired movement of the ring along the polymer.For the distance between the BODIPY groups is known, this yields rather detailedinformation about the molecule movement.

5.3 Synthesis

5.3.1 Ring

The ring is built up of several components, see figure 8.

Figure 8: Retrosynthetical scheme for the synthesis of the ring.

These components are synthesized with side groups that can be used for assemblyof the ring. Using pinacolatoboron (Bpin) groups on one component and bromineatoms on the other, a Suzuki reaction can be used to couple the components. Inthis way similar rings are assembled [38]. Bis(pinacolato)diboron adds to alkenes

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[29], therefore first 2-ethenyl groups are connected to the motor. Starting off withFeringa’s motor, firstly the stator is synthesized with 2-ethenyl groups [30] [31] [32].Secondly in two successive reactions [33] the rotor is modified such that it can easilybe placed onto the stator. Then the stator and rotor are combined and the doublebond between these components is formed [33]. The synthesis of this motor hasbeen researched extensively in the past. The only difference is the attachment of the2-ethenyl side groups. To finish the motor the 2-ethenyl groups are replaced by Bpingroups [37].

Then the ring is formed following previous research [38] with some adjustments.Firstly, the bromine atom is shifted one place, to prevent the bulky groups from ro-tating into the interior of the ring. Secondly, iodine atoms are included in the design,to create a way to connect bulky and fluorescent groups to the porphyrin ring [34].Zinc atoms are added to the porphyrins to occupy the free centre in the middle [35].These zinc atoms can easily be removed at the end and prevent other metals requiredfor the coupling reactions from entering the porphyrin rings [36]. Then to half of theporphyrin rings a bulky and a fluorescent group are coupled and to the other halfonly bulky groups are coupled.

Finally, the porphyrin rings (one with and one without a fluorescent group) are cou-pled with the motor by using a Suzuki reaction to form the ring [38].

5.3.2 Track

The first step in the synthesis of the track is the synthesis of the polymers betweenthe BODIPY’s (appendix 1) [39]. Shorter versions of this polymer have already beensynthesised [39]. Hypothesized is that by mixing the starting compounds in a deter-mined ratio the average length can be altered. The desired ratio will be determinedexperimentally since the reaction constants of the multiple reactions are unknown.The polymers with the average length of 21 repetitive units will be obtained by theuse of column chromatography. If separating the fractions turns out to be difficultthese polymers can be synthesized bottum-up to only have a specific length. Next,the BODIPY groups are synthesised [40]. This can be performed according to liter-ature except for the addition of extra side groups, which are hypothesized to havelittle effect on the synthesis. The obtained polymers and BODIPY groups are mixedin 1:1 ratio to form the track [39] [40]. When no significant amount of lengtheningoccurs an excess of polymers is added to the mixture to secure the terminal groupof the track is the terminal triple bond of the polymer and not the BODIPY. After thethreading has taken place polystyrene beads can be attached to the terminals of thetrack by a click reaction [41].

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6 Future applications

6.1 Further shrink down lab-on-a-chip approach

The nanomachine suggested in this proposal could be a possible tool to further down-scale the volumes of the microfluidic lab-on-a-chip approach. The term lab-on-a-chip describes the approach to conduct chemical reactions in volumes 5-9 timessmaller than in conventional laboratories [42]. To process a reaction of two or moresubstances that are initially present in two different fluid streams, first the substancesneed to get in contact with each other [42].At very small fluid volumes however, flow of the fluid streams is no longer tubular butlaminar [42]. A laminar fluent stream can be regarded as a big stream consisting ofseveral different parallel small streams. In contrast to tubular streams, mixing takesplace only via diffusion [42]. Considering that diffusion only occurs if there is an in-terface present between the two streams, the necessity of mixing becomes obvious.As already mentioned a metal ion can be placed in the porphyrins. Depending on theoxidation state of the metal an additional group could be bound. Changing the oxi-dation state could allow attachment and detachment of this extra group. This effecthas been described within the field of porphyrin chemistry. [43]. The usage of thenanomachine as carrier of single molecules could make it possible to circumvent theobstacle of mixing two fluid streams before a reaction between two substances canoccur. By using nanomachines as carrier, it might be possible to reduce the amountof substrate within the microfluidic system. Theoretically the amount of productcould be regulated by varying the amount of substrates carried by the nanomachine.However, to use the nanomachine for such a purpose, the ends of the polymer wouldhave to be fixated in the separated fluids.

6.2 Lab-on-a-chip approach in health care: Point-of-care testing(POCT)

The microfluidic lab-on-a-chip approach is of growing importance in health-care.Point-of-care testing devices provide both trained and untrained staff with diagnos-tic results at the patient room [44]. The most obvious advantage of POCT is that itis much faster than conventional laboratory analysis of specimens [45]. One of themost established microfluidic lab-on-a-chip devices is a glucose meter to monitorthe glucose concentration in blood of patients. The glucose measuring is based onenzymatically reactions. The reactions in such devices are conducted with glucose-1-dehydrogenase (GDH) which has lower accuracy than other enzymes [45]. Maybe,the nanomachine suggested in this proposal could transport essential co-factors,such as NAD, which are necessary for GDH to work as a catalyst. In that way thewhole process of the glucose measurement could be regulated more exactly. How-

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ever, as mentioned above, first of all one would have to succeed in fixing the ends ofthe polymer in separate sections on the chip, without impairing the function of thenanomachine.

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Appendices

Synthesis of the track

Synthesis of the polymer and BODIPY

25

Coupling the polymer and BODIPY

26

Coupling polystyrene beads to the track

27

Synthesis of the ring

Synthesis of the motor

28

Synthesis of the components of the ring

29

Synthesis of the phorphyrin ring with BODIPY

30

Synthesis of the phorphyrin ring without BODIPY

31

Coupling the motor and the porphyrin rings

32

Removal of the Zn

33