Plasmon-enhanced photocatalysis: New horizons in carbon dioxide reduction technologies.

The urgent need for transition to renewable energy is underscored by a nearly 50 % increase in atmospheric carbon dioxide levels over the past century. The combustion of fossil fuels for energy production, transportation, and industrial activities are the main contributors to carbon dioxide emissions in the anthroposphere. Present approaches to reducing carbon emissions are proving inefficient, thereby accentuating the relevance of carbon dioxide photocatalysis in combating climate change - one of the critical issues of public concern. This process uses sunlight to convert carbon dioxide into valuable products, e.g., clean fuels, effectively reducing the carbon footprint and offering a sustainable use of carbon dioxide. In this context, plasmonic nanoparticles such as gold, silver, and copper play a pivotal role due to their proficiency in absorbing a wide range of light spectra, thereby effectively generating the necessary electrons and holes for the degradation of pollutants and surpassing the capabilities of traditional semiconductor catalysts. This review meticulously examines the latest advancements in plasmon-based carbon dioxide photocatalysis, scrutinizing the methodologies, characterizations, and experimental outcomes. The critical evaluation extends to exploring adjustments in the dimensional and morphological aspects of plasmonic nanoparticles, complemented by the incorporation of stabilizing agents, which may offer additional benefits. Furthermore, the review includes a thorough analysis of production rates and quantum yields based on different plasmonic materials and nanoparticle shapes and sizes, enriching the ongoing discourse on effective solutions in the field. Thus, our work emphasizes the pivotal role of plasmon-based photocatalysts in reducing carbon dioxide, investigating both the merits and challenges associated with integrating this emerging technology into climate change mitigation efforts.

Portable microfluidic plasmonic chip for fast real-time cardiac troponin I biomarker thermoplasmonic detection.

Acute myocardial infarction is one of the most serious cardiovascular pathologies, impacting patients' long-term outcomes and health systems worldwide. Significant effort is directed toward the development of biosensing technologies, which are able to efficiently and accurately detect an early rise of cardiac troponin levels, the gold standard in detecting myocardial injury. In this context, this work aims to develop a microfluidic plasmonic chip for the fast and accurate real-time detection of the cardiac troponin I biomarker (cTnI) via three complementary detection techniques using portable equipment. Furthermore, the study focuses on providing a better understanding of the thermoplasmonic biosensing mechanism taking advantage of the intrinsic photothermal properties of gold nanoparticles. Specifically, a plasmonic nanoplatform based on immobilized gold nanobipyramids was fabricated, exhibiting optical and thermoplasmonic properties that promote, based on a sandwich-like immunoassay, the "proof-of-concept" multimodal detection of cTnI via localized surface plasmon resonance, surface enhanced Raman spectroscopy and thermoplasmonic effects under simulated conditions. Furthermore, after the integration of the plasmonic nanoplatform in a microfluidic channel, the determination of cTnI in 16 real plasma samples was successfully realized via thermoplasmonic detection. The results are compared with a conventional high-sensitivity enzyme-linked immunosorbent clinical assay (ELISA), showing high sensitivity (75%) and specificity (100%) as well as fast response features (5 minutes). Thus, the proposed portable and miniaturized microfluidic plasmonic chip is successfully validated for clinical applications and transferred to clinical settings for the early diagnosis of cardiac diseases, leading towards the progress of personalized medicine.

Anthracycline's Effects on Heart Rate Variability in Children with Acute Lymphoblastic Leukemia: Early Toxicity Signs-Pilot Study.

