S1: Preparation of magnetic modified particles (MPs)
Preparation of graphite oxide
Graphite (2 g), NaNO
3
(1 g) and KMnO
4
(6 g) were added with stirring to concentrated
H
2
SO
4
(46 ml) placed in ice bath. The mixture was stirred overnight with gradual temperature growth. Water (400 ml) was slowly added and the mixture was heated at 90 ºC for 2 h. After that, H
2
O
2
(3 %) was slowly added as long as colour turned to yellow. Product was separated, washed several times with water and dried at 40 ºC.
Preparation of graphene (GR)
Hydrazine (4 ml, 35 %) and NH
3
(32 ml, 25 %) were added with stirring to the suspension of
GO in 300 ml of water. The mixture was heated on a water bath for 1 h and after cooling the mixture was washed several times with water and dried at 40 ºC.
Preparation of maghemite nanoparticles (MPs γ-Fe
2
O
3
)
1 g of FeCl
3
•6H
2
O was dissolved in 80 ml of MilliQ water and a solution of 0.2 g of NaBH
4 in ammonia (3.5%, 10 ml) was poured into the first solution with vigorous stirring. The evolution of hydrogen was observed and mixture turned dark. The obtained solution was heated at boiling temperature for 2 h. After cooling and standing for 12 h at room temperature, the obtained magnetic nanoparticles were separated by external magnetic field, washed several times with water and dried at 40 ºC.
Graphene (GR) modified MPs
The nanoparticles, prepared as described above, were suspended in 80 ml of water and 0.1 g of graphene was added. The mixture was shaken on Biosan OS-10 for 2 h at room
1

temperature and after that separated by external magnetic field and washed several times with water. Product was dried at 40 ºC.
Hyaluronic acid (HA) modified MPs
Suspension of maghemite nanoparticles in 80 ml of water were treated with 1 ml of hyaluronic acid solution (HA) 20 g.L
-1
in MiliQ water. The mixture was shaken for 2 h at room temperature, separated and washed several times with water. Product was dried at 40 ºC.
Gold (GO) modified MPs
Maghemite nanoparticles prepared from 1.5 g Fe(NO
3
)
3
•9H
2
O, as a source of iron, were suspended in 80 ml of water and polyvinylpyrrolidone PVP (1.5 g in 20 ml of water) was added with stirring. After 3 h of stirring a solution of HAuCl
4
(25 ml, 1 mM) was added. The solution was stirred for 1 h and a solution of trisodium citrate dihydrate (750 µl, 26.5 mg. ml -
1
) was added. The solution was stirred overnight, separated by magnet, washed with water and dried at 40 ºC.
Glucose (GL) modified MPs
Suspension of maghemite nanoparticles in 80 ml of water were treated with glucose (1 g). The mixture was shaken for 6 h at room temperature, separated and washed several times with water. Product was dried at 40 ºC
.
Collagen (CO) modified MPs
Product was prepared in a similar manner to that above except for 10 ml of 1% collagen was used.
Graphene (GR) and glucose (GL) modified MPs
2

Suspension of maghemite nanoparticles in 80 ml of water were treated with glucose (1 g) and
0.1 g of graphene in ultrasonic bath Sonorex Digital 10p (Bandelin, Berlin, Germany) for 20 min. The mixture was then shaken for 4 h at room temperature, separated and washed several times with water. Product was dried at 40 ºC.
Graphene (GR) and gold (GO) modified MPs
Suspension of maghemite nanoparticles in 80 ml of water were mixed with 0.1 g of graphene in ultrasonic bath Sonorex Digital 10p (Bandelin, Berlin, Germany) for 20 min. After 1 h of stirring a solution of HAuCl4 (20 ml, 1 mM) was added. The solution was stirred for 1 h and a solution of trisodium citrate dihydrate (0.5 ml, 26.5 mg.ml
-1
) was added. The solution was stirred overnight, separated by magnet, washed with water and dried at 40 ºC.
S2: SECM and SEM characterization of magnetic modified particles
Scanning electrochemical microscope (SECM) consisted of 10 mm measuring platinum disc probe electrode with potential of +0.2 V. Another platinum disc electrode with O-ring as conducting substrate used potential of +0.3 V. During scanning, the particles were attached on the substrate platinum electrode by magnetic force from neodymium magnet, situated below the electrode. Platinum measuring electrode was moving from 20 µm above the surface. The mixture consisted of 5 % ferrocene in methanol mixed in ratio 1:1 with 0.05 % KCl in water
(v/v). Measuring was performed in teflon cell with volume of 1.5 ml according to the following parameters: amperometric mode, vertical scan was carried out in area 800 × 800
µm with rate 500 µm.s
-1
.
Structural and elemental composition of the MPs were characterised by an electron microscope (SEM). For documentation of the selected nanomaterials, a FEG-SEM MIRA
XMU instrument (Tescan, a.s, Brno, Czech Republic) was used. This model is equipped with
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a high brightness Schottky field emitter for low noise imaging at fast scanning rates. The
SEM was fitted with Everhart-Thronley type of SE detector, a high speed YAG scintillator based BSE detector, a panchromatic CL Detector and EDX spectrometer. The MIRA 3 XMU system is based on a large specimen chamber with motorized stage movements of 130 × 130 mm. Samples were coated by 10 nm of carbon to prevent charging. A carbon coater K950X
(Quorum Technologies, Grinstead, UK) was used. For automated acquisition of selected areas, a TESCAN proprietary software tool called Image Snapper was used. The software enables automatic acquisition of selected areas with defined resolution. Different conditions were used in order to obtain either minimum analysis time or maximum detail during overnight automated analysis. An accelerating voltage of 15 kV and beam currents of about 1 nA gave satisfactory results regarding maximum throughput.
S3: Spectrophotometric analysis using X-ray view (XRF)
Modified magnetic particles were measured on Spectro Xepos (Spectro Analytical
Instruments, Kleve, Germany). The sample was measured on Pd anode X-ray tube working at voltage of 47.63 kV and current of 0.5 mA and detection was carried out with Barkla scatter aluminium oxide. Measurement time was 300 s. For excitation Mo secondary target was used.
The excitation geometry was 90º. The sample was measured through the PE bottle side wall
20 mm above the bottom. The Spectro Xepos software and TurboQuant method were applied for data analysis. The first detector is HOPG and the second is Mo. The peaks are in the areas for which the excitation values are typical for Fe or Au.
S4: Cultivation of Staphylococcus aureus
The composition of cultivation medium was as it follows: tryptone 10 g.L
-1 , yeast extract 5 g.L
-
1
, NaCl 5 g.L
-1
(Himedia, Mumbai, India), sterilized MilliQ water with 18 MΩ. pH of the
4

