Development of a DNA Biodosimeter for UV Radiation

Telma S. Marques

1,2

, Filipa Pires

, Gonçalo Magalhães-Mota

, Paulo A. Ribeiro

, Maria Raposo

and Nigel Mason

CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia,

Universidade Nova de Lisboa, 2829-516 Caparica, Portugal

Faculty of Science, Technology, Engineering and Mathematics, The Open University,

Walton Hall, Kents Hill, Milton Keynes MK7 6AA, U.K.

Keywords: DNA Calf Thymus, UV Radiation, Biodosimeters.

Abstract: Ultraviolet (UV) radiation has a strong influence in the damage of deoxyribonucleic acid (DNA). In this work,

the possibility of a DNA UV radiation dosimeter is evaluated. For that, calf thymus DNA samples, thin films

and aqueous solutions, were irradiated with 254 nm wavelength light during different periods of time, being

the damage caused by the irradiation analysed by both UV-visible and infrared spectroscopies. As the DNA

is a polyelectrolyte, the pH of the DNA samples was also considered as a variable. Results demonstrated that

damage in DNA takes place in both thin films and solutions when irradiated at 254 nm, as revealed by a

consistent decay in measured absorbance values. However, DNA solutions were seen to give more reliable as

the induced damage is easily measured. For this case, the absorbance at 260 nm was seen to exponentially

decrease with the irradiation time as a result of radiation damage with the kinetics damage strongly dependent

of pH. Consequently, the lifetime of such dosimeter device can be chosen by changing the pH of aqueous

solutions.

1 INTRODUCTION

The use of radiation for medical procedures, in

particular for diagnostic and therapy purposes, has

dramatically increased over the years (Yu, 2017).

Mechanisms of justification of procedures and

management of the patient dose are employed to

avoid unnecessary or unproductive radiation

exposure in diagnostic and interventional procedures.

Dose constrains are appropriated to comforters and

carers, and volunteers in biomedical research but

regarding the therapeutic applications, it is not

considered appropriate to apply dose limits or dose

constraints, because such limits would often do more

harm than good (ENEA2012).

The effects induced on biological systems by

electromagnetic radiation are due to the energy

transfer into the medium with absorption of the

radiation (Bernhardt, 1992, Bronzino, 1995, Moulder,

2007), and are characterized by a series of events

which differ (and are classified) according to their

reaction time scale, leading ultimately to biological

damage (Bernhardt, 1992). These events can thus be

divided into three groups: 1) Physical –interactions

between the charged particles and the tissues atomic

structures, which leads to ionization and concomitant

formation of ionic radicals, in an extremely short time

frame (around 10

-18

s); 2) Chemical – formation of ion

pairs through an ionization process, which leads to

formation of free radicals and chemical bonds rupture

(around 10

-6

s); and 3) Biological – follows from bond

rupture and is characterized by altering the proper

physiology of cells or even cells death (Moulder,

2007); the time that biological damage takes place

after chemical bonds rupture is usually long, ranging

from a few hours to several days, weeks, months, or

even years.

When a cell is irradiated there are two types of

changes which can occur, directly on the cellular

component molecules or indirectly on water

molecules, causing water-derived radicals. Radicals

react with nearby molecules in a very short time,

resulting in breakage of chemical bonds or oxidation

of the affected molecules. The major effect in cells is

DNA breaks (Gomes, 2014, Fretelde, 1993, Su, 1994,

Xu, 1994, Storhatf, 1999, Podgorsak, 2006). Ionizing

radiation can also lead to structural changes in several

macromolecules present in cells. In nucleic acids,

changes are essentially loss or damage of bases,

thymine dimmers formation, single or double strand

328

Marques, T., Pires, F., Magalhães-Mota, G., Ribeiro, P., Raposo, M. and Mason, N.

Development of a DNA Biodosimeter for UV Radiation.

DOI: 10.5220/0006732003280333

In Proceedings of the 6th International Conference on Photonics, Optics and Laser Technology (PHOTOPTICS 2018), pages 328-333

ISBN: 978-989-758-286-8

breaks and also DNA-protein dimmers formation

(Kielbassa, 1997, Ravanat, 2001).

DNA is featured an interesting anionic

polyelectrolyte having a unique double helix structure

(Fretelde, 1993) that can be used for many purposes.