Anthracycline treatments are known to cause cardiotoxic long-term side effects in cancer survivors. Recently, a decrease in heart rate variability (HRV) has been identified in these patients, signaling autonomic dysfunction and altered cardiac fitness. This study aimed at evaluating changes in HRV in children treated with anthracyclines. A total of 35 pediatric patients with acute lymphoblastic leukemia were evaluated by means of a 24 h Holter ECG, at baseline and after reaching half the total cumulative dose of doxorubicin equivalent (120 mg/m2). Parameters of HRV were assessed, as well as any arrhythmic episodes, bradycardia and tachycardia percentages. The results showed a significant decrease in both time-domain and frequency-domain HRV parameters, following anthracycline treatment. The low-frequency (LF) to high-frequency (HF) parameters' ratio also displayed a significant difference (p = 0.035), suggestive of early cardiac autonomic dysfunction. Of note, none of the patients presented symptoms of heart disease or elevated troponins, and only two patients presented echocardiographic signs of diastolic dysfunction. The present study showed that cardiac autonomic nervous system regulation is compromised in children treated with anthracyclines even before reaching the total cumulative dose. Therefore, HRV parameters could be the first indicators of subclinical cardiac toxicity, making Holter ECG monitoring of the oncological patient a necessity.

Gelatin-assisted fabrication of reduced nanographene oxide for dual-modal imaging of melanoma cells.

In this work we report a gelatin-based, simple two-steps approach for fabrication of reduced graphene oxide (rGO-GEL) possessing high stability and biocompatibility, as novel label-free intracellular contrast agents. Gelatin, a biopolymer that is known for its versatility, was employed not only to biocompatibilize the rGO, but also to prevent the aggregation of the GO nanosheets during the reduction process. To confirm the successful reduction process and the attachment of the gelatin to the rGO nanosheets, we employed multiple spectroscopic analyses such as FT-IR, Raman, UV-VIS and photoluminescence, while the morphology and the lateral dimensions of the resulting hybrid rGO-GEL were investigated by Scanning-Transmission Electron Microscopy (STEM). Cellular toxicity test proved that the rGO-GEL nanoflakes are nontoxic for melanoma B16-F10 cells, even at high concentrations. Finally, the intracellular tracking after 24 h of treatment was performed by non-invasive Super-resolution re-scan confocal microscopy as well as Confocal Raman imaging, thus implementing our nanoflakes as a suitable contrast agent candidate for cellular imaging of interest.

Albumin nanoparticles with tunable ultraviolet-to-red autofluorescence for label-free cell imaging and selective biosensing of copper ion.

Early and simple detection of aberrant cooper metabolism in diseases with neurological-manifestations and several other conditions, including cancer, becomes an urgent necessity. Instrumental methods used today are limited to high-cost equipment and reagents and demand highly qualified personnel. In this work, we report easy-to-use and cost-effective nano-sized sensors for the selective and quantitative detection of copper ion based on fluorescence quenching. Glutaraldehyde cross-linked albumin nanoparticles with tunable ultraviolet-to-red autofluorescence emissions are developed as dual-agents for sensing and imaging. These albumin nanoparticles show great selectivity towards copper ion when tested against a selection of biochemical components and other metal ions, and a limit of detection as low as 1.9 µM, relevant for sensing in clinical diagnosis, was determined. In addition, a lack of toxicity and good cellular uptake were observed and the ultraviolet-to-red intrinsic fluorescence of the albumin nanoparticles was preserved when tested in vitro on NIH:OVCAR3 cell line. Preliminary studies confirm the albumin nanoparticles' ability to detect Cu2+in vitro and establishes their potential for future practical use.

NIR photothermal-activable drug-conjugated microcapsules for in vitro targeted delivery and release: An alternative treatment of diabetic retinopathy.

Diabetic retinopathy (DR) is one of the most serious complications of diabetes, which leads to blindness. By addressing the traditional treatment limitations, we developed a novel light-responsive targeted polymeric microcapsule able to encapsulate a near infrared (NIR) photoactive fluorophore - Indocyanine Green, owing to its photothermal properties. Moreover, for an efficient in vitro targeted drug delivery, the fluorescent microsystem was conjugated with a therapeutic agent, i.e., Avastin drug - a Food and Drug Administration approved therapeutic antibody. The microcapsules were fabricated and evaluated in terms of morphology, encapsulation and drug conjugation efficiency and its release capacity. Avastin-conjugated microcapsules with an average dimension of 4.5 ± 0.35 µm were obtained, according to Scanning Electron Microscopy and Re-Scanning Confocal Microscopy (RCM) investigations. The capacity of the microcapsules to operate as effective phototherapeutic agents by generating heat under NIR laser irradiation was evaluated, followed by the investigation of the microcapsule's shell rupture and NIR laser-induced release of Avastin. The biocompatibility of the Avastin-conjugated microcapsules was proven by WST-1 assay. In vitro cellular internalization and localization of the Avastin microcarriers were determined through Conventional fluorescence microscopy, RCM and Transmission Electron Microscopy imaging techniques. Finally, the Avastin-conjugated microcapsules were validated for in vitro targeted drug delivery and release directly under simulated DR conditions, which could certainly become a successful strategy in DR fighting.

