Gold nanostars with tuneable optical properties are synthesized via a seed-mediated approach employing adenosine monophosphate (AMP) as a capping ligand. AMP directs the reduction of the gold salt and mediates the anisotropic nanoparticle growth.

In the present work, the synthesis and characterization of silver triangular nanoplates (AgNTs) and their silica coating composites are reported. Engineering control on the surface coating has demonstrated the possibility to modulate the antibacterial effect. Several AgNT-coated nanomaterials, such as PVP (Polyvinylpyrrolidone) and MHA (16-mercaptohexadecanoic acid) as a stable organic coating system as well as uniform silica coating (≈5 nm) of AgNTs, have been prepared and fully characterized. The antibacterial properties of the systems reported, organic (MHA) and inorganic (amine and carboxylic terminated SiO₂) coating nanocomposites, have been tested on Gram-positive and Gram-negative bacteria strains. We observed that the AgNTs' organic coating improved antimicrobial properties when compared to other spherical silver colloids found in the literature. We have also found that thick inorganic silica coating decreases the antimicrobial effect, but does not cancel it. In addition, the effect of surface charge in AgNTs@Si seems to play a crucial role toward S. aureus ATCC 25923 bacteria, obtaining MIC/MBC values compared to the AgNTs with an organic coating.

Polymer nanoparticles doped with fluorescent molecules are widely applied for biological assays, local temperature measurements, and other bioimaging applications, overcoming several critical drawbacks, such as dye toxicity, increased water solubility, and allowing imaging of dyes/drug delivery in water. In this work, some polymethylmethacrylate (PMMA), polyvinylpyrrolidone (PVP) and poly(styrene-butadiene-styrene) (SBS) based micro and nanoparticles with an average size of about 200 nm and encapsulating B(III) compounds have been prepared via the reprecipitation method by using tetrahydrofuran as the oil phase and water. The compounds are highly hydrophobic, but their encapsulation into a polymer matrix allows obtaining stable colloidal dispersions in water (3.39 µM) that maintain the photophysical behavior of these dyes. Although thermally activated non-radiative processes occur by increasing temperature from 25 to 80 °C, the colloidal suspension of the B(III) particles continues to emit greenish light (λ = 509 nm) at high temperatures. When samples are cooling back to room temperature, the emission is restored, being reversible. A probe of concept drug delivery study was conducted using coumarin 6 as a prototype of a hydrophobic drug.

Colloidal chiral plasmonic nanoparticles are garnering growing interest due to their interaction with circularly polarized light, offering advanced optical applications. Their circular dichroism (CD) spectra are significantly narrower and more defined than extinction spectra, making them ideal for refractive index‐based sensing. Despite progress in colloidal synthesis, this field remains relatively underexplored. In this work, a one‐step, seed‐mediated route to chiral Au nanorods is introduced in which the molar ratio Au ³ ⁺/Au⁰ enables continuous control of the CD response (intensity, sign, and position), using L‐ and D‐cysteine as chiral inducers. CD‐based refractive index sensitivity (RIS) measurements reveal a figure of merit (FoM = RIS/linewidth) exceeding 1000 RIU ⁻¹ , outperforming the conventional extinction‐based approaches. Thin films of C‐AuNRs fabricated via a layer‐by‐layer assembly retain the bisignate CD response and show RIS values comparable to colloidal samples. These films demonstrate excellent stability, reusability, and resilience in highly absorbing media. All the experimental data are supported by advanced calculations performed using full‐wave M3 Maxwell's solver and using electron tomography reconstructions as direct input. Finally, their applicability in RI‐based quantitative detection of bovine serum albumin (BSA) is demonstrated, highlighting their potential for biomolecular sensing.

In this study, we propose a novel approach for the silica coating of silver nanoparticles based on surface modification with adenosine monophosphate (AMP). Upon AMP stabilization, the nanoparticles can be transferred into 2-propanol, promoting the growth of silica on the particle surfaces through the standard Stöber process. The obtained silica shells are uniform and homogeneous, and the method allows a high degree of control over shell thickness while minimizing the presence of uncoated NPs or the negligible presence of core-free silica NPs. In addition, AMP-functionalized AgNPs could be also coated with a mesoporous silica coating using cetyltrimethylammonium chloride (CTAC) as a template. Interestingly, the thickness of the mesoporous silica coating could be tightly adjusted by either the silica precursor concentration or varying the CTAC concentration while keeping constant the silica precursor concentration. Finally, the influence of the silica coating on the antimicrobial effect of AgNPs was studied on gram-negative bacteria (R. gelatinous and E. coli) and under different bacterial growth conditions, shedding light on their potential applications in different biological environments.

We present a seed-mediated approach for producing silver nanoplates with customizable size and thickness, offering high yield and precise optical properties. Leveraging ethylenediaminetetraacetic acid (EDTA) in the seed-mediated synthesis, we employ small single-crystal silver seeds as a foundation. The interaction between Ag+ and EDTA at different pHs dynamically controls silver complexation/reduction kinetics during seed overgrowth, yielding truncated nanoplates with superior optical responses. The pH adjustment within the range of 8 to 10.5 enables manipulation of nanoplate growth, resulting in a flexible optical response spanning 519 to 1006 nm associated with morphological changes (size and thickness). Additionally, nanoplate overgrowth extends plasmon resonance up to ca. 2000 nm. Notably, the incorporation of Adenosine 5’-monophosphate (AMP) enhances nanoplate stability and more important, enables precise thickness adjustment, independent of growth kinetics. Our method offers a systematic approach to tailor nanoplate morphology and optical properties with unprecedented precision.