For example, on the basis of hydrogen bonding

properties of DNA base pairs, oligonucleotide probes

have been recently designed to detect tumour gene

and various biosensors were also proposed (Caruso,

1999, Lvov, 1993). Also, DNA aqueous solutions are

of special interest, mainly in the development of

biological sensors (Su, 1994, Xu, 1994).

Moreover, the DNA sequence defines the genetic

information that commands the development of any

living being and its main vital functions (Wilkins,

1953, Franklin, 1953, Gomes, 2014). Since DNA

plays an important role in the maintenance of the

genetic information, any modification in this

macromolecule has significant effects at the cellular

level (Lindahl, 1993; Beckman and Ames, 1997).

Thus many efforts have been taken to delineate the

mechanisms of formation and the chemical structures

of the DNA modifications produced by genotoxic

compounds, including also ionizing (X, gamma,

heavy ions) and non-ionizing (ultraviolet (UV) and

visible light) radiations (Ravanat, 2016).

The effects of ionizing radiation on DNA have

been investigated in detail during the last three

decades but one of the most common environmental

health hazards that cause highly toxic effects is the

UV radiation (Kielbassa et al., 1997, Ravanat et al.,

2001, Yu and Lee, 2017). It should be referred here

that UV radiation is classified as UVA (315-400 nm),

UVB (290-315 nm), and UVC (280-100 nm). Most

UVC is absorbed by the ozone layer, and only UVA

and UVB compose ground level UV radiation

(Kalinnowski, 1999, Caruso, 1999). This is because,

firstly, certain biomolecules such as proteins and

nucleic acids have chromophores that absorb in the

UV region of the spectrum. Under high UV fluxes,

these molecules are photo-chemically degraded or

transformed, resulting in impairment or even

complete loss of biological function. The magnitude

of damage caused by these so-called direct or primary

mechanisms is determined by the amount of radiation

absorbed (absorbance cross-section) and the quantum

yield of photo-damage (molecules damaged per

photon absorbed).

One class of UV toxicity effects is caused by a

series of indirect mechanisms. UV is absorbed by

some intermediate compound (photosensitising

agent) either inside or outside the cell to produce

reactive oxygen species (ROS) (Vincent, 2000). The

resulting high energy oxidants such as hydrogen

peroxide, superoxide or hydroxyl radicals can then

diffuse and react with other cellular components with

sites of damage that can be well away from the site of

photo-production. Regarding genetic damage, nucleic

acid bases absorb maximally in the UVC range, with

peak absorbance around 260 nm, and exhibit a tail

that extends well into the UVB (Vincent, 2000). This

absorbed energy results in the first excited singlet

state, with a lifetime of only a few picoseconds. Most

of this energy is dissipated by radiation less processes

inside the molecule, but a small fraction is available

for a variety of chemical reactions. This can result in

the photo-damage of nucleotides (Vincent, 2000),

with a two- to four-fold greater effect on pyrimidines

(thymine and cytosine) relative to purines (adenine

and guanine). In addition, three principal

photoproducts are formed by the UV-induced

reactions: (a) 5,6-dipyrimidines, which are

cyclobutane-type dimers, generally referred to simply

as pyrimidine dimers; (b) photohydrates; and (c)

pyrimidine (6—4) pyrimidones, often referred to as

(6—4) photoproduct (Vincent, 2000). For example,

skin aging, eye damage, and skin cancer are some of

the most harmful effects known. This is because of

increased production of cellular reactive oxygen

species and by direct DNA damage, and if the DNA

damage is not properly repaired, will lead to

mutations and interferes with many cellular

mechanisms (e.g. replication, transcription, and the

cell cycle) (Yu, 2017).

If one intends to develop a device which allows

the measurement of light dose based on biological

materials, it should be chear that there are three kinds

of biologic markers: exposure (dose), effect and

susceptibility markers. Biologic markers of effect

record biologic responses in individuals who have

been exposed to a genotoxic agent, but markers of

dose do not necessarily indicate effects.

Superimposed on this are susceptibility markers;

those that could be used to identify persons who are

at increased risk of developing a disease that could be

triggered by a radiation exposure. Included here

might be organisms whose ability to repair DNA

damage is limited (National Research Council, 1995).