Antibody-functionalized theranostic protein nanoparticles for the synergistic deep red fluorescence imaging and multimodal therapy of ovarian cancer.

Among women, ovarian cancer is the fifth most frequent type of cancer, and despite benefiting from current standard treatment plans, 90% of patients relapse in the subsequent 18 months and, eventually, perish. As a result, via embracing nanotechnological advancements in the field of medical science, researchers working in the areas of cancer therapy and imaging are looking for the next breakthrough treatment strategy to ensure lower cancer recurrence rates and improved outcomes for patients. Herein, we design a novel phototheranostic agent with optical features in the biological window of the electromagnetic spectrum via encapsulating a newly synthesized phthalocyanine dye within biocompatible protein nanoparticles, allowing the targeted fluorescence imaging and synergistic dual therapy of ovarian cancer. The nanosized agent displays great biocompatibility and enhanced aqueous biostability and photothermal activity, as well as high reactive-oxygen-species generation efficiency. To achieve the active targeting of the desired malignant tissue and suppress the rapid clearance of the photosensitive agent from the peritoneal cavity, the nanoparticles are biofunctionalized with an anti-folate receptor antibody. A2780 ovarian cancer cells are employed to confirm the improved targeting capabilities and the in vitro cytotoxic efficiency of the theranostic nanoparticles after exposure to a 660 nm LED lamp; upon measurement via MTT and flow cytometry assays, a significant 95% decrease in the total number of viable cells is seen. Additionally, the therapeutic performance of our newly designed nanoparticles was evaluated in vivo, via real-time thermal monitoring and histopathological assays, upon the irradiation of tumour-bearing mice with a 660 nm LED lamp (0.05 W cm-2). Foremost, separately from steady-state fluorescence imaging, we found that, via utilizing FLIM investigations, the differences in fluorescence lifetimes of antibody biofunctionalized and non-functionalized nanoparticles can be correlated to different intracellular localization and internalization pathways of the fluorescent agent, which is relevant for the development of a cutting-edge method for the detection of cancer cells that overexpress folate receptors at their surfaces.

Fluorescent Phthalocyanine-Encapsulated Bovine Serum Albumin Nanoparticles: Their Deployment as Therapeutic Agents in the NIR Region.

In recent times, researchers have aimed for new strategies to combat cancer by the implementation of nanotechnologies in biomedical applications. This work focuses on developing protein-based nanoparticles loaded with a newly synthesized NIR emitting and absorbing phthalocyanine dye, with photodynamic and photothermal properties. More precisely, we synthesized highly reproducible bovine serum albumin-based nanoparticles (75% particle yield) through a two-step protocol and successfully encapsulated the NIR active photosensitizer agent, achieving a good loading efficiency of 91%. Making use of molecular docking simulations, we confirm that the NIR photosensitizer is well protected within the nanoparticles, docked in site I of the albumin molecule. Encouraging results were obtained for our nanoparticles towards biomedical use, thanks to their negatively charged surface (-13.6 ± 0.5 mV) and hydrodynamic diameter (25.06 ± 0.62 nm), favorable for benefitting from the enhanced permeability and retention effect; moreover, the MTT viability assay upholds the good biocompatibility of our NIR active nanoparticles. Finally, upon irradiation with an NIR 785 nm laser, the dual phototherapeutic effect of our NIR fluorescent nanoparticles was highlighted by their excellent light-to-heat conversion performance (photothermal conversion efficiency 20%) and good photothermal and size stability, supporting their further implementation as fluorescent therapeutic agents in biomedical applications.

