Molecular events on the nanometer scale can be detected by visible light without the need of fluorescence or colorimetric labels. These “label-free” sensors enable the real-time monitoring of binding, hence contributing to unravel the physics beyond molecular recognition processes. This also allows the realization of novel biosensing devices characterized by ease-of-use and rapidity.

To this aim, novel optical configurations are developed and molecular layers with controlled functionality are investigated. In particular, DNA-nanotechnology tools are exploited to design self-assembled molecular structures with enhanced binding strength and responsiveness.

Phantom materials

Fluorinated polymer materials can be designed to have a refractive index very close to that of water. In this condition, these plastic materials are barely visible when immersed in water and, therefore they are called “phantom”. Thin molecular layers on their surface can produce an easily detectable optical signal due to reflectance or scattering. Suitable optical models combined with kinetics and transport effects enable the quantification of the molecules adhering to the surface.

Microfluidic chips embedding different types of phantom materials, from planar prisms to micro-porous membranes or micro-beads, are designed and realized with the aim of studying the molecular interaction with the surface and to create new concepts of optical sensors.

Protein folding

Folding of simple proteins is typically a spontaneous and repeatable process. Experiments on small proteins commonly show only two populations of molecules at equilibrium: folded (native) and unfolded (denatured). Research on protein folding aims to understand which of the many possible amino acid sequences may be able to fold up and how the detailed structure of a folded protein can be predicted from its amino acid sequence. Solving the folding problem may have enormous implications: genetic diseases could be treated more effectively and exact drugs could be designed theoretically without a great deal of experimentation.

Several mechanism are presumably involved in the complex process of protein folding. One of the simplest and most fundamental events taking place during the folding of a polypeptide is the formation of contacts between two specific chain residues. Measuring the rate of contact formations between two specific amino acids of the same chain provides a tool for the characterization of the elusive unfolded state in native conditions.

Selected publications

1. G. Nava, L. Casiraghi, T. Carzaniga, G. Zanchetta, M. Chiari, F. Damin, V. Bollati, L. Signorini, S. Delbue, T. Bellini, M. Buscaglia, “Digital Detection of Single Virus Particles by Multi‐Spot, Label‐Free Imaging Biosensor on Anti‐Reflective Glass”, Small, 19, 2300947 (2023). 

2. G. Zanchetta, T. Carzaniga, L. Vanjur, L. Casiraghi, G. Tagliabue, C. Morasso, T. Bellini, M. Buscaglia, “Design of a rapid, multiplex, one-pot miRNA assay optimized by label-free analysis”, Biosensors and Bioelectronics, 172, 112751 (2021). 

3. L. Vanjur, T. Carzaniga, L. Casiraghi, M. Chiari, G. Zanchetta, M. Buscaglia, “Non-Langmuir Kinetics of DNA Surface Hybridization”, Biophysical Journal, 119, 989-1001 (2020). 

4. R. Lanfranco, F. Giavazzi, T. Bellini, E. Di Nicolò, M. Buscaglia, “Fabrication and Optical Modeling of Micro‐Porous Membranes Index‐Matched with Water for On‐Line Sensing Applications”, Macromolecular Materials and Engineering, 305, 1900701 (2020). 

5. A. Soranno, F. Cabassi, M. E. Orselli, T. Cellmer, A. Gori, R. Longhi, M. Buscaglia, “Dynamics of Structural Elements of GB1 β-Hairpin Revealed by Tryptophan−Cysteine Contact Formation Experiments”, Journal of Physical Chemistry B, 122, 11468−11477 (2018). 

6. R. Lanfranco, J. Saez, E. Di Nicolò, F. Benito-Lopez, M. Buscaglia, “Phantom membrane microfluidic cross-flow filtration device for the direct optical detection of water pollutants”, Sensors and Actuators B: Chemical, 257, 924-930 (2018). 

7. G. Zanchetta, R. Lanfranco, F. Giavazzi, T. Bellini, M. Buscaglia, “Emerging applications of label-free optical biosensors”, Nanophotonics, 6, 627-645 (2017). 