Biological dosimetry does not measure the

exposure in real time but the biological changes

induced by radiation. There are both indicators of

exposure or effects. Often the two aspects overlap as

in the case of deterministic effects induced by high-

doses, as for the acute radiation syndrome clinic that

is characterized by damages in skin, haematopoietic,

gastrointestinal, and cerebrovascular systems. In the

case of stochastic effects, induced by low doses, the

biomarkers used to measure the absorbed dose, not

Development of a DNA Biodosimeter for UV Radiation

329

always imply a clear detriment of health. It has been,

however, often demonstrated that an increase in the

frequency of these indicators is associated with an

increased risk of radiation-induced cancer and may be

indicative of radio-sensitivity (Giovanetti, 2012).

According to Giovanetti et al, 2012, for a

biodosimeter to be effective the following features are

determinant: 1) measurement on tissues or fluids

easily obtainable; 2) the effect must be specific of

radiation; 3) response should vary directly depending

on the dose; 4) it has to measure also chronic or

repeated exposure; 5) it must be possible to measure

retrospectively exposure also after years and 6) the

measurement must be simple, fast or automated.

A simple method of analyse the effect of UV

radiation on DNA is the measurement of AC

electrical conductivity of DNA thin films (Gomes,

2012). Such study revealed that electrical conduction

arises from DNA chain electron hopping between

base-pairs and phosphate groups being the hopping

distance a value of 3.38990.0002Å which coincides

with the distance between DNA base-pairs.

Moreover, the loss of conductivity of DNA samples

follow the decrease in phosphates groups with

irradiation time, suggesting the use of DNA based

films for UV radiation sensors (Gomes, 2012). Based

in these achievements, in this paper, a new biological

dosimeter based radiation-induced lesions in DNA is

proposed, where the damage caused by radiation is

obtained by UV-visible (UV-Vis) and infrared

spectroscopies and related to radiation exposure.

2 MATERIALS AND METHODS

Ultra-pure water and DNA hydrophilized in sodium

salt form (DNA sodium salt from calf thymus, CAS

73049-39-5, acquired from Fluka®) was used for the

preparation of DNA aqueous solutions. Its dissolution

is favoured by the presence of sodium ion (counter-

ion), allowing the preparation of aqueous solutions

with anionic character. The concentration of the DNA

solutions was 0.025 mg/mL DNA. The pH value of

the DNA aqueous solution was 6, these solutions are

also designated as natural solutions or pHN. In order

to obtain DNA solutions with pH=9 and pH=3, the

pH was adjusted to basic or acid with NaOH (1M) and

HCl (1M), respectively.

Cast films were obtained by the drop casting

method, i.e, depositing some drops of the DNA

aqueous solutions with different pHs onto calcium

fluoride (CaF

) solid supports. These samples were

placed in a desiccator during several hours to dry.

Solutions and cast films were irradiated for

different periods of time by means of a 254 nm UVC

germicide lamp, model TUV PL-L 55W/4P HF 1CT

from Philips

, at an irradiance of 1.9W/m

, in a

ventilated chamber at room conditions.

The DNA damage was monitored in aqueous

solutions by measurements of UV-Vis spectra after

each irradiation period in a spectrometer (UV

2101PC, Shimadzu

) while the thin films were

characterized with a Fourier transform infrared

(FTIR) spectrometer Thermo Scientific Nicolet-

model 530 (Waltham, MA, USA).

3 RESULTS AND DISCUSSION

According to Schuch et al (Schuch 2013), to develop

a reliable system for measure the UV light dose, one

have to search for material that would present the

most adequate features: (i) high transmittance to UVB

and UVA wavelengths; (ii) resistance to

environmental adversities; (iii) possibility of framing

the shape of the template according to the aim of the

experiment; and (iv) low cost. Having into account

such advices and the conclusions achieved by Gomes

et al (Gomes, 2012), it seemed that the use of DNA

thin films should be interesting for the development

of a UV dosimeter. Consequently, DNA cast films

deposited onto CaF

and quartz were prepared from

DNA aqueous solutions with pH 3, 6(N) and 9. These

films were irradiated with 254 nm UV radiation for

different periods of time and the UV-vis and infrared

spectra were measured for the different irradiation

times. As expected, in the absence of water, the

changes caused by radiation are minimal as can be

inferred from the infrared spectra of the DNA cast

films prepared from DNA aqueous solutions (pHN)

before and after UV irradiation for 15 h, displayed in

Figure 1. The observed peaks in the spectra are in

accordance with Gomes et al (Gomes, 2009) where

the infrared absorbance peaks were systematically

assigned to the respective DNA groups. Accordingly

the range of wavenumbers contained between 1250

and 900 cm

-1

are associated with the phosphate

backbone region while 1500–1250 cm

-1

and 1800–

1500 cm

-1

wavenumber regions are associated to

DNA bases vibrations influenced by the sugar

component and to DNA bases, respectively (Gomes,

2009).

