No abstract

The utilization of toxic chemicals as reducing and stabilizing agents in the preparation of gold nanoparticles (AuNPs) has increased in vivo toxicity and thus limited its application in clinical settings. Herein, we propose an alternative method of preparing highly stable AuNPs, where non-toxic Curcuma mangga (CM) extract was used as a single reducing and stabilizing agent to overcome the aforementioned constraints. The morphological images enunciated that the homogeneously dispersed AuNPs exhibited spherical morphology with an average particle diameter of 15.6 nm. Fourier Transform infrared (FTIR) and cyclic voltammetry analysis demonstrated that carbonyl groups of terpenoids in CM extract played an important role in the formation and stabilization of AuNPs. Green-synthesized AuNPs were found to have good stability in physiological media after 24 h of dispersion. The AuNPs were also cytocompatible with human colon fibroblast cell (CCD-18Co) and human lung fibroblast cell (MRC-5). Hemocompatibility tests revealed that the AuNPs were blood-compatible, with less than 10% of hemolysis without any aggregation of erythrocytes. The current study suggests potential in employing a CM-extract-based method in the preparation of AuNPs for anticancer diagnosis and therapy.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters the cells through the binding of its spike protein (S-protein) to the cell surface-expressing angiotensin-converting enzyme 2 (ACE2). Thus, inhibition of S-protein-ACE2 binding may impede SARS-CoV-2 cell entry and attenuate the progression of Coronavirus disease 2019 (COVID-19). In this study, an electrochemical impedance spectroscopy-based biosensing platform consisting of a recombinant ACE2-coated palladium nano-thin-film electrode as the core sensing element was fabricated for the screening of potential inhibitors against S-protein-ACE2 binding. The platform could detect interference of small analytes against S-protein-ACE2 binding at low analyte concentration and small volume (0.1 μg/mL and ~1 μL, estimated total analyte consumption < 4 pg) within 21 min. Thus, a few potential inhibitors of S-protein-ACE2 binding were identified. This includes (2S,3aS,6aS)-1-((S)–N-((S)-1-Carboxy-3-phenylpropyl)alanyl)tetrahydrocyclopenta[b] pyrrole-2-carboxylic acid (ramiprilat) and (2S,3aS,7aS)-1-[(2S)-2-[[(2S)-1-Carboxybutyl]amino]propanoyl]-2,3,3a,4,5,6,7,7a-octahydroindole-2-carboxylic acid (perindoprilat) that reduced the binding affinity of S-protein to ACE2 by 72% and 67%; and SARS-CoV-2 in vitro infectivity to the ACE2-expressing human oral cavity squamous carcinoma cells (OEC-M1) by 36.4 and 20.1%, respectively, compared to the PBS control. These findings demonstrated the usefulness of the developed biosensing platform for the rapid screening of modulators for S-protein-ACE2 binding.

Nanosized constructs are widely applied to address the common drawbacks of conventional cancer therapy, such as a nonspecific biodistribution, toxicity and targeting. Nevertheless, there are several challenges in transporting sufficient drugs to the tumor using these nanoconstructs, which are discussed in this review. Additionally, the current opportunities that improve the biodistribution of nanoconstructs, tumor penetration and drug accumulation are elaborated. The distinct features of currently available strategies do not adequately fit the classical passive and active targeting categories; therefore, in this review, they are regrouped into autonomous and nonautonomous drug delivery systems. Autonomous systems are defined as self-directed systems that can enhance nanoparticle retention and distribution in solid tumors without the need to align with the blood flow direction, while non-autonomous systems primarily rely on the blood flow direction, longevity in the circulation and specific affinity to the target cells. Moreover, the effectiveness of the existing delivery systems could be further improved through the correct choice of route of administration. The role of the route of administration in improving these drug delivery methods and some recent examples of locoregional cancer therapy are discussed. These findings could stimulate improvements in the delivery of multifunctional nanoconstructs, which could facilitate successful cancer treatments.

Porous silicon electroluminescent devices have been fabricated from n-type substrates using indium tin oxide, hole-transporting poly(9-vinyl carbazole) and p-type nickel oxide films as hole injecting contacts. The addition of the polymer layer, which increases the contact area by penetrating into the porous microstructure, leads to an increase in the device quantum efficiency of two orders of magnitude. The replacement of indium tin oxide by nickel oxide, formed by a thermal evaporation process, lowers the device switch-on voltage from 55-60 V to 10-15 V. The p-type nature of the nickel oxide film allows holes to be injected from the valence band of the contact, and hence at a lower applied voltage than that required for indium tin oxide contacts. The luminescence power output from both devices is similar, and we suggest that the limiting factor in the luminescent output is the rate of carrier flow throughout the device nanostructures.