Gold Nanostars in Biology and Medicine: Understanding Physicochemical Properties to Broaden Applicability

Abstract

Over the past few years, gold nanostars have gained significant relevance in biology and medicine, in particular, in imaging and photothermal therapy, also owing to their biocompatibility. Furthermore, they have improved the sensitivity of diagnostic assays and have been integrated in lab-on-chip platforms for low-cost, field-deployable devices. However, despite their widespread use, they have not found applicability beyond the research laboratories. One of the main reasons for this limitation has been the almost exclusive focus, until recently, on applications alone and not on the understanding of the fundamental properties of these particles, which has hampered reproducibility, stability, and overall reliability. Recently, however, a resurgence in the fundamental research of gold nanostars has dramatically improved our understanding of their synthesis, functionalization, properties, and thus their applicability. In this Perspective, the literature exploring and improving our knowledge of the physicochemical properties of gold nanostars is critically presented and framed within the specific context of biological and clinical applications. Furthermore, on the basis of the most recently reported results, a path forward is proposed, aimed at enabling an effective integration of these particles in the clinic.

Modeling of Laser-Induced Plasmon Effects in GNS-DLC-Based Material for Application in X-ray Source Array Sensors

“…It is characteristic that the spectral curves Q for each of the points are predominantly single-peaked. [18][19][20]. Note that despite the symmetric position of points 1 and 6 with respect to the electric vector of the irradiating field, the ratio ψ = |Enormal| 2 /|E0| 2 for them differs by a factor of five.…”

“…Figure 8 a shows the spectral dependences of the square of the modulus of the normal component | E normal |, normalized to the square of the modulus of the irradiating field strength | E 0 | and proportional to the concentration of hot electrons [ 18 , 19 , 20 ]. Note that despite the symmetric position of points 1 and 6 with respect to the electric vector of the irradiating field, the ratio ψ = | E normal | 2 /| E 0 | 2 for them differs by a factor of five.…”

“…Plasmon-resonant GNS are of particular interest as a new type of metal nanoparticles used in various technical and biomedical applications [ 19 , 20 , 21 , 22 , 29 , 30 , 31 , 32 , 33 ]. Compared to nanospheres, the advantage of their use is high absorption of radiation in the NIR (which is important, in particular, for laser medicine and biophotonics, including biosensing, optoporation, and the transfection of cells [ 19 , 29 ]. Compared to nanorods, GNS are characterized by a lower orientational and polarization sensitivity of induced optical [ 33 , 34 , 35 ] and temperature [ 36 ] fields.…”

“…We propose to use the phenomenon of localized surface plasmon resonance (LSPR) of metal nanoparticles, which has become widespread in numerous biomedical applications related to imaging, therapy, and diagnostics [ 19 ]. The main manifestation of LSPR is the resonant absorption of the irradiating optical field caused by collective oscillations of equilibrium (Drude electrons) and nonequilibrium (hot) electrons.…”

Gold Nanostars Bioconjugation for Selective Targeting and SERS Detection of Biofluids

“…Moreover, the introduction of different moieties on the surface of NPs combines the interesting plasmonic properties with the selective and specific recognition capabilities of the Ab towards antigens [ 2 ]. Thus, it becomes straightforward the possibility to achieve reliable and reproducible methods of conjugation to develop platforms for next generation technologies ranging from diagnostics to therapeutics [ 3 ]. The two main strategies applied for the conjugation of antibodies to AuNPs are (i) physisorption and (ii) chemisorption [ 4 ].…”