Since UV radiation has effect on DNA phosphates

groups as demonstrated by Gomes et al (Gomes,

2015), the values of absorbance at 1097 cm

-1

assigned to the presence of symmetric 





stretching

of backbone in the DNA molecules (Gomes, 2009),

were plotted in Figure 2 as a function of the

AOMatSens 2018 - Special Session in Advanced Optical Materials, Sensors and Devices

330

Figure 1: FTIR spectra of DNA casted films prepared from

solutions at natural pH (pH 6) conditions before and after

irradiation with UV-light at 254nm wavelength during 900

min (15 h).

Figure 2: Absorbance at 1097 cm

-1

after baseline

subtraction versus irradiation time for the different DNA

cast films prepared from aqueous solutions with different

pHs.

irradiation time for samples prepared from DNA

aqueous having different pH. Generally, an

absorbance decay is observed. However, these

measurements are always tricky due to baseline

fluctuations and also if the molecules concentration

seen by the beam is not identical–leading to

absorbance deviations. To circumvent this drawback,

the analysis of the effect of UV radiation at 254 nm

was carried out on DNA aqueous solutions prepared

at different pHs. Figures 3 a), b) and c) present the

UV-vis spectra obtained for the DNA aqueous

solutions with pH=3, pH=6 and pH=9, respectively,

irradiated during different periods of time. The

obtained results point out that the DNA solutions with

pH=3 (Figure 3 a) tend to be more sensitive to higher

times of UV light exposure since the absorbance at

260 nm for 900 minutes of irradiation was the lowest

value found for the different DNA solutions studied.

The baselines changes can be due to the light

scattering of smaller molecules, originated by the

cleavage of DNA molecule during the irradiation, as

demonstrated by Gomes et al, 2012.

Figure 3: Absorption spectra of DNA solutions with: a)

pH=3; b) pH=6 (natural) and c) pH=9; irradiated with 254

nm wavelength light for different periods of time.

The obtained results are in accordance with

literature as similar behaviours and patterns are

observed by Chen et al., 2009, where the disinfection

of water was studied and they present the effect of UV

radiation on the spores.

For a better comparison, the absorbance values at

260 nm, after removing the baseline (i.e. subtracting

the value of the absorbance at 350 nm), were

normalized, for each pH, and plotted as a function of

the irradiation time in figure 4. Several attempts have

1000 1200 1400 1600 1800

0.04

0.06

0.08

Absorbance

Wavenumber (cm

-1

)

0 (min)

900 (min)

0 200 400 600 800 1000

0,002

0,004

0,006

0,008

0,010

0,012

0,014

Absorbance

Irradiation Time (min)

pH=3

pH=N

pH=9

1097 cm

-1

200 300 400

0.0

0.1

0.2

0.3

0.4

0.5

Absorbance

Wavelenght (nm)

0 (min)

5 (min)

10 (min)

15 (min)

30 (min)

45 (min)

60 (min)

120 (min)

180 (min)

900 (min)

pH=3

200 300 400

0.0

0.1

0.2

0.3

0.4

0.5

Absorbance

Wavelenght (nm)

0 (min)

5 (min)

10 (min)

15 (min)

30 (min)

45 (min)

60 (min)

120 (min)

180 (min)

900 (min)

Natural pH

200 300 400

0.0

0.1

0.2

0.3

0.4

0.5

Absorbance

Wavelenght (nm)

0 (min)

5 (min)

10 (min)

15 (min)

30 (min)

45 (min)

60 (min)

120 (min)

180 (min)

900 (min)

pH=9

Development of a DNA Biodosimeter for UV Radiation

331

been done to find the best equation to model the

experimental data. The normalized experimental data







was found to be best fitted by an exponential

like expression as follows:

 









 











(1)

in which 



is the absorbance at 260 nm,





corresponds to the initial (at the

beginning of the experiments) absorbance at 260 nm,

t the time in minutes, τ is the characteristic time or

time constant and n is a constant which can be related

with the order of the kinetics process (Raposo, 1997)

with respect to radiation damage.

Figure 4: Normalized absorbance at 260 nm after removing

the baseline versus irradiation time for the different

solutions. The lines correspond to the fitting with equation

(1).