cultivation medium was adjusted at 7.4 before sterilization. Sterilization of media was carried out at 121 °C for 30 min in sterilizer (Tuttnauer 2450EL, New York, USA). The prepared cultivation media were inoculated with bacterial culture into 25 ml Erlenmeyer flasks. After the inoculation, bacterial cultures were cultivated for 24 h on an Environmental Shaker-
Incubator ES-20 (Biosan, Riga, Latvia) at 600 rpm and 37 °C. Bacterial culture cultivated under these conditions was diluted by cultivation medium on Specord spectrophotometer 210
(Analytik, Jena, Germany) to OD
600
= 0.1 and used in the following experiments.
Petri dishes with a diameter of 9.5 cm were poured with 20 ml LB (Luria Bertani) agar which was prepared by dissolving individual components in sterilized miliQ water with 18 MΩ. The composition of cultivation medium was as it follows: tryptone 10 g.L
-1
, NaCl 5 g.L
-1
, yeast extract 5 g.L
-1
, agar extract 5 g.L
-1
(Himedia), pH of the cultivation medium was adjusted at
7.4 before sterilization. Sterilization of media was carried out at 121 °C for 30 minutes in sterilizer (Tuttnauer 2450EL, New York, USA). After medium solidification Petri dishes were inoculated with 0.1 ml of bacterial suspension from each concentration. After 30 minutes, when inoculum was dried, Petri dishes were cultivated with inoculum upside down at 37 °C.
After 24 hours of cultivation every typical colonies on the Petri dishes were counted and the conversion on colony forming units (CFU) per ml of sample using the formula N = m/V, where m is the number of colonies grown on Petri dishes, V is the volume of the inoculum used to cultivation and N is the number of colony forming units in 1 ml of sample.
S5 : UV/VIS spectrophotometry
Absorption spectra were recorded using a SPECORD 210 spectrophotometer (Analytik Jena,
Jena, Germany) at λ = 405 nm and λ = 600 nm. Quartz cuvettes with 1 cm optical path
(Hellma, Essex, UK) were used. The cell with cuvette was thermostated to 37 °C with a
Julabo thermostat (Labortechnik, Wasserburg, Germany). Absorption spectra were recorded
5

after 0, 20, 40, 60, 80, 100, 120 and 140 min of interaction with S. aureus and ALP kit were evaluated using the WinASPECT programme (Analytik Jena, Jena, Germany).
Automated spectrophotometric measurements were carried out using an chemical analyser
BS-400 (Mindray, Schenzen, China). It is composed of cuvette space tempered to 37±1 °C, reagent space with a carousel for reagents (tempered to 4±1 °C), sample space with a carousel for preparation of samples and an optical detector. Transfer of samples and reagents is provided by robotic arm equipped with a dosing needle (error of dosage up to 5 % of volume).
Cuvette contents are mixed by an automatic mixer including a stirrer immediately after addition of reagents or samples. Contamination is reduced due to its rinsing system, including rinsing of the dosing needle as well as the stirrer by MilliQ water.
Alkaline phosphatase (ALP) was determined in the suspensions of bacteria with culture medium of appropriate cell density ( OD
600
= 1.5). In a reaction catalysed by ALP the substrate p-nitrophenyl phosphate is split to p-nitrophenol and inorganic phosphate. ALP activity is determined kinetically and is based on the rate of p-nitrophenol concentration increase during reaction. Catalytic concentration of ALP is proportional to absorbance increase. Firstly, 205 μl volume of reagent R1 (Greiner, Frickenhausen, Germany, 0.9 M 2amino-2-methyl-1-propanol, pH 10.4, 1.6 mM MgSO
4
, 0.4 mM ZnSO
4
, 2 mM N-(2hydroxyethyl) ethylene diarnine triacetic acid) is pipetted into a plastic cuvette with subsequent addition of 5 μl of the bacterial suspensions. The mixture is left for 270 s to be incubated. Subsequently, 30 μl of reagent R2 (Greiner, Frickenhausen, Germany, 16 mM pnitrophenyl phosphate) is added and the solution is incubated for 90 s. After the incubation, absorbance was measured at 405 nm for 180 s. The mean increase of absorbance per minute is calculated and used for ALP assay.
Determination of Alkaline Phosphatase. The final volume of the reaction mixture was 240 µl.
Volumes of pipetted reagents R1 and R2 were adjusted so that the final concentrations of
6

substrate (p-nitrophenyl phosphate) in the reaction mixture were (0.4, 0.8, 1.3, 2.0, 2.7, 3.3,
4.0, 4.7, 5.3, 6.8 and 8 mM), pipetted volume of sample and reaction time were always constant 5 µl and 4.5 minutes, respectively.
7