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Marmatite and bornite are commonly associated together in nature, and their interactions in an acidic environment are vital for both (bio)hydrometallurgy and acid mine drainage (AMD) production. In this work, dissolution experiments (marmatite : bornite = 2 : 0, 3 : 1, 1 : 1, 1 : 3 and 0 : 2) accompanied by analytic techniques such as electrochemical methods, Raman spectroscopy and synchrotron radiation-XRD (SR-XRD) were utilized to interpret the interactions between marmatite and bornite in acidic abiotic and biotic systems. The dissolution experiments showed that marmatite can significantly accelerate the oxidative dissolution of bornite, especially in the abiotic system. On the contrary, bornite inhibited the oxidative dissolution of marmatite when the percentage of bornite was high. Electrochemical measurements proved that the galvanic interactions between marmatite and bornite were slight and should not be the main cause for the interactions. Combined with the dissolution experiments, analytic techniques and previous references, it could be speculated that marmatite accelerated bornite dissolution mainly by providing an iron source, which acted as the energy source for microorganisms and oxidants. Bornite affected the dissolution of marmatite mainly by Cu2+ ions dissolving from bornite. Bornite inhibited the oxidative dissolution of marmatite mainly because a high Cu2+ concentration could significantly hinder marmatite dissolution. In addition, the formation of elemental sulfur or jarosite was also one important cause. Bornite intensified marmatite dissolution when the percentage of bornite or the Cu2+ concentration was extremely low and then, a synergic dissolution process occurred.

Violacein is a bacterial quorum-sensing chromophore, also referred to as ‘purple treasure’ for its versatile utility in the pharmaceutical, food, cosmetic and textile industries. Moreover, it provides broad spectrum biological activity that is the subject of expansive scientific research. The major limitation in the drug delivery of violacein is its hydrophobic nature that results in poor bioavailability. Nanoparticles (NPs) coupled with these drugs tend to enhance their delivery, efficacy and safety profiles. In this study, we established that violacein capped silver NPs (vAgNPs) have shown enhanced stability with 3 to 10 times higher therapeutic effect against multidrug resistant bacteria, fungi and algae compared to starch capped silver NPs (cAgNPs). The surface plasmon resonance, size, shape, crystalline nature and capping agent of these NPs were studied with UV-Vis spectroscopy, Scanning Transmission Electron Microscopy, Atomic Force Microscopy, X-ray Diffraction and Fourier Transform Infrared Spectroscopy, respectively. This comparative study examines the efficacy of vAgNPs against cAgNPs and establishes that surface capping of AgNPs with violacein yields conjugative benefits, i.e., strengthening each other's therapeutic effect, increased bioavailability of violacein, higher stability and maneuvering the therapeutic effect of vAgNPs towards Gram positive bacteria.