Figure 5 shows the plot of the time constants in

minutes for each pH. The results show that DNA

solutions at higher pH (more basic) can be exposed to

UV light during more time. Moreover, from equation

(1) one can propose an expression for the dose level

to which the sample has been subjected, as follows:

  

















(2)

in which D is the dose calculated by multiplying the

irradiance by the irradiation time, C

is the

characteristic dose constant and n is the order

parameter of the damage kinetics. These parameters

as well as the characteristic time constants are

presented in Table 1 for each pH investigated. From

the obtained results one can conclude that DNA

solutions can be suitable for the measurement of 254

nm wavelength light dose, being the lifetime of such

dosimeter device dependent of solution pH. To

develop a DNA based dosimeter device to cover also

UV A and UV B region, DNA damage has also to be

investigated in these UV regions. According with

previous results (Gomes, 2015), damage is expected

also take place with 300 nm wavelength light in such

a way that the same procedure described here should

be used to analyse the DNA damage when the

solutions are irradiated with higher wavelength light.

Figure 5: Time constant obtained by equation 1 versus pH

of the solutions irradiated and estimated dose for the

constant time for the solutions irradiated.

Table 1: Coefficients determined to each pH of DNA

solution irradiated.



(min)

(Wm

-2

.min)

2050±40

3890±70

0.571±0.005

3500±200

6700±300

0.90±0.03

8300±300

15800±600

0.590±0.007

4 CONCLUSIONS

In this work it was demonstrated that aqueous DNA

solutions can be used to probe UV radiation at 254

nm and to evaluate the radiation dose at 254 nm,

through absorbance measurements. The absorbance

was seen to exponentially decrease with irradiation

time being the damage kinetics parameter dependent

of pH DNA aqueous solutions. This work also

evidenced that the lifetime of such DNA dosimeter

device can be chosen changing the pH of those

solutions. In the future we intent to 1) irradiate the

samples with a fixed wavelength of 300 nm in order

to check the new kinetics damage; 2) check if there is

a linear correspondence to the irradiation power; and

3) study the sensibility of the potential sensor.

ACKNOWLEDGEMENTS

The authors acknowledge the financial support from

FEDER, through Programa Operacional Factores de

0 200 400 600 800 1000

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

Normalized absorbance at 260 nm

Irradiation time (minutes)

pH3

pHN

pH9

Fitting (pH=3)

Fitting (pH=N)

Fitting (pH=9)

3 4 5 6 7 8 9

1000

2000

3000

4000

5000

6000

7000

8000

9000

Time constant

Dose at constant time

Time constant (min)

2000

4000

6000

8000

10000

12000

14000

16000

18000

Dose (W/m

.min)

AOMatSens 2018 - Special Session in Advanced Optical Materials, Sensors and Devices

332

Competitividade—COMPETE and Fundação para a

Ciência e a Tecnologia—FCT, by the project

PTDC/FIS-NAN/0909/2014 and for the Portuguese

research Grants No. PEst-OE/FIS/UI0068/2011 and

UID/FIS/00068/2013. Telma Marques and Filipa

Pires acknowledge the fellowships

SFRH/BD/106032/2015 and PD/BD/106036/2015,

respectively from RABBIT Doctoral Programme

(RaBBiT, PD/00193/2012), Portugal.

REFERENCES

Bernhardt, J. H., 1992. Non-ionizing radiation safety:

Radiofrequency radiation, electric and magnetic fields.

Phys. Med. Biol. 37,807-844.

Bronzino, J.D., 1995. The biomedical engineering

handbook. CRC Press & IEEE Press. 2nd edition.

Caruso, F., Möhwald, H., 1999. Protein Multilayer

Formation on Colloids through a Stepwise Self-

Assembly Technique. Contribution from the Max

Planck Institute of Colloids and Interfaces, D-14424

Potsdam, Germany. J. Am. Chem. Soc., 1999, 121 (25),

6039–6046.

Chen, R.Z., Craik, S.A., Bolton, J.R. 2009. Comparison of

the action spectra and relative DNA absorbance spectra

of microorganisms: Information important for the

determination of germicidal fluence (UV dose) in an

ultraviolet disinfection of water. Water Research.

43(20):5087-96.

Franklin, R.E., Gosling, R.G., 1953. Evidence for 2-Chain

Helix in Crystalline Structure of Sodium

Deoxyribonucleate. Nature, 172, 156.

