Andreas DahlinChalmers University of Technology · Department of Chemistry and Chemical Engineering
Andreas Dahlin
Professor
Research, teaching and utilization.
About
84
Publications
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Introduction
I work with functional nanostructures: In my group we
fabricate new structures and functionalize them chemically in order to evaluate them for various applications. Our work is strongly interdisciplinary and we aim to develop new bioanalytical devices or synthetic biological systems on the nanoscale. We are also addressing fundamental scientific questions, for instance within supramolecular chemistry and polymer physics.
Please see my webpage adahlin.com for further information!
Additional affiliations
March 2012 - October 2016
August 2011 - February 2012
August 2009 - July 2011
Education
August 1999 - June 2004
Publications
Publications (84)
Gold nanoparticles possess unique photothermal properties and have gained considerable interest in biomedical research, particularly for photothermal therapy (PTT). This study focuses on evaluating the photothermal properties of gold nanorods (AuNRs) supported on glass substrates upon excitation with near-infrared (NIR) light. Two aspect ratios of...
Reflective pixels made by plasmonic metasurfaces and tuned by electrochromics exhibit significant potential to be used as flexible, polychromatic, electronic paper. This is attributed to their high reflectivity, low power consumption, and ultrathin dimensions. However, to date, only single pixels of electrochromics combined with plasmonics have bee...
Recent years have shown many advances in the development of tunable structural colors by combining nanostructures with electrochromic materials. One main goal is to develop energy saving color displays that rely on ambient light instead of being emissive. However, all displays need to be pixelated to show arbitrary images and few studies have addre...
The worldwide spread of SARS-CoV-2 has been characterised by the emergence of several variants of concern (VOCs) presenting an increasing number of mutations in the viral genome. The spike glycoprotein, responsible for engaging the viral receptor ACE2, exhibits the highest density of mutations, suggesting an ongoing evolution to optimize viral entr...
The possibility to detect and analyze single or few biological molecules is very important for understanding interactions and reaction mechanisms. Ideally, the molecules should be confined to a nanoscale volume so that the observation time by optical methods can be extended. However, it has proven difficult to develop reliable, non-invasive trappin...
Dynamically-tunable reflective structural colors are attractive for reflective displays (electronic paper). However, it has been challenging to tune a thin layer of structural color across the full red-green-blue (RGB) basis set of colors at video rates and with long-term stability. Here, this is achieved through a hybrid cavity built from metal-in...
In nanobiotechnology, the importance of controlling interactions between biological molecules and surfaces is paramount. In recent years, many devices based on nanostructured silicon materials have been presented, such as nanopores and nanochannels. However, there is still a clear lack of simple, reliable, and efficient protocols for preventing and...
Electrochromic materials and their implementation with structural colors are currently being intensely researched because of their promising applications as non-emissive display devices utilizing ambient light. In particular, several fully inorganic devices that rely on electrochromic tungsten trioxide (WO3) have been presented. For preparing nanos...
Recent advances in nanofabrication technologies have enabled new ways to produce structural colors. By combining nanofabrication methods, it is possible to integrate electrochromic materials with the nanostructures, which enable electrical tuning of the colors and thus new types of reflective displays. Previous work has shown high quality colors an...
Low‐cost, flexible and thin display technology is becoming an interesting field of research as it can accompany the wide range of sensors being developed. Here, the synthesis of poly(dimethylpropylene‐dioxythiophene) (PProDOT‐Me2) by combining vapor phase polymerization and screen printing is presented. A multilayer architecture using poly(3,4‐ethy...
The nuclear pore complex is a nanoscale assembly that achieves shuttle-cargo transport of biomolecules: a certain cargo molecule can only pass the barrier if it is attached to a shuttle molecule. In this review we summarize the most important efforts aiming to reproduce this feature in artificial settings. This can be achieved by solid state nanopo...
Plasmonic metasurfaces for color generation are emerging as important components for next generation display devices. Fabricating bright plasmonic colors economically and via easily scalable methods, however, remains difficult. Here, the authors demonstrate an efficient and scalable strategy based on colloidal lithography to fabricate silver‐based...
