Marek Grzelczak

Donostia International Physics Center | DIPC

Periodic responses to non-periodic energy inputs are hallmarks of living systems, that lead to metastable features across length scales, exemplified by phenomena such as oscillations. Experimental attempts to mimic such phenomenon have primarily utilized (macro)molecular building blocks that enable precise control over interactions and thus hierarc...

Proper formulation of systems containing plasmonic and photochromic units, such as gold nanoparticles and azobenzene derivatives, yields materials and interfaces with synergic functionalities. Moreover, gold nanoparticles are known to accelerate the Z-E isomerization of azobenzene molecules in the dark. However, very little is known about the light...

Unraveling the nuanced interplay between the morphology and the optical properties of plasmonic nanoparticles is crucial for targeted applications. Managing the relationship becomes significantly complex when dealing with anisotropic nanoparticles that defy a simple description using parameters like length, width, or aspect ratio. This complexity r...

Liquid-phase transmission electron microscopy is a burgeoning experimental technique for monitoring nanoscale dynamics in a liquid environment, increasingly employing microfluidic reactors to control the composition of the sample solution. Current challenges comprise fast mass transport dynamics inside the central nanochannel of the liquid cell, ty...

In diverse fields, machine learning (ML) has sparked transformative changes, primarily driven by the wealth of big data. However, an alternative approach seeks to mine insights from “precious data”, offering the possibility to reveal missed knowledge and escape potential knowledge traps. In this context, Bayesian optimization (BO) protocols have em...

The field of quantum technology has been rapidly expanding in the past decades, yielding numerous applications, such as quantum information, quantum communication, and quantum cybersecurity. At the core of these applications lies the quantum emitter (QE), a precisely controllable generator of either single photons or photon pairs. Semiconductor QEs...

Plexcitonic systems based on metal nanostructures and molecular J-aggregates offer an excellent opportunity to explore the intriguing interplay between plasmonic excitations and excitons, offering unique insights into light–matter interactions at the nanoscale. Their potential applications in photocatalysis have prompted a growing interest in both...

Temperature‐modulated colloidal phase of plasmonic nanoparticles is a convenient playground for resettable soft‐actuators or colorimetric sensors. To render reversible clustering under temperature change, bulky ligands are required, especially if anisotropic morphologies are of interest. This study showcases thermoresponsive gold nanorods by employ...

In principle, designing and synthesizing almost any class of colloidal crystal is possible. Nonetheless, the deliberate and rational formation of colloidal quasicrystals has been difficult to achieve. Here we describe the assembly of colloidal quasicrystals by exploiting the geometry of nanoscale decahedra and the programmable bonding characteristi...

Self oscillation ‐ the periodic change of a system under a non‐periodic stimulus ‐ is vital for creating low‐maintenance autonomous devices in soft robotics technologies. Soft composites of macroscopic dimensions are often doped with plasmonic nanoparticles to enhance energy dissipation and generate periodic response. However, while it is still unk...

The field of quantum technology has been rapidly expanding in the past decades, yielding numerous applications as quantum information, quantum communication and quantum cybersecurity. The central building block for these applications is a quantum emitter (QE), a controllable source of single photons or photon pairs. Semiconductor QEs such as perovs...

Liquid Phase-Transmission Electron Microscopy research increasingly relies on liquid flow reactors to monitor nanoscale dynamics. Current challenges comprise fast mass transport dynamics inside the central nanochannel of the liquid cell, typically flow cells , and reliable fixation of the specimen in the limited imaging area. In this work, we prese...

Spurred by outstanding optical properties, chemical stability, and facile bioconjugation, plasmonic metals have become the first-choice materials for optical signal transducers in biosensing. While the design rules for surface-based plasmonic sensors are well-established and commercialized, there is limited knowledge of the design of sensors based...

Spurred by outstanding optical properties, chemical stability, and facile bioconjugation, plasmonic metals have become the first-choice materials for optical signal transducers in biosensing. While the design rules for surface-based plasmonic sensors are well-established and commercialized, there is limited knowledge of the design of sensors based...

Even with the widespread uptake of vaccines, the SARS-CoV-2-induced COVID-19 pandemic continues to overwhelm many healthcare systems worldwide. Consequently, massive scale molecular diagnostic testing remains a key strategy to control the ongoing pandemic, and the need for instrument-free, economic and easy-to-use molecular diagnostic alternatives...

