Delineating the Role of Tailored Gold Nanostructures at the Biointerface

Synthesis and toxicity assessment of Coffea arabica extract-derived gold nanoparticles loaded with doxorubicin in lung cancer cell cultures

Cancer is the second leading cause of death worldwide, despite the many treatments available, cancer patients face side effects that reduce their quality of life. Therefore, there is a need to develop novel strategies to increase the efficacy of treatments. In this study, gold nanoparticles obtained by green synthesis with Coffea arabica green bean extract were loaded with Doxorubicin, (a highly effective but non-specific drug) by direct interaction and using commercial organic ligands that allow colloidal dispersion at physiological and tumor pH. Conjugation of these components resulted in stable nanohybrids at physiological pH and a tumor pH release dependent, with a particle size less than 40 nm despite having the ligands and Doxorubicin loaded on their surface, which gave them greater specificity and cytotoxicity in H69 tumor cells.

Metal-based nanoparticles: an alternative treatment for biofilm infection in hard-to-heal wounds

Metal-based nanoparticles (MNPs) are promoted as effective compounds in the treatment of bacterial infections and as possible alternatives to antibiotics. These MNPs are known to affect a broad spectrum of microorganisms using a multitude of strategies, including the induction of reactive oxygen species and interaction with the inner structures of the bacterial cells. The aim of this review was to summarise the latest studies about the effect of metal-based nanoparticles on pathogenic bacterial biofilm formed in wounds, using the examples of Gram-positive bacterium Staphylococcus aureus and Gram-negative bacterium Pseudomonas aeruginosa, as well as provide an overview of possible clinical applications.

Detection of antibodies against SARS-CoV-2 Spike protein by screen-printed carbon electrodes modified by colloidal gold nanoparticles

In this work, electrochemical bioanalytical systems for the determination of antibodies against the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Spike protein (anti-rS) is reported. Environmentally friendly chemicals were applied in the synthesis of gold nanoparticles (AuNPs). The AuNPs were integrated onto the screen-printed carbon electrodes (SPE), and the biological recognition part was based on recombinant SARS-CoV-2 Spike protein (rS), which during the immobilization was cross-linked by glutaraldehyde. Immobilized rS protein based biological recognition part enabled selective recognition of anti-rS antibodies. The current flux of AuNPs reduction (at +200 mV) in a pure phosphate buffer (PB) was employed as the transduction signal. It has been reported that the formation of anti-rS layers on the surface of AuNPs delays the electrode response time (ts), tracked at the current flux density values of 80 μA cm-2. Using the AuNP-modified SPE, we demonstrated a rapid anti-rS detection within a detection limit of 2 ng mL-1 (0.125 binding antibody units mL-1, 17 pM). This system can be applied to track the response of immune system towards SARS-CoV-2 infection and monitoring of Coronavirus Disease 2019 (COVID-19).

CO2-Responsive Rosin-Based Supramolecular Hydrogels: Diverse Chiral Nanostructures and Their Application in In Situ Synthesis of Chiral Gold Nanoparticles

Natural small molecules have demonstrated tremendous potential for the construction of supramolecular chiral nanostructures owing to their unique molecular structures and chirality. In this study, novel CO2-responsive supramolecular hydrogels were constructed using a series of rosin-based surfactants (CnMPAN, n = 10, 12, and 14). The macroscopic properties, rheological properties, nanostructures, and intermolecular interactions of the hydrogels were investigated using differential scanning calorimetry, rotational rheometry, cryogenic transmission electron microscopy, and Fourier transform infrared spectroscopy. Interestingly, diverse nanostructures containing helical nanofibers, interwoven nanofibers, and twisted nanoribbons were formed in the hydrogels, which were rarely observed in reported supramolecular hydrogels, and the strength of the hydrogels was significantly enhanced by increasing the CnMPAN concentration and the alkyl chain length. The obtained hydrogels exhibited excellent CO2-responsiveness, with no obvious variation in the nanostructures and rheological properties after response to CO2/N2 for five cycles. Taking advantage of the chiral nanostructures of hydrogels, gold nanoparticles (GNPs) were further prepared. The average particle sizes of the resulting GNPs were as low as 2.5 nm, and the GNPs also had a chiral structure. It is worth noting that no additional reductants and UV-light irradiation were used during the reduction process of GNPs. This study emphasizes that the unique molecular structure and chirality of rosin are critical for the preparation of hydrogels with chiral nanostructures. In addition, this study enriches the applications of forest resources.