Prevalence of Underweight, Overweight and Obesity in School-Aged Children in the Urban Area of the Northwestern Part of Romania.

INTRODUCTION: During the last three decades, there has been an excess weight epidemic due to changes in nutrition and lifestyle. Few data on the prevalence of overweight and obesity in children in Romania were published, without a single study representative at the national level. There are reports on the higher level of overweight and obesity in urban areas compared to rural ones. This study aimed to estimate the prevalence of underweight, overweight, obesity and severe obesity in children enrolled in schools from the urban area. MATERIAL AND METHODS: For this cross-sectional study, children from 177 schools from the urban area of five counties from the northwestern part of Romania were included after the parents signed written informed consent. Anthropometric data were recorded (weight, height) based on World Health Organization (WHO) recommendations and Body-Mass-Index (BMI), and the z-score for BMI were calculated. The nutritional status was estimated using three reference criteria: WHO, International Obesity Task Force (IOTC) and the Center for Disease Control and Prevention (CDC). RESULTS: We analyzed data of 21,650 children (48.19% boys) age between 7 and 18 years. The prevalence of overweight was 13.8%, 16.2% and 20.3%, of obesity was 10.7%, 10.0% and 5.7% and of severe obesity was 5.1%, 1.2% and 1.6% (using WHO, CDC and IOTF cut-offs). Underweight was present in 5.2% (WHO), 6% (CDC) and 2.6% (IOTF). The highest prevalence of overweight (including obesity) was found in children aged 10 years, and the lowest in adolescents at 18 years. Boys have a higher prevalence of excess weight than girls. Using IOTF cut-offs, the prevalence of obesity and severe obesity was lower than using WHO criteria. CONCLUSIONS: The prevalence of overweight (including obesity) in children from the urban area of Western Romania was recorded at alarming levels, higher in boys and at the pre-puberty ages. There are significant differences based on the reference system used. It is important to correctly choose the reference for the definition of overweight and obesity to have the correct estimation of the target for public health measures.

Partnering bevacizumab with irinotecan as first line-therapy of metastatic colorectal cancer improves progression free survival-A retrospective analysis.

Colorectal cancer remains one of the most frequent malignancies (third place at both genders) worldwide in the last decade, owing to significant changes in modern dietary habits. Approximately half of the patients develop metastases during the course of their disease. The available therapeutic armamentarium is constantly evolving, raising questions regarding the best approach for improving survival. Bevacizumab remains one of the most widely used therapies for treating metastatic colorectal cancer and can be used after progression. This study aimed to identify the best chemotherapy partner for bevacizumab after progression. We performed a retrospective analysis of patients with metastatic colorectal cancer who were treated with bevacizumab as first- and second-line chemotherapy. Data were collected for 151 patients, 40 of whom were treated with double-dose bevacizumab after the first progression. The two standard chemotherapy regimens combined with bevacizumab were FOLFIRI/CAPIRI and FOLFOX4/CAPEOX. The initiation of first-line treatment with irinotecan-based chemotherapy improved progression-free survival and time to treatment failure but not overall survival. After the first progression, retreatment with the same regimen as that used in the induction phase was the best approach for improving overall survival (median overall survival: 46.5 vs. 27.0 months for the same vs. switched strategy, respectively). No correlations were observed between the dose intensity of irinotecan, oxaliplatin, 5-fluorouracil, or bevacizumab and the overall survival, progression-free survival in the first-/second-line treatment, and time to treatment failure. Interaction between an irinotecan-based regimen as a second-line treatment and double-dose bevacizumab after progression was associated with an improved overall survival (p = 0.06). Initiating systemic treatment with an irinotecan-based regimen in combination with bevacizumab improved the progression-free survival in the first-line treatment and time to treatment failure. In terms of overall survival, bevacizumab treatment after the first progression is better partnered with the same regimen as that used in the induction phase.