Interfaces functionalized with polymers are known for providing excellent resistance towards biomolecular adsorption and for their ability to bind high amounts of protein while preserving their structure. However, making an interface that switches between these two states has proven challenging and concepts to date rely on changes in the physiochem...
Surface plasmon resonance is a very well-established surface sensitive technique for label-free analysis of biomolecular interactions, generating thousands of publications each year. An inconvenient effect that complicates interpretation of SPR results is the "bulk response" from molecules in solution, which generate signals without really binding...
Surface plasmon resonance (SPR) is a highly useful technique in biology and is gradually becoming useful also for materials science. However, measurements to date have been performed almost exclusively on gold, which limits the possibility to probe chemical modifications of other metals. In this work we show that 20 nm Pd and Pt films work "fairly...
Dynamic control of structural colors across the visible spectrum with high brightness has proven to be a difficult challenge. Here, this is addressed with a tuneable reflective nano‐optical cavity that uses an electroactive conducting polymer (poly(thieno[3,4‐b]thiophene)) as spacer layer. Electrochemical doping and dedoping of the polymer spacer l...
Reflective displays or “electronic paper” technologies provide a solution to the high energy consumption of emissive displays by simply utilizing ambient light. However, it has proven challenging to develop electronic paper with competitive image quality and video speed capabilities. Here, the first technology that provides video speed switching of...
Here, the research field of nanoplasmonic sensors is placed under scrutiny, with focus on affinity-based detection using refractive index changes. This review describes how nanostructured plasmonic sensors can deliver unique advantages compared to the established surface plasmon resonance technique, where a planar metal surface is used. At the same...
Background
Transrectal prostate biopsy (TRbx) transfers colonic bacteria into prostatic tissue, potentially causing infectious complications, including sepsis. Our objective was to determine whether biopsy needle shape, surface properties and sampling mechanism affect the number of bacteria transferred through the colon wall, and evaluate a novel n...
The possibility of actively controlling structural colors has recently attracted a lot of attention, in particular for new types of reflective displays (electronic paper). However, it has proven challenging to achieve good image quality in such devices, mainly because many subpixels are necessary and the semitransparent counter electrodes lower the...
Polymer brushes are widely used to alter the properties of interfaces. In particular, poly(ethylene glycol) (PEG) and similar polymers can make surfaces inert toward biomolecular adsorption. Neutral hydrophilic brushes are normally considered to have static properties at a given temperature. As an example, PEG is not responsive to pH or ionic stren...
Nuclear Pore Complexes (NPCs) regulate bidirectional transport between the nucleus and the cytoplasm. Intrinsically disordered FG-Nups line the NPC lumen and form a selective barrier, where transport of most proteins is inhibited whereas specific transporter proteins freely pass. The mechanism underlying selective transport through the NPC is still...
The synthesis and thermoresponsive properties of surface-attached poly(N-isopropylacrylamide)-co-N,N′-methylene bisacrylamide (PNIPAM-co-MBAM) networks are investigated. The networks are formed via SI-ARGET-ATRP (“grafting-from”) on thiol-based initiator-functionalized gold films. This method is reliable, well controlled, fast, and applicable to pa...
We report for the first time that the protonation behavior of weak polyelectrolyte brushes depends very strongly on ionic strength. The pKa changes by one pH step per order of magnitude in salt concentration. For low salt concentrations (~1 mM), very high pH is required to deprotonate a polyacidic brush and very low pH is required to protonate a po...
Plasmonic structural colors have recently received a lot of attention. For many applications there is a need to actively tune the colors after preparing the nanostructures, preferably with as strong changes in the optical response as possible. However, to date there is a lack of systematic investigations on how to enhance contrast in electrically i...
Techniques for immobilization and release of proteins are of general interest but challenging to develop. Here we show a new method for high-capacity (several µg/cm2) immobilization of proteins in polyelectrolyte...