Curcumin-capped gold nanorods as optical sensing platform for sequence specific detection of DNA based on their self-assembly

We are reporting curcumin-induced gold nanorods as an optical sensing platform for the detection of sequence-specific DNA target through their self-assembly. The combined effect of eco-friendly reducing agent (i.e., curcumin) and silver nitrate in a basic medium (i.e., pH 10) has been attributed for the formation of small gold nanorods (AuNRs) having approximate length and diameter i.e., 19.7 ± 0.8 nm and 6.0 ± 0.5 nm, respectively, and lower longitudinal surface plasmon resonance (SPR) enable to detect and analyse different biomarkers. Further, for evaluating cellular uptake of as-synthesized AuNRs, the cytotoxicity study has been carried out by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay on A549 cells and HEPG2 cell lines, respectively, and shown approximately similar cytotoxicity. Interestingly, as-synthesized optically and electronically active AuNRs based nanobiosensing platform enable to detect sequence-specific DNA targets with low level of detection limit i.e., LOD 8.6 ± 0.15 pM for complimentary target (CT) DNA with higher sensitivity and better selectivity. Finally, this study is suggesting a simplistic bio-mediated approach of tuning the shape and size of AuNRs for sensitive, selective and reliable nanobiosensing platform for sequence-specific DNA detection related to cancer cells.

Polymer Chemistry Defines Adjuvant Properties and Determines the Immune Response against the Antigen or Vaccine

Activation of the immune system is a needed for designing new antigen/drug delivery systems to develop new therapeutics and for developing animal disease models to study the disease pathogenesis. A weak antigen alone is insufficient to activate the immune system. Sometimes, assistance in the form of polymers is needed to control the release of antigens under in vivo conditions or in the form of an adjuvant to activate the immune system efficiently. Many kinds of polymers from different functional groups are suitable as microbial antigens for inducing therapeutic immune responses against infectious diseases at the preclinical level. The choice of the functionality of polymer varies as per the application type. Polymers from the acid and ester groups are the most common types investigated for protein-based antigens. However, electrostatic interaction-displaying polymers like cationic polymers are the most common type for nucleic acid-based antigens. Metal coordination chemistry is commonly used in polymers designed for cancer immunotherapeutic applications to suppress inflammation and induce a protective immune response. Amide chemistry is widely deployed in polymers used to develop antigen-specific disease models like the experimental autoimmune arthritis murine model.

Synthesis and Characterization of Gold Chiral Nanoparticles Functionalized by a Chiral Drug

Inorganic chiral nanoparticles are attracting more and more attention due to their peculiar optical properties and potential biological applications, such as bioimaging, therapeutics, and diagnostics. Among inorganic chiral nanoparticles, gold chiral nanostructures were demonstrated to be very interesting in this context, with good physical chemical stability and also the possibility to decorate the surface, improving biomedical application as the interaction with the bio-systems. Gold (Au) nanostructures were synthesized according to a seed-mediated procedure which envisages the use of cetyltrimethylammonium bromide (CTAB) as the capping agent and L- and D-cysteine to promote chirality. Au nanostructures have been demonstrated to have opposite circular dichroism signals depending on the amino acid enantiomer used during the synthesis. Then, a procedure to decorate the Au surface with penicillamine, a drug used for the treatment of Wilson's disease, was developed. The composite material of gold nanoparticles/penicillamine was characterized using electron microscopy, and the penicillamine functionalization was monitored by means of UV-Visible, Raman, and infrared spectroscopy, highlighting the formation of the Au-S bond. Furthermore, electron circular dichroism was used to monitor the chirality of the synthesized nanostructures and it was demonstrated that both penicillamine enantiomers can be successfully bonded with both the enantiomers of the gold nanostructures without affecting gold nanoparticles' chirality. The effective modification of nanostructures' surfaces via penicillamine introduction allowed us to address the important issue of controlling chirality and surface properties in the chiral nano-system.

Fluro-Protein C-Phycocyanin Docked Silver Nanocomposite Accelerates Cell Migration through NFĸB Signaling Pathway

