## 1 Introduction
### Nanotechnology Offers Diagnostic and Antibacterial and Antibiofilm Properties  
There is a robust demand to research novel antibacterial agents that defeat the global antibiotic resistance crisis to avert returning to the pre-penicillin era [46] or entering the post-antibiotic era, where common bacterial infections could kill [99; 100]. This demand includes novel multi-targeted antibacterial agents effective against multi-(bacterial species and faceted properties) of biofilms [53; 59; 70; 80]. Nanoparticles (NPs) could combat superbugs due to their unique physicochemical properties, generating heightened therapeutic effects against planktonic cells and biofilms [74; 101]. The fundamental three antibacterial mechanisms of NPs are central to (i) induction of oxidative stress through the production of reactive oxygen species (ROS) that disrupt bacterial membranes, inactivate essential proteins and enzymes, and express oxidative proteins. (ii) Release of metal ions, interacting with functional groups (e.g., phosphates, sulfhydryl, carboxyl, amino) of DNA and proteins and disrupting their physiological functions. (iii) Induction of non-oxidative stress through the interaction of NPs with bacterial cell membranes, resulting in cytoplasmic leakage [47; 74]. The main antibacterial prowess of NPs is that these antibacterial mechanisms could coincide, decreasing the probability of bacteria to develop resistance because multiple simultaneous bacterial gene mutations would be required [47; 101; 102]. Therefore, antibacterial NPs could achieve the outstanding concept of'resistance-resistant', where multi-target bacterial inhibition occurs, and NPs become more resistant to resistance development. This concept would be a technological leapfrog rather than discovering novel antibiotics, which could be a daunting process and an economic burden [103]. Considering the pioneering properties of antibacterial NPs, how could these properties have a pivotal role in inhibiting or eradicating the biofilm dilemma? To date, the fundamental answer is the size of NPs (5 to 200 nm) that allow their penetration through the fluid channels (10 nm to few micrometers) of biofilms [74]. Even though more than a hundred years have elapsed since [PERSON] was awarded the Nobel Prize, his concept of developing \"_magic bullets_\" still dominates a significant area of interest within the field of pharmaceuticals [104; 105]. This domination stems from the promising therapeutic efficacies and the minimal drawbacks of these magic bullets because they specifically target certain bacteria, killing them with a few harmful side effects on other body tissues [105]. By contrast, biofilm infections are similar to a fortress of multispecies bacterial communities and multifaceted physical and biological properties, providing shelter against single \"magic bullet\" strategies [70]. In terms of targeted drug delivery, NPs could also be used as potential drug carriers, facilitating targeted delivery and the controlled release of drugs [47; 102]. If NPs could combat the bacterial resistance and biofilm dilemma, then how would nanotheranostics potentially revolutionize medicine? It is necessary here to first clarify what is meant by theranostics. The term \"theranostics\" is commonly referred to as a combination of diagnostic and therapeutic properties into a single component [106; 107] and emerging as a powerful platform toward personalized medicine [106; 108]. Speaking on the aimed personalized medicine, it extends beyond the warm, caring manner to patients [109] and the traditional idea of one drug fitting all patients toward administering the specific drug to the right patient at the right time [108]. The availability of a single agent for diagnosis and treatment is at the heart of challenges facing the transfer ofranostics into the clinical field; however, nanotechnology can cross this challenge by entangling diagnostics and therapeutic agents [108].