Solid state nanopores are central structures for many applications. To date, much effort has been spent on controlled fabrication of single nanopores, while relatively little work has focused on large...
Catalysis by enzymes on surfaces has many applications. However, strategies for efficient enzyme immobilization with preserved activity are still in need of further development. In this work we investigate polyelectrolyte brushes prepared by both grafting-to and grafting-from with the aim to achieve high catalytic activity. For comparison, self-ass...
Biosensors based on plasmonic nanostructures are widely used in various applications and benefit from numerous operational advantages. One type of application where nanostructured sensors provide unique value in comparison with, for instance, conventional surface plasmon resonance, is investigations of the influence of nanoscale geometry on biomole...
In recent years there has been a growing interest in the use of plasmonic nanostructures for color generation, a technology that dates back to ancient times. Plasmonic structural colors have several attractive features but once the structures are prepared the colors are normally fixed. Lately, several concepts have emerged for actively tuning the c...
Biosensors based on plasmonic nanostructures offer label-free and real-time monitoring of biomolecular interactions. However, so do many other surface sensitive techniques with equal or better resolution in terms of surface coverage. Yet, plasmonic nanostructures offer unique possibilities to study effects associated with nanoscale geometry. In thi...
Polymer brushes are widely used as surface coatings for various inert, functional, or responsive interfaces. If the polymer can alter its protonation state (a polyelectrolyte (PE)), the brush can switch between a collapsed and swollen state with pH, which enables applications such as nanoscale actuators. However, changes in brush height as the poly...
Antibody-antigen interactions are complex events central to immune response, in vivo and in vitro diagnostics, and development of therapeutic substances. We developed an ultrastable single-molecule localized surface plasmon resonance (LSPR) sensing platform optimized for studying antibody-antigen interaction kinetics over very long time scales. The...
Control of molecular translocation through nanoscale apertures is of great interest for DNA sequencing, biomolecular filters, and new platforms for single molecule analysis. However, methods for controlling the permeability of nanopores are very limited. Here, we show how nanopores functionalized with poly(ethylene glycol) brushes, which fully prev...
Nanoplasmonic sensors have emerged as a promising measurement approach to track biomacromolecular interactions involving lipid membrane interfaces. By taking advantage of nanoscale fabrication capabilities, it is possible to design sensing platforms with various architectural configurations. Such capabilities open the door to fabricating lipid memb...
Polymer brushes are widely used to prevent adsorption of proteins, but the mechanisms by which they operate remain heavily debated since many decades. We show conclusive evidence that a polymer brush can be a remarkably strong kinetic barrier towards proteins by using poly(ethylene glycol) grafted to the sidewalls of pores in 30 nm thin gold films....
During the last 20 years, the use of nanopore membranes to separate molecules depending on their size, charge or other characteristics, have increased in interest. These more ordered and defined nanopores have several advantages compared to traditional ultrafiltration membranes and provide possibilities to combine with, e.g., both electrical and op...
Poly(ethylene glycol) (PEG) is widely used in biotechnology-related applications yet its temperature-dependent functionality is not well understood. Here, we use bovine serum albumin (BSA) monomers and cross-linked dimers to directly probe the height of strongly stretched PEG brushes using surface plasmon resonance (SPR) in aqueous solution. Our re...
Plasmonic color generation offers several advantages but is also limited by the cost and availability of noble metals like gold. In this work we present color-tuneable metasurfaces with high chromaticity and reflectivity consisting of an aluminum mirror, a dielectric spacer and a plasmonic nanohole array in copper. Copper is shown to be an excellen...
Plasmonic nanostructures are widely used for various sensing applications by monitoring changes in refractive index through optical spectroscopy or as substrates for surface enhanced Raman spectroscopy. However, in most practical situations conventional surface plasmon resonance is preferred for biomolecular interaction analysis because of its high...
Localized surface plasmon resonance (LSPR) biosensing based on supported metal nanoparticles offersunparalleled possibilities for high-end miniaturization, multiplexing and high-throughput label-free molecular interaction analysis in real time when integrated within an opto-fluidic environment. However, such LSPR
sensing devices typically contain e...