Stimuli‐responsive, optically‐active colloidal systems are convenient signal transducers capable of monitoring environmental changes at the nanoscale. We report on the coupling of chemo‐thermal cycloaddition reaction with temperature‐sensitive, DNA‐coated gold nanoparticles. We found that the concentration of chemical fuel, dictating the temperatur...

Liquid-Phase Transmission Electron Microscopy (LP-TEM) offers the opportunity to study nanoscale dynamics of phenomena related to materials and life science in a native liquid environment and in real time. Until now, the opportunity to control/induce such dynamics by changing the chemical environment in the liquid flow cell (LFC) has rarely been ex...

The development of plasmonic nanomaterials with chiral geometry has drawn extensive attention owing to their practical implications in chiral catalysis, chiral metamaterials, or enantioselective biosensing and medicine. However, due to the lack of effective synthesis methods of hydrophobic nanoparticles (NPs) showing intrinsic, plasmonic chirality,...

The coherence length of the Frenkel excitons (Ncoh) is one of the most critical parameters governing many key features of supramolecular J-aggregates. Determining experimentally the value of Ncoh is a nontrivial task since it is sensitive to the technique/method applied, causing discrepancies in the literature data even for the same chemical compou...

A statistical thermodynamics variational criterion is propounded to study thermal hysteresis in reversible clustering of gold (Au) nanoparticles. Experimentally, a transient equilibrium mapping analysis is employed to characterize it thermodynamically, further measurements being performed at the nanostructural and electrochemical levels (UV-Vis-NIR...

Plasmonic catalysis in the colloidal phase requires robust surface ligands that prevent particles from aggregation in adverse chemical environments and allow carrier flow from reagents to nanoparticles. This work describes the use of a water-soluble conjugated polymer comprising a thiophene moiety as a surface ligand for gold nanoparticles to creat...

Strong exciton–plasmon interaction enables effective control of the photonic properties of hybrid organic–inorganic nanostructures encompassing light absorption, scattering and luminescence. Whereas the manifestations of light-matter interactions in the absorption and scattering are reasonably well understood their relation to the luminescence as w...

In a typical colloidal synthesis, the molecules of the reducing agent are irreversibly oxidized during nanocrystal growth. Such a scenario is of questionable sustainability when confronted with naturally occurring processes in which reducing agent molecules are cyclically regenerated. Here we show that cofactor molecules once consumed in the nuclea...

The colloidal stability of metal nanoparticles is tremendously dependent on the thermal behavior of polymer brushes. Neat polyethylene glycol (PEG) presents an unconventional upper critical solution temperature in ethanol, where phase segregation and crystallization coexist. This thermal behavior translated to a PEG brush has serious consequences o...

Excitons in semiconductor quantum dots (QDs) feature high values of the two-photon absorption cross-sections (TPACSs), enabling applications of two-photon-excited photoluminescence (TPE PL) of QDs in biosensing and nonlinear optoelectronics. However, efficient TPE PL of QDs requires high-intensity laser fields, which limits these applications. Ther...

Cyclic polymers behave different than linear polymers due to the lack of end groups and smaller coil dimensions. Herein, we demonstrate that cyclic polyethylene glycol (PEG) can be used as an alternative of classical linear PEG ligands for gold nanoparticle (AuNP) stabilization. We observed that the brush height of cyclic PEG on AuNPs of diameter 4...

Hysteresis is an essential attribute of many solid-state devices and biological processes, yet it is often overlooked in colloidal and soft-matter dynamic systems. Herein, we show that gold nanoparticles can remain dispersed or aggregated at the same temperature depending on the trajectory of applied stimulus, featuring hysteretic behavior. Aided b...

Hybridized plexcitonic states have unique properties which have been widely studied in recent decades in many research fields targeted at both fundamental science and innovative applications. However, to make these applications come true one needs to ensure the stabilization and preservation of electronic states and optical transitions in hybrid na...

Hysteresis is an essential attribute of many solid-state devices and biological processes, yet it is often overlooked in colloidal and soft-matter dynamic systems. Herein we show that gold nanoparticles can remain dispersed or aggregated at the same temperature depending on the trajectory of applied stimulus, featuring hysteretic behaviour. Aided b...