8. R. Lanfranco, F. Giavazzi, M. Salina, G. Tagliabue, E. Di Nicolò, T. Bellini, and M. Buscaglia, “Selective Adsorption on Fluorinated Plastic Enables the Optical Detection of Molecular Pollutants in Water”, Physical Review Applied 5, 054012 (2016).

9. M. Salina, F. Giavazzi, E. Ceccarello, F. Damin, M. Chiari, M. Ciuffo, G. P. Accotto, M. Buscaglia, “Multi-spot, label-free detection of viral infection in complex media by a non-reflecting surface”, Sensor and Actuators B, 223, 957-962 (2016).

10. M. Salina, F. Giavazzi, R. Lanfranco, E. Ceccarello, L. Sola, M. Chiari, B. Chini, R. Cerbino, T. Bellini, M. Buscaglia, “Multi-spot, label-free immunoassay on reflectionless glass”, Biosens Bioelectron, 74, 539-545 (2015).

11. F. Giavazzi, M. Salina, E. Ceccarello, A. Ilacqua, F. Damin, L. Sola, M. Chiari, B. Chini, R. Cerbino, T. Bellini, M. Buscaglia, “A fast and simple label-free immunoassay based on a smartphone”, Biosens Bioelectron, 58, 395-402 (2014).

12. F. Giavazzi, M. Salina, R. Cerbino, M. Bassi, D. Prosperi, E. Ceccarello, F. Damin, L. Sola, M. Rusnati, M. Chiari, B. Chini, T. Bellini, M. Buscaglia, “Multispot, label-free biodetection at a phantom plastic–water interface”, PNAS, 110, 9350-9355 (2013).

13. T. Araki, M. Buscaglia, T. Bellini, H. Tanaka, "Memory and topological frustration in nematic liquid crystals confined in porous materials", Nature Materials, 10, 303309 (2011).

14. T. Cellmer*, M. Buscaglia*, E. R. Henry, J. Hofrichter, W. A. Eaton, "Making connections between ultrafast protein folding kinetics and molecular dynamics simulations", PNAS, 108, 6103-6108 (2011).

15. M. Buscaglia, G. Lombardo, L. Cavalli, R. Barberi, T. Bellini, "Elastic anisotropy at a glance: the optical signature of disclination lines", Soft Matter, 6, 5434-5442, (2010).

16. A. Soranno, R. Longhi, T. Bellini, M. Buscaglia, "Kinetics of contact formation and end-to-end distance distributions of swollen dosordered peptides", Biophysical Journal, 96, 1515-1528 (2009).

17. M. Buscaglia, T. Bellini, C. Chiccoli, F. Mantegazza, P. Pasini, M. Rotunno, C. Zannoni, "Memory effects in nematics with quenched disorder", Physical Review E, 74, 011706 (2006).

18. M. Buscaglia, L. J. Lapidus, W. A. Eaton, J. Hofrichter, "Effects of Denaturants on the Dynamics of Loop Formation in Polypeptides", Biophysical Journal, 91, 276-288 (2006).

19. M. Buscaglia, J. Kubelka, W. A. Eaton, J. Hofrichter, "Determination of ultrafast protein folding rates from loop formation dynamics", Journal of Molecular Biology, 347, 657-664 (2005).

20. M. Buscaglia, B. Schuler, L. J. Lapidus, W. A. Eaton, J. Hofrichter, "Kinetics of Intramolecular Contact Formation in a Denatured Protein", Journal of Molecular Biology, 332, 9-12 (2003).

Teaching

From 2020 teaching duty of Molecular Biophysics for the master's degree in Quantitative Biology. From 2010 teaching duty of Fluorescence Methods for the PhD course Experimental Methods for the Systems at the Nanoscale. From 2005 teaching duties of Medical Physics, Optics and Digital Image Processing for different bachelor and master's degrees courses of the Faculty of Medicine and Surgery. 

Contact

Department of Medical Biotechnology and Translational Medicine
via F.lli Cervi 93, 20054 Segrate (MI)
Università degli studi di Milan
Phone +39 02503 30352
E-mail: marco.buscaglia@unimi.it

Vacancies

Inquiries are welcome for experimental research projects on molecular biophysics and/or optical biosensors either for bachelor or master's degree thesis or PhD positions.
Feel free to contact via email at marco.buscaglia@unimi.it

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