Interventional NIR Fluorescence Imaging of Cancer: Review on Next Generation of Dye-Loaded Protein-Based Nanoparticles for Real-Time Feedback During Cancer Surgery.

The use of fluorescence imaging technique for visualization, resection and treatment of cancerous tissue, attained plenty of interest once the promise of whole body and deep tissue near-infrared (NIR) imaging emerged. Why is NIR so desired? Contrast agents with optical properties in the NIR spectral range offer an upgrade for the diagnosis and treatment of cancer, by dint of the deep tissue penetration of light in the NIR region of the electromagnetic spectrum, also known as the optical window in biological tissue. Thus, the development of a new generation of NIR emitting and absorbing contrast agents able to overcome the shortcomings of the basic free dye administration is absolutely essential. Several examples of nanoparticles (NPs) have been successfully implemented as carriers for NIR dye molecules to the tumour site owing to their prolonged blood circulation time and enhanced accumulation within the tumour, as well as their increased fluorescence signal relative to free fluorophore emission and active targeting of cancerous cells. Due to their versatile structure, good biocompatibility and capability to efficiently load dyes and bioconjugate with diverse cancer-targeting ligands, the research area of developing protein-based NPs encapsulated or conjugated with NIR dyes is highly promising but still in its infancy. The current review aims to provide an up-to-date overview on the biocompatibility, specific targeting and versatility offered by protein-based NPs loaded with different classes of NIR dyes as next-generation fluorescent agents. Moreover, this study brings to light the newest and most relevant advances involving the state-of-the-art NIR fluorescent agents for the real-time interventional NIR fluorescence imaging of cancer in clinical trials.

Treatment beyond progression in metastatic colorectal cancer: to double or not to double the dose of bevacizumab?

PURPOSE: Bevacizumab or cetuximab represent the standard treatment in association with classical chemotherapy in confirmed metastatic colorectal cancer (mCRC). Bevacizumab could be continued after the first disease progression with an overall survival (OS) advantage, compared to chemotherapy alone, but the optimal dose remains a debatable issue. METHODS: In a retrospective analysis of mCRC patients treated with bevacizumab, we selected patients with administration beyond progression, and stratified them according to the dose received- same dose bevacizumab (SDB) as first-line chemotherapy or double dose bevacizumab (DDB). For each group we evaluated OS, time to treatment failure (TTF) and progression-free survival in the first-line (PFS1) and in the second-line (PFS2). RESULTS: In the first-line therapy, oxaliplatin backbone regimen was used in 73% SDB, compared with 22.5% DDB patients, while irinotecan was used in 75% DDB and 27% SDB patients. Second-line oxaliplatin was given to 50% DDB and 29.7% SDB patients, while irinotecan was administered to 47.5% DDB and 70.3% SDB patients. The median values were: OS - 41 months in the DDB group and 25 months in the SDB group (p = 0.01); TTF - 24 months in the DDB group and 19 months in the SDB group (p=0.009); PFS1 - 17 months in the DDB group and 12 months in the SDB group (p=0.008); PFS2 - 9 months in the DDB group and 5 months in the SDB group (p = 0.03). CONCLUSIONS: Doubling the dose of bevacizumab at progression seems to provide OS and PFS advantage for mCRC patients.

Design of fluorophore-loaded human serum albumin nanoparticles for specific targeting of NIH:OVCAR3 ovarian cancer cells.