We present an electromagnetic analogue of crystal (or ligand) field theory that describes geometric eigenmodes and the resonant plasmon wavelength in plasmonic nanocrystals in terms of a simple shape descriptor. Our model - crystal field plasmon splitting - is based on secular equations for geometric eigenmodes, allowing for the separation of pure...

Plasmonic nanoparticles exhibit excellent light-harvesting properties in the visible spectral range, which makes them convenient material for the conversion of light into useful chemical fuel. However, the need for using surface ligands to ensure colloidal stability of nanoparticles inhibits their photochemical performance, due to the insulating mo...

The possibility of detecting genetic mutations rapidly in physiological media through liquid biopsy has attracted the attention within the materials science community. The physical properties of nanoparticles combined with robust transduction methods ensure an improved sensitivity and specificity of a given assay and its implementation into point-o...

A smooth sphere-to-cube transition is experimentally, computationally and theoretically studied in plasmonic Au nanoparticles, including retardation effects. Localized surface plasmon-polariton resonances were described with precision, discriminating among the influences of shape statistics, particle polydispersity, electrochemistry of excess (surf...

The release of bioactive Strontium ions (Sr²⁺) from titanium implants has a positive impact on osseointegration. It is however challenging to achieve a slow Sr²⁺ release over weeks until tissue regeneration. A hybrid mesoporous titania film (MTF) displaying carboxylic moieties in pore walls has been developed here for encapsulation and slow deliver...

Gold and silver nanoclusters aggregates have gained significant attention as their optical properties and chemical stability surpasses those of individual nanoclusters. Here, we present a systematic investigation of aggregation-induced changes of morphology and optical properties of glutathione-stabilized silver-doped gold nanoclusters (AuAg NCs)....

We introduce an approach to synthesize macrocyclic poly(ethylene oxide)s containing a pendant protected thiol group (pSH-CPEO), which is demonstrated to be able to attach to gold surfaces without prior deprotection. Our strategy is based on a bimolecular approach by which a di-alkyne molecule derived from thiol-protected 3-mercapto-1,2-propanediol...

Antibacterial coatings are prepared by self‐assembly of gentamicin polyacrylic acid complexes in layer‐by‐layer films. The coatings release gentamicin over several weeks, preventing the growth of S. aureus strains, and have potential applications for surface modification of titania implants to prevent nosocomial infections, which are a major concer...

The interaction of several components in the strong coupling regime yielding multiple Rabi splittings opens up remarkable possibilities for studies of multimode hybridization and energy transfer, which is of considerable interest in both fundamental and applied science. Here we demonstrate that three different components such as core-shell [email p...

There is an urgent need for the development of effective antibacterial coatings to cope with more and more resistant bacterial strains in medical environments, and particularly to prevent nosocomial infections following bone implant surgery. Polyelectrolyte multilayers (PEMs) based on poly‐l‐lysine (PLL) and complexes of poly(acrylic acid) (PAA) an...

For decades, plasmonic nanoparticles have been extensively studied due to their extraordinary properties, related to localized surface plasmon resonances. A milestone in the field has been the development of the so-called seed-mediated growth method, a synthetic route that provided access to an extraordinary diversity of metal nanoparticles with ta...

The incorporation of strontium (Sr) in titania enhances surface bioactivity and has a positive effect on pre‐osteoblastic cell attachment, proliferation, and differentiation. Strontium titanate mesoporous films (SrTiMFs) with 30% pore volume and a 20% Sr molar content have been prepared by the evaporation induced self‐assembly method. SrTiMFs displ...

The hydrophobic collapse is a structural transition of grafted polymer chains in a poor solvent. Although such a transition seems an intrinsic event during clustering of polymer-stabilized nanoparticles in the liquid phase, it has not been resolved in real time. In this work, we implemented a microfluidic 3D-flow-focusing mixing reactor equipped wi...

Mesoporous Titania Films (MTFs) are synthesized through the sol‐gel technique for gentamicin loading and delivery, and the functionalization of the MTFs surface with human recombinant bone morphogenetic protein 2. This doubly functionalized MTFs have been shown to be effective against S. aureus colonization and the presence of hrBMP‐2 enhances MC3T...

The capacity to respond or adapt to environmental changes is an intrinsic property of living systems that comprise highly-connected subcomponents communicating through chemical networks. The development of responsive synthetic systems is a relatively new research area that covers different disciplines, among which nanochemistry brings conceptually...