Polymerization from surfaces and the resulting “brushes” have many uses in the development of novel materials and functional interfaces. However, it is difficult to accurately monitor the polymerization rate, which limits the use of polymer brushes in applications where control of thickness is desirable. We present a new methodology based on angula...
method provides high polarization-independent resonant reflection (>90% in air), good contrast (30–50%), fast response times (ms regime), ultralow power consumption (<0.5 mW cm −2), and long-term stability. We also show that plasmonic metasur-faces containing pixels of the primary colors red–green–blue (RGB) give the same reflectivity and contrast...
Accurate concentration determination of subpopulations of extracellular vesicles (EVs), such as exosomes, is of importance both in the context of understanding their fundamental biological role and of potentially using them as disease biomarkers. In principle, this can be achieved by measuring the rate of diffusion-limited mass uptake to a sensor s...
Plasmonic nanohole arrays are widely used for optical label-free molecular detection. An important factor for many applications is the diameter of the apertures. So far nanohole arrays with controllable diameters below 100 nm have not been demonstrated and it has not been systematically investigated how the diameter influences the optical propertie...
The biochemical processes of cell membranes are sensitive to the geometry of the lipid bilayer. We show how plasmonic "nanowells" provide label-free real-time analysis of molecules on membranes with detection of preferential binding at negative curvature. It is demonstrated that norovirus accumulate in invaginations due to multivalent interactions...
Emission of photoexcited hot electrons from plasmonic metal nanostructures to semiconductors is key to a number of proposed nanophotonics technologies for solar harvesting, water splitting, photo catalysis and a variety of optical sensing and photodetector applications. Favorable materials and catalytic properties make systems based on gold and TiO...
We present a new grafting-to method for resistant "non-fouling" poly(ethylene glycol) brushes, which is based on grafting of polymers with reactive end groups in 0.9 M Na2SO4 at room temperature. The grafting process, the resulting brushes and the resistance towards biomolecular adsorption are investigated by surface plasmon resonance, quartz cryst...
A review of sensing applications based on plasmonic nanopores is given. Many new types of plasmonic nanopores have recently been fabricated, including pores penetrating multilayers of thin films, using a great variety of fabrication techniques based on either serial nanolithography or self-assembly. One unique advantage with nanopores compared to o...
We evaluate and compare the sensitivity of gold nanodisks on silica substrates and nanoholes made in silica-supported gold films, two of the most common sensor structures used in plasmonic biosensing. An alumina overcoat was applied by atomic layer deposition (ALD) to precisely control the interfacial refractive index and determine the evanescent p...
A novel type of plasmonic nanopore array in a metal–insulator–metal thin film is presented. The optical properties of this structure are described using a generic theoretical framework for surface waves in a coupled multilayer system. The characteristic spacing (short-range order) of the pores enables grating-type coupling to hybridized surface pla...
We have created a simple and efficient thermal plasmonic sensor platform by letting a DC current heat plasmonic nanohole arrays. This sensor can be used to determine thermodynamic parameters in addition to monitoring molecular reactions in real-time. We use the thermal sensor to determine the kinetics and activation energy for desorption of thiol m...
The sensitivity of a surface plasmon to the dielectric environment makes it a viable tool in detecting single molecules. To be able to precisely determine sensed molecular concentrations and carry out precise analyses of single-molecule binding/unbinding events in real time it is necessary to quantify rigorously the relation between the number of b...
We introduce a novel optical biosensing platform that exploits the asymmetry of embedded nanostructures, termed nanomenhirs. Upon oblique illumination using plane polarized white light, two plasmonic resonances attributable to the bases and the axes of the nanomenhirs emerge; these are used for location-specific sensing of membrane-binding events....
Optical biosensors based on surface plasmon resonance (SPR) in metallic thin films are currently standard tools for measuring molecular binding kinetics and affinities - an important task for biophysical studies and pharmaceutical development. Motivated by recent progress in the design and fabrication of metallic nanostructures, such as nanoparticl...