Nowadays, extensive research is being carried out to find innovative solutions for the development of stable, reproductible, and highly efficient fluorescent contrast agents with the ability of targeting specific cells, which can be further implemented for fluorescent-guided surgery in a real clinical setting. The present study is focused on the development of fluorescent dye-loaded protein nanoparticles (NPs) to overcome the drawbacks of the standard administration of free organic fluorophores, such as cytotoxicity, aqueousinstability, and rapid photo-degradation. Precisely, human serum albumin (HSA) NPs loaded with two different FDA approved dyes, namely indocyanine green (ICG) and fluorescein isothiocyanate (FITC), with a fluorescence response in the near-infrared and visible spectral domains, respectively, have been successfully designed. Even though the diameter of fluorescent HSA NPs is around 30 nm as proven by dynamic light scattering and transmission electron microscopy investigations, they present good loading efficiencies of almost 50% for ICG, and over 30% for FITC and a high particle yield of over 75%. Molecular docking simulations of ICG and FITC within the structure of HSA confirmed that the dyes were loaded inside the NPs, and docked in Site I (subdomain IIA) of the HSA molecule. After the confirmation of their high fluorescence photostability, the NPs were covalently conjugated with folic acid (HSA-FA NPs) in order to bind specifically to the folate receptor alpha (FRα) protein overexpressed on NIH:OVCAR3 ovarian cancer cells. Finally, fluorescence microscopy imaging investigations validate the improved internalization of folate targeted HSA&FITC NPs compared to cells treated with untargeted ones. Furthermore, TEM examinations of the distribution of HSA NPs into the NIH:OVCAR3 cells revealed anincreased number of NP-containing vesicles for the cells treated with HSA-FA NPs, compared to the cells exposed to untargeted HAS NPs, upholding the enhanced cellular uptake through FRα-mediated potocytosis.

Multimodal Biosensing on Paper-Based Platform Fabricated by Plasmonic Calligraphy Using Gold Nanobypiramids Ink.

In this work, we design new plasmonic paper-based nanoplatforms with interesting capabilities in terms of sensitivity, efficiency, and reproducibility for promoting multimodal biodetection via Localized Surface Plasmon Resonance (LSPR), Surface Enhanced Raman Spectroscopy (SERS), and Metal Enhanced Fluorescence (MEF). To succeed, we exploit the unique optical properties of gold nanobipyramids (AuBPs) deposited onto the cellulose fibers via plasmonic calligraphy using a commercial pen. The first step of the biosensing protocol was to precisely graft the previously chemically-formed p-aminothiophenol@Biotin system, as active recognition element for target streptavidin detection, onto the plasmonic nanoplatform. The specific capture of the target protein was successfully demonstrated using three complementary sensing techniques. As a result, while the LSPR based sensing capabilities of the nanoplatform were proved by successive 13-18 nm red shifts of the longitudinal LSPR associated with the change of the surface RI after each step. By employing the ultrasensitive SERS technique, we were able to indirectly confirm the molecular identification of the biotin-streptavidin interaction due to the protein fingerprint bands assigned to amide I, amide III, and Trp vibrations. Additionally, the formed biotin-streptavidin complex acted as a spacer to ensure an optimal distance between the AuBP surface and the Alexa 680 fluorophore for achieving a 2-fold fluorescence emission enhancement of streptavidin@Alexa 680 on the biotinylated nanoplatform compared to the same complex on bare paper (near the plasmonic lines), implementing thus a novel MEF sensing nanoplatform. Finally, by integrating multiple LSPR, SERS, and MEF nanosensors with multiplex capability into a single flexible and portable plasmonic nanoplatform, we could overcome important limits in the field of portable point-of-care diagnostics.

SChitosan-capped gold nanoparticles impair radioresistant glioblastoma stem-like cells.

PURPOSE: Glioblastoma is a rapidly evolving lethal disease mainly due to its highly chemo- and radioresistant glioblastoma stem cells (GSCs). Herein, we tested if chitosan-capped gold nanoparticles (Chit-GNPs) may overcome the limitations of drug concentrations by increased cell internalization in GSCs and if such GNPs could enhance the response to irradiation. METHODS: Chitosan was used for Chit-GNP synthesis as a reducing and stabilizing agent. Chit-GNPs were characterized by spectroscopy, dark field, transmission electron microscopy and zeta potential measurements. Patient-derived GSCs and human osteoblasts were treated with increasing concentrations of nanoparticles and irradiated. The uptake and cytotoxicity of Chit-GNPs were compared to that of uncoated GNPs. RESULTS: The positively-charged, 26 nm-sized, spherical Chit-GNPs, showed a huge intracellular accumulation into the cytosol, lysosomes and near the nucleus, whereas no uncoated GNPs were internalized within GSCs. Surprisingly, Chit-GNPs were highly cytotoxic for GSCs irrespective of cell irradiation, that failed to add an additional benefit when combined with Chit-GNPs/GNPs. Moreover, Chit-GNPs were selectively cytotoxic for GSCs and did not affect the normal cells, despite an increased nanoparticle internalization. CONCLUSIONS: The important Chit-GNP internalization and their selective cytotoxicity for GSCs make this compound a potential novel anticancer agent and a promising backbone for drug delivery in glioblastoma.