Novel approaches are needed to avoid bacterial infections following implant surgery. Here the use of mesoporous titania films (MTFs) for gentamicin loading and delivery and the surface functionalization of MFTs with human recombinant bone morphogenetic protein 2 (hrBMP‐2) are discussed. Gentamicin is incorporated into the MTF pores by immersion of...

Semiconductor quantum dots (QDs) are known for their ability to multiphoton emission caused by recombination of biexcitons (BX). However, the quantum yield (QY) of BX emission is low due to the fast Auger process. Plasmonic nanoparticles (PNPs) provide an attractive opportunity to accelerate the BX radiative recombination. Here, we demonstrate the...

NMR-based techniques are supposed to be incapable of distinguishing pure crystalline chemical enantiomers. However, through systematic studies of cross-polarization magic angle spinning (CP-MAS) NMR in ‎a series of aminoacids, we have found a rather unexpected behavior in the intensity pattern of optical isomers in hydrogen/nitrogen nuclear polariz...

Development of synthetic systems carrying life-like features is a long-standing challenge in chemistry and material science. Poor understanding of mechanisms ruling the emergence of life-like features in an inanimate matter makes the challenge even more exciting. The growing field of systems chemistry takes the lead in defining life-like dynamic si...

Triethanolamine is a widely used model electron donor that enables a fast screening of the photocatalyst parameters in both, homogeneous and heterogeneous scenarios. We report a new role of triethanolamine in heterogeneous photoregeneration of cofactor molecules – nicotinamide adenine dinucleotide (NADH) – using state-of-the-art heterogeneous photo...

The use of gold nanoparticles for the colorimetric detection of single nucleotide mutations associated with cancer in liquid biopsies is a promising strategy for early cancer diagnosis. In order to realize this technology, the sensor must discriminate mutations in double stranded (ds)DNA with an average length of ~140 bp. Here we compared ssDNA and...

The presence of iodide ions during the growth of gold nanorods strongly affects the shape of the final products, which is proposed to be due to selective iodide adsorption on certain crystallographic facets. Therefore, a detailed structural and morphological characterization of the starting rods is crucial toward understanding this effect. Electron...

A limiting factor of solvent-induced self-assembly of nanoparticles is the need for constant sample dilution in assembly/disassembly cycles. Changes in nanoparticle concentration alter the kinetics of the subsequent assembly process, limiting optical signal recovery. Here we show that by confining hydrophobic nanoparticles in permeable silica nanoc...

A limiting factor of solvent-induced self-assembly of nanoparticles is the need for constant sample dilution in assembly/disassembly cycles. Changes in nanoparticle concentration alter the kinetics of the subsequent assembly process, limiting optical signal recovery. Here we show that by confining hydrophobic nanoparticles in permeable silica nanoc...

Three dimensional (3D) characterization of structural defects in nanoparticles by transmission electron microscopy is far from straightforward. We propose the use of a dose-efficient approach, so-called multimode tomography, during which tilt series of low and high angle annular dark field scanning transmission electron microscopy projection images...

In a photobiocatalytic process involving water oxidation and simultaneous organic molecules reduction (e.g., cofactors), the lack of physical separation of redox half-reactions adversely affects the product stability. Surface co-catalysts, in general, improve the selectivity of the photocatalyst toward water oxidation, but harsh oxidative environme...

Developing strategies to detect single nucleotide DNA mutations associated with treatment decisions in cancer patients from liquid biopsies is a rapidly emerging area of personalized medicine that requires high specificity. Here we report how to design an easy enzyme-free approach that could create a platform for detection of L858R mutation of EGFR...

Inorganic–organic hybrid mesoporous silica thin films with covalently bonded carboxylic acid groups were synthesized in a one-step procedure, using carboxylic-derivatized alkoxysilanes obtained by photochemical radical thiol-ene addition (PRTEA). The organosilanes were synthesized by clicking mercaptosuccinic or mercaptoacetic thioacids with vinylt...

Single-nanoparticle imaging and theoretical modeling can guide synthesis strategies

Circulating DNA (ctDNA) and specifically the detection cancer-associated mutations in liquid biopsies promises to revolutionize cancer detection. The main difficulty however is that the length of typical ctDNA fragments (~150 bases) can form secondary structures potentially obscuring the mutated fragment from detection. We show that an assay based...