Currently, there is a great demand for the development of nanomedicine aided wound tissue regeneration via silver doped nanoceuticals. Unfortunately, very little research is being carried out on antioxidants-doped silver nanometals and their interaction on the signaling axis during the bio-interface mechanism. In this study, c-phycocyanin primed silver nano hybrids (AgcPCNP) were prepared and analyzed for properties such as cytotoxicity, metal decay, nanoconjugate stability, size expansion, and antioxidant features. Fluctuations in the expression of marker genes during cell migration phenomena in in vitro wound healing scenarios were also validated. Studies revealed that physiologically relevant ionic solutions did not exhibit any adverse effects on the nanoconjugate stability. However, acidic, alkali, and ethanol solutions completely denatured the AgcPCNP conjugates. Signal transduction RT²PCR array demonstrated that genes associated with NFĸB- and PI3K-pathways were significantly (p < 0.5%) altered between AgcPCNP and AgNP groups. Specific inhibitors of NFĸB (Nfi) and PI3K (LY294002) pathways confirmed the involvement of NFĸB signaling axes. In vitro wound healing assay demonstrated that NFĸB pathway plays a prime role in the fibroblast cell migration. In conclusion, the present investigation revealed that surface functionalized AgcPCNP accelerated the fibroblast cell migration and can be further explored for wound healing biomedical applications.

Metal Nanoparticles to Combat Candida albicans Infections: An Update

Candidiasis is an opportunistic mycosis with high annual incidence worldwide. In these infections, Candida albicans is the chief pathogen owing to its multiple virulence factors. C. albicans infections are usually treated with azoles, polyenes and echinocandins. However, these antifungals may have limitations regarding toxicity, relapse of infections, high cost, and emergence of antifungal resistance. Thus, the development of nanocarrier systems, such as metal nanoparticles, has been widely investigated. Metal nanoparticles are particulate dispersions or solid particles 10-100 nm in size, with unique physical and chemical properties that make them useful in biomedical applications. In this review, we focus on the activity of silver, gold, and iron nanoparticles against C. albicans. We discuss the use of metal nanoparticles as delivery vehicles for antifungal drugs or natural compounds to increase their biocompatibility and effectiveness. Promisingly, most of these nanoparticles exhibit potential antifungal activity through multi-target mechanisms in C. albicans cells and biofilms, which can minimize the emergence of antifungal resistance. The cytotoxicity of metal nanoparticles is a concern, and adjustments in synthesis approaches or coating techniques have been addressed to overcome these limitations, with great emphasis on green synthesis.

Significance of Capping Agents of Colloidal Nanoparticles from the Perspective of Drug and Gene Delivery, Bioimaging, and Biosensing: An Insight

The over-growth and coagulation of nanoparticles is prevented using capping agents by the production of stearic effect that plays a pivotal role in stabilizing the interface. This strategy of coating the nanoparticles’ surface with capping agents is an emerging trend in assembling multipurpose nanoparticles that is beneficial for improving their physicochemical and biological behavior. The enhancement of reactivity and negligible toxicity is the outcome. In this review article, an attempt has been made to introduce the significance of different capping agents in the preparation of nanoparticles. Most importantly, we have highlighted the recent progress, existing roadblocks, and upcoming opportunities of using surface modified nanoparticles in nanomedicine from the drug and gene delivery, bioimaging, and biosensing perspectives.

Amphotericin B-PEG Conjugates of ZnO Nanoparticles: Enhancement Antifungal Activity with Minimal Toxicity

Amphotericin B (AMB) is commonly used to treat life-threatening systemic fungal infections. AMB formulations that are more efficient and less nephrotoxic are currently unmet needs. In the current study, new ZnO-PEGylated AMB (ZnO-AMB-PEG) nanoparticles (NPs) were synthesized and their antifungal effects on the Candida spp. were investigated. The size and zeta potential values of AMB-PEG and ZnO-AMB-PEG NPs were 216.2 ± 26.9 to 662.3 ± 24.7 nm and −11.8 ± 2.02 to −14.2 ± 0.94 mV, respectively. The FTIR, XRD, and EDX spectra indicated that the PEG-enclosed AMB was capped by ZnO, and SEM images revealed the ZnO distribution on the surface NPs. In comparison to ZnO-AMB NPs and free AMB against C.albicans and C.neoformans, ZnO-AMB-PEG NPs significantly reduced the MIC and MFC. After a week of single and multiple dosage, the toxicity was investigated utilizing in vitro blood hemolysis, in vivo nephrotoxicity, and hepatic functions. ZnO-AMB-PEG significantly lowered WBC count and hematocrit concentrations when compared to AMB and ZnO-AMB. RBC count and hemoglobulin content, on the other hand, were unaltered. ZnO-AMB-PEG considerably lowered creatinine and blood urea nitrogen (BUN) levels when compared to AMB and ZnO-AMB. The difference in liver function indicators was determined to be minor by all formulae. These findings imply that ZnO-AMB-PEG could be utilized in the clinic with little nephrotoxicity, although more research is needed to determine the formulation’s in vivo efficacy.