Gold NanoBipyramids Performing as Highly Sensitive Dual-Modal Optical Immunosensors.

In this work, we demonstrate the feasibility of gold bipyramidal-shaped nanoparticles (AuBPs) to be used as active plasmonic nanoplatforms for the detection of the biotin-streptavidin interaction in aqueous solution via both Localized Surface Plasmon Resonance and Surface Enhanced Raman Scattering (LSPR/SERS). Our proof of concept exploits the precise attachment of the recognition element at the tips of AuBPs, where the electromagnetic field is stronger, which is beneficial to the surface sensitivity of longitudinal LSPR on the local refractive index and to the electromagnetic enhancement of SERS activity, too. Indeed, successive red shifts of the longitudinal LSPR associated with increased local refractive index reveal the attachment of para-aminothiophenol (p-ATP) chemically labeled Biotin to the Au surface and the specific capture of the target protein by biotin-functionalized AuBPs. Finite-Difference Time-Domain simulations based on the reconstructed index of refraction confirm LSPR measurements. However, the molecular identification of the biotin-streptavidin interaction remains elusive by LSPR investigation alone. Remarkably, we succeeded to complement the LSPR detection with reliable SERS measurements which permitted to (a) certify the molecular identification of biotin-streptavidin interaction and (b) extend the limit of detection of streptavidin in solution toward 10-12 M. Finally, to further probe the possibility to implement the AuBPs as dual LSPR-SERS based immunoassays in solution for real clinical diagnostics, we additionally investigated the AuBP's performance to transduce the specific antihuman IgG- human IgG binding event, providing thus a reference design for building unique plasmonic immunoassays for dual-optical detection of target proteins in aqueous solution.

Doxorubicin-Incorporated Nanotherapeutic Delivery System Based on Gelatin-Coated Gold Nanoparticles: Formulation, Drug Release, and Multimodal Imaging of Cellular Internalization.

In this work, we developed a new pH- and temperature-responsive nanochemotherapeutic system based on Doxorubicin (DOX) noncovalently bound to biosynthesized gelatin-coated gold nanoparticles (DOX-AuNPs@gelatin). The real-time release profile of DOX was evaluated at different pH values (7.4, 5.3, and 4.6) and temperatures (22-45 °C) in aqueous solutions, and its therapeutic performance was examined in vitro against MCF-7 breast cancer cells. TEM, dark-field scattering, and wide-field fluorescence microscopy indicated the effective uptake of nanochemotherapeutics with the subsequent release and progressive accumulation of DOX in cell nuclei. MTT assays clearly showed the effectiveness of the treatment by inhibiting the growth of MCF-7 breast cancer cells for a loaded drug concentration of 5 µg/mL. The most informative data about the dynamic release and localization were provided by scanning confocal microscopy using time-resolved fluorescence and surface-enhanced Raman scattering (SERS) techniques. In particular, fluorescence-lifetime imaging (FLIM) recorded under 485 nm pulsed diode laser excitation revealed the bimodal distribution of DOX in cells. The shorter fluorescence lifetime of DOX localized in nuclei (1.52 ns) than in the cytoplasm (2.4 ns) is consistent with the cytotoxic mechanism induced by DOX-DNA intercalation. Remarkably, the few DOX molecules captured between nanoparticles ("electromagnetic hotspots") after most drug is released act as SERS reporters for the localization of plasmonic nanocarriers in MCF-7 cells. The high drug loading capacity and effective drug release under pH control combined with the advantage of multimodal visualization inside cells clearly indicate the high potential of our DOX-AuNPs@gelatin delivery system for implementation in nanomedicine.