Plasmonic nanoparticles (PNPs) can significantly modify the optical properties of nearby organic molecules and thus present an attractive opportunity for sensing applications. However, the utilization of PNPs in conventional absorption, fluorescence or Raman spectroscopy techniques is often ineffective due to strong absorption background and light...

We show that thermal treatment of small Au seeds results in extensive twinning and a subsequent drastic improvement in the yield (>85%) of formation of pentatwinned nanoparticles (NPs), with preselected morphology (nanorods, bipyramids, and decahedra) and aspect ratio. The “quality” of the seeds thus defines the yield of the obtained NPs, which in...

Detection of single nucleotide polymorphisms (SNP) by selective aggregation of nanoparticles offers a rapid determination of cancer biomarkers, detectable by the naked eye. The main factor limiting the sensitivity of such colloidal sensors is the number of available target DNA molecules that can induce aggregation and thereby transduce an optical o...

It is commonly agreed that the crystalline structure of seeds dictates the crystallinity of final nanoparticles in a seeded-growth process. Although the formation of monocrystalline particles does require the use of single-crystal seeds, twin planes may stem from either single- or polycrystalline seeds. However, experimental control over twin-plane...

Strong coupling of plasmons and excitons can form hybrid states, the so-called “plexcitons”. Although plasmons have a low quality factor, the exceptional high coupling strength with molecular aggregates, in particular J-aggregates, allows the realization of strong interaction. Despite several studies in recent years showing the formation of plexcit...

Metal nanoparticles with a dumbbell-like geometry have similar plasmonic properties as their nanorod counterparts, but the unique steric constraints induced by their enlarged tips result in distinct geometries when self-assembled. Here we investigate gold dumbbells that are assembled into dimers within polymeric micelles. A single particle approach...

Because the ultimate target for photothermal therapy is the cancer cell, heating performances must be evaluated intracellularly. On page 1040 C. Wilhelm and team provide the first in vitro and in vivo photothermal measurements in cancer cells with gold nanostars. They demonstrate that once nanostars are internalized within endosomes, heat generatio...

The light harvesting capacity of plasmonic nanoparticles is a fundamental feature for catalysing chemical reactions close to their surface. The efficiency of the photochemical processes depends not only on the geometrical aspects on a single particle level but also on the complexity of the multiparticle architectures. Although, the effect of the pa...

Gold nanoparticles are prime candidates for cancer thermotherapy. However, while the ultimate target for nanoparticle-mediated photothermal therapy is the cancer cell, heating performance has not previously been evaluated in the tumoral environment. A systematic investigation of gold nanostar heat-generating efficiency in situ is presented: not onl...

We experimentally and theoretically investigate the interactions between localized plasmons in gold nanorods and excitons in J-aggregates at ambient conditions. Thanks to our sample preparation procedure we were able to track a clear anti-crossing behavior of the hybridized modes not only in the extinction but also, to our knowledge for the first t...

We present our recent results on the development and characterization of hybrid sytems consisting of plasmonic nanostructures and organic dye molecules in a J-aggregate state. The measured spectra exhibit a strongly suppressed signal at wavelengths which correspond to the J-aggregate band, which is indicative of strong interaction between the plasm...

The remote release of nano-objects from a container is a promising approach to transduce chemical events into an optical signal. The major challenge in the development of such a system involves the use of a suitable molecular gate that retains aggregated particles and releases them upon applying an external stimulus. We show proof-of-concept experi...

Gold nanorods have numerous applications in biomedical research, including diagnostics, bioimaging and photothermal therapy. Even though surfactant removal and surface conjugation with anti-fouling molecules such as polyethylene glycol (PEG) are required to minimize non-specific protein binding and cell uptake, the reliable characterization of thes...

We present a simple method for the co-encapsulation of gold nanostars and iron-oxide nanoparticles into hybrid colloidal composites that are highly responsive to both light and external magnetic fields. Self-assembly was driven by hydrophobic interactions between polystyrene capped gold nanostars and iron oxide nanocrystals stabilized with oleic ac...

Poly(ethylene glycol) (PEG) has become the gold standard for stabilization of plasmonic nanoparticles in biofluids, because it prevents aggregation while minimizing unspecific interactions with proteins. Application of gold nanoparticles in biological environments requires the use of ligands that can target selected receptors, even in the presence...