Simultaneous LSPR and electronic sensing of potential induced ion adsorption onto gold nanowire arrays is presented. The formation of a Stern layer upon applying an electrochemical potential generated a complex optical response. Simulation of a lossy atomic layer on the nanowire array using the Multiple Multipole Program (MMP) corresponded very wel...
Nanoholes with short-range ordering were fabricated in ultrathin aluminum/aluminum nitride multilayer films where each layer is as thin as a few nanometers. Optical resonances of the trilayer system with a single metallic layer and five-layer system with two metallic layers were successfully tuned in the visible-near-infrared (vis/NIR) range. The r...
This consistent and systematic review of recent advances in optical antenna theory and practice brings together leading experts in the fields of electrical engineering, nano-optics and nano-photonics, physical chemistry and nanofabrication. Fundamental concepts and functionalities relevant to optical antennas are explained, together with key princi...
There is no doubt that the recent advances in nanotechnology have made it possible to realize a great variety of new sensors with signal transduction mechanisms utilizing physical phenomena at the nanoscale. Some examples are conductivity measurements in nanowires, deflection of cantilevers and spectroscopy of plasmonic nanoparticles. The fact that...
We present the fabrication and optical characterization of plasmonic nanostructures consisting of nanohole arrays in two thin films, a metal and a dielectric. A novel method called mask-on-metal colloidal lithography is used to prepare high aspect ratio holes, providing efficient mass fabrication of stable structures with close to vertical walls an...
This chapter aims to give an overview of how to optimize the performance of nanoplasmonic sensors. Specific biosensing challenges beyond the capability of current nanoplasmonic sensors will be discussed. Various methods to improve sensor performance will then be introduced, including solving issues related to surface chemistry. We distinguish the c...
This chapter is dedicated to nanoplasmonic sensing systems made compatible with studies of artificial cell membranes. After a short motivation to the opportunity of sensors designed for such studies to fill an existing technological gap, we introduce basic features of cell membranes and common mimics of the cell membrane that have been proven usefu...
Many nanotechnological devices are based on implementing electrochemistry with plasmonic nanostructures, but these systems are challenging to understand. We present a detailed study of the influence of electrochemical potentials on plasmon resonances, in the absence of surface coatings and redox active molecules, by synchronized voltammetry and spe...
The book presents an integrated view of plasmonic biosensors that operate by refractometric detection. This means that analyte binding to the sensor surface induces a local change in refractive index, which alters the far field spectrum, as detected by optical spectroscopy. Other plasmonic biosensors such as those based on coupling between suspende...
The enormous progress of nanotechnology during the last decade has made it possible to fabricate a great variety of nanostructures. On the nanoscale, metals exhibit special electrical and optical properties, which can be utilized for novel applications. In particular, plasmonic sensors including both the established technique of surface plasmon res...
Biosensing with nanoholes is one of the most promising applications of nanoplasmonic devices. The sensor properties, however, are complex due to coupled resonances through propagating and localized surface plasmons. This Full Paper demonstrates experimental and simulation studies on different plasmonic hole systems, namely various patterns of circu...
We show how gold recrystallizes when under the influence of electrochemical potentials. This "cold annealing" occurs without charge transfer reactions and preserves nanoscale structural features. By performing the process on plasmonic nanostructures, grain growth is monitored noninvasively by optical spectroscopy. In this way, the influence from cr...
Nanoplasmonic sensors based on short-range ordered nanoholes in thin metal films and discrete metal nanoparticles are known to provide similar sensing performance. However, a perforated metal film is unique in the sense that the holes can be designed to penetrate through the substrate, thereby also fulfilling the role of nanofluidic channels. This...
The optical signal of a localized surface plasmon resonance (LSPR)-based sensor combined with electrochemistry was investigated. Gold nanoparticles were immobilized on an indium tin oxide (ITO) substrate, which functioned as working electrode. Using cyclic voltammetry synchronized with LSPR sensing, surface reactions on gold were detected both elec...