A simple and efficient design to improve the detection of biotin-streptavidin interaction with plasmonic nanobiosensors.

In this manuscript we propose a simple and efficient strategy to improve the sensitivity of localized surface plasmon resonance (LSPR) shift-based biosensors using biotin-streptavidin recognition interaction as a proof-of-concept. Specifically, biotin molecules are immobilized on a low-cost plasmonic LSPR biosensor based on annealed self-assembled spherical gold nanoparticles (AuNSs) and successively incubated with increasing concentrations of streptavidin, achieving a limit of detection (LOD) of 5nM. Interestingly, when the detection is performed by the same biotin-functionalized plasmonic AuNSs substrate but against streptavidin previously conjugated to gold nanorods, the LSPR shift is 26-fold enhanced. Moreover, we confirm these results through numerical simulations and demonstrate that the proposed sensing architecture can operate as transducer not only to confirm the adsorption of bioanalyte but also to provide the chemical identity of the capture and targeted molecules from their vibrational Raman fingerprints. Therefore, we are confident that the development of such plasmonic biosensors that use metallic labels for improving the sensitivity of detection could become highly promising for future point-of-care diagnostic assays, pushing sensitivity towards single-molecule detection limit.

One-pot, green synthesis of gold nanoparticles by gelatin and investigation of their biological effects on Osteoblast cells.

It is useful to find new methods to synthesize and, more importantly, to control the size and shape of gold nanoparticles (AuNPs) without using relatively toxic-reducing agents and surfactants. In this work, we present a one-pot, green synthesis of AuNPs taking the advantage of gelatin biopolymer to operate as unique reducing, growth controlling and stabilizing agent in aqueous solution of tetrachloroauric acid (HAuCl4) at temperatures above its melting point (∼35°C). The shape and size of AuNPs were found to be strongly influenced by the gelatin concentration (0.5-5%), while the growth rate of AuNPs is controlled by temperature of synthesis (40-80°C) and viscosity of the biopolymer. A specific class of gelatin-coated AuNPs was selected to investigate its stability in simulated physiological conditions and cellular media and subsequently to evaluate the in vitro biocompatibility and capacity to sustain proliferation and differentiation of Osteoblast cells. Dark-field microscopy and Rayleigh scattering spectra prove a more efficient internalization of gelatin-coated AuNPs as compared with citrate-coated AuNPs, while methylthiazoltetrazolium bromide (MTT) assay demonstrates enhanced cell proliferation. Interestingly, in the presence of gelatin-coated AuNPs, we find out a first sign of Osteoblast cells differentiation with bone nodules formation, as confirmed by alkaline phosphatase (ALP) activity assay.

Gelatin-nanogold bioconjugates as effective plasmonic platforms for SERS detection and tagging.

It is well known that standard citrate-reduced gold nanoparticles (AuNPs) are unstable at high ionic strength solution, which limits their applications in the biomedical field. In this work we present an environmentally friendly approach for the stabilization of citrate-reduced AuNPs in aqueous solution. Specifically, the stability of the AuNPs against salt-induced aggregation was greatly improved in the presence of gelatin biopolymer and stabilization of individual or small assemblies of nanoparticles can be controlled by the amount of gelatin. Furthermore, the gelatin-nanogold bioconjugates were demonstrated to be operational as highly sensitive surface-enhanced Raman scattering (SERS) active substrate for the detection of Rose Bengal fluorophore in solution at very low concentration. The results suggest that such bioconjugates can be successfully employed not only for detection of analytes, but more interestingly for building SERS-active tags in view of imaging purpose. The stabilization of bioconjugates was analyzed by localized surface plasmon resonance spectroscopy (LSPR), transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta-potential, and the chemical interaction of gelatin with AuNPs was inferred from Fourier transform infrared spectroscopy (FT-IR).