Giovanetti, A., Sgura, A., Aversa, G., 2012. Biological

Dosimetry - How to Measure the Absorbed Dose in

Different Scenarios. ENEA - Italian national agency for

new technologies, energy and sustainable economic

development. Rome. ISBN: 978-88-8286-264-0.

Gomes, P.J., 2014. Characterization of molecular damage

induced by UV photons and carbon ions on biomimetic

heterostructures. PhD Dissertation, FCT/UNL,

Portugal.

Gomes, P. J., Coelho, M., Dionísio, M., Ribeiro, P.A.,

Raposo, M., 2012. Probing radiation damage by

alternated current conductivity as a method to

characterize electron hopping conduction in DNA

molecules. Applied Physics Letters, 101, 123702.

Gomes, P.J., Ferraria, A. M., Botelho do Rego, A. M.,

Hoffmann, S.V., Ribeiro, P.A., Raposo, M., 2015.

Energy Thresholds of DNA Damage Induced by UV

Radiation: An XPS Study. The journal of Physical

Chemistry B, 119 (17) 5404- 5411.

Gomes, P.J., Ribeiro, P.A., Shaw, D., Mason, N.J. and

Raposo, M., 2009. UV degradation of deoxyribonucleic

acid. Polymer Degradation and Stability, 94(12) pp.

2134–2141.

Kielbassa, C., Roza, L., Epe, B., 1997. Wavelength

dependence of oxidative DNA damage induced by UV

and visible light. Carcinogenesis, 18, 811.

Lvov, Y., Decher, G., Sukhorukov, G., 1993. Assembly of

thin films by means of successive deposition of

alternate layers of DNA and poly(allylamine).

Macromolecules. 26 (20), pp 5396–5399.

Moulder, J., 2007. Power Lines, Cancer FAQ’s.

Electromagnetic Fields and Human Health. J.E. USA.

National Research Council, 1995. Chapter 6 - Biologic

Dosimetry and Biologic Markers: Growing public

concern about. Radiation Dose Reconstruction for

Epidemiologic Uses. Washington, DC: The National

Academies Press. ISBN: 978-0-309-05099-9.

Podgorsak, E.B., 2006. Radiation Physics for Medical

Physicist. Springer, Heidelberg. ISBN 978-3-642-

00875-7.

Raposo, M., Pontes, R.S., Mattoso, L.H.C., Oliveira

O.N.Jr., 1997. Kinetics of Adsorption of Poly (o-

methoxyaniline) Self-assembled films.

Macromolecules, 30, 6095-6101.

Ravanat, J.L., Douki, T., 2016., UV and ionizing radiations

induced DNA damage, differences and similarities.

Radiat. Phys. Chem.

https://doi.org/10.1016/j.radphyschem.2016.07.000.

Ravanat, J.L., Douki, T. and Cadet, J., 2001. Direct and

Indirect Effects of UV Radiation on DNA and Its

Components. Journal of Photochemistry and

Photobiology B: Biology, 63, 1-3, 88-102.

Schuch A.P., Garcia C.C., Makita K., Menck C.F., 2013.

DNA damage as a biological sensor for environmental

sunlight. Photochem. Photobiol. Sci., 2013, 12, 1259-

1272.

Su, H., Kallury, K.M.R., Thompson, M., Roach, A., 1994.

Interfacial Nucleic Acid Hybridization Studied by

Random Primer 32P Labeling and Liquid-Phase

Acoustic Network Analysis. Anal.Chem. 66, 769.

Vincent, W.F., Neale, P.J., 2000. 6 - Mechanisms of UV

damage to aquatic organisms. The Effects of UV

Radiation in the Marine Environment. Cambridge

University Press.

Wilkins, M.H., Stokes, A.R., Wilson, H.R., 1953.

Molecular Structure of Nucleic Acids: Molecular

Structure of Deoxypentose Nucleic Acids. Nature, 171,

738.

Xu, X.H., Yang, H.C., Mallouk, T.E., Bard, A.J., 1994.

Immobilization of DNA on an Aluminum (III)

Alkanebisphosphonate Thin Film with

Electrogenerated Chemiluminescent Detection.

J.Am.Chem.Soc. 116, 8386.

Yu, S.L., Lee, S.K., 2017. Ultraviolet radiation: DNA

damage, repair, and human disorders. Mol Cell Toxicol,

13:21-28.

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333