1. Please check and comment entries here.
Table of Contents

    Topic review

    Functionalized Chitosan Nanomaterials

    Subjects: Polymer Science
    View times: 12
    Submitted by: Tanmay Sarkar

    Definition

    Quorum sensing (QS) is the mechanism by which the microbial colonies in a biofilm modulate and intercept communication without direct interaction. Hence, the eradication of biofilms through hindering this communication will lead to the successful management of drug resistance and may be a novel target for antimicrobial chemotherapy. Chitosan shows microbicidal activities by acting electrostatically with its positively charged amino groups, which interact with anionic moieties on microbial species, causing enhanced membrane permeability and eventual cell death. Therefore, nanoparticles (NPs) prepared with chitosan possess a positive surface charge and mucoadhesive properties that can adhere to microbial mucus membranes and release their drug load in a constant release manner. As the success in therapeutics depends on the targeted delivery of drugs, chitosan nanomaterial, which displays low toxicity, can be safely used for eradicating a biofilm through attenuating the quorum sensing (QS).

    1. Introduction

    The last decade has seen a marked increase in the development of multi-drug-resistant pathogenic organisms that have brought about significant threats for the health sector. Numerous alternative approaches are being taken to check the pathogenesis of these antibiotic-resistant microbes and strategies are being adopted to minimize their virulence [1][2]. The chronic-infection-causing recalcitrant microbes usually reside in the protective shield of their biofilm, which is actually a syntrophic association of microbes. Hence, exploration of the natural ways for biofilm eradication and innovations for biotechnological approaches to enhance their antibiofilm activity becomes a new and booming stream of research.
    Both microbes alone and the biofilm formed by them attach themselves to specific surfaces. The biofilm-associated cells are especially capable of forming an extracellular polymeric substance matrix (EPS), which can maintain decreased growth rates and allow for up- and down regulation of some specific genes [3][4]. The EPS matrix possesses a definite construction pattern and creates an optimal condition that allows the microbes to exchange genetic contents between the cells [5]. Moreover, the biofilm-forming cells undergo cell-to-cell communication via the process of quorum sensing (QS), by which they control the expression of genetic components in response to continuous changes in the density of the cell population [6]. QS is accomplished by various types of extracellular communication materials called autoinducers (AIs) [7], which are the chemical signaling molecules that are synthesized and released by these cells [8].
    Since QS plays a key role in bacterial infection and bacterial survival, eradication of the biofilm through the denaturation of the AI molecules will ensure the prevention of biofilm-associated infection. Several novel antibiofilm agents were developed for interfering with the QS cascade and thereby inhibiting the formation of biofilms [9][10].
    However, such interruption in cellular communication can be done via the mechanism of quorum quenching (QQ), which involves the process of disrupting the QS cascade [7]. The molecular mechanism of QQ includes the cleavage of QS signals, competitive inhibition, and acting against the major targets of QS, thereby bringing about hindrance in the maturation of biofilm.
    Present-day nanomaterials are largely used as alternate therapeutics due to their large surface-area-to-volume ratio and extensive reactivity, resulting in the development of the new field of “nanomedicines” [11][12][13]. The enhancement in the development of antimicrobial resistance has resulted in researchers thinking about ways to provide alternate therapeutics [14]. A fascinating thing about nanomaterials is that their efficacies are largely dependent on the shape and size of the nanostructural contents of the nanomaterials and these properties can usually be distinguished well from the bulk traditional material, which possesses the appearance of a continuous material [15]. This is why these nanomaterials create huge interest regarding their applications in different types of research and development fields related to biotechnology, biology, chemistry, biophysics, and many others [16].

    2. Quorum Sensing in Biofilm-Associated Microbes

    QS, being the key event behind biofilm formation, is the main target for blocking to achieve an antibiofilm effect. Apart from biofilm formation, QS regulates multiple processes that involve sporulation, bioluminescence, the production of various types of virulence factors, antibiotic biosynthesis, and the formation of biofilms [17][18]. The mechanism of QS in Gram-negative bacteria (Table 1) takes place via LuxI/LuxR type systems, which play an important role in the production of AIs, the signalling molecules [19].
    Table 1. Quorum-sensing (QS) systems of selected Gram-negative bacteria.

    SL No.

    Bacterial Organism Name

    Quorum-Sensing Molecules

    Genes

    Receptors

    References

    1.

    Chromobacterium violaceum

    C12-HSL

    N.A.

    N.A.

    [20]

    N.A.

    N.A.

    SdiA

    [21]

    AI-2

    LuxS

    LsrB

    [16][22]

    2.

    Pseudomonas aeruginosa

    C4-HSL

    RhlI

    RhlR

    [23]

    3-oxo-C12-HSL

    LasI

    LasR

    [24][25]

    3-oxo-C12-HSL

    NA

    QscR

    [3][26]

    PQS, HHQ

    PqsABCD, PqsH

    PqsR

    [27]

    3.

    Staphylococcus aureus

    3-hydroxy-C4-HSL

    LuxM

    LuxN

    [3][26]

    AI-2

    LuxS

    LuxP

    [28]

    CAI-1

    CqsA

    CqsS

    [29]

    4.

    Acinetobacter baumannii

    3-hydroxy-C12-HSL

    AbaI

    AbaR

    [30]

    5.

    Escherichia coli

    3-oxo-C8-HSL

    N.A.

    SdiA

    [31][21]

    AI-2

    LuxS

    LsrB

    [23][32][33]

    AI-3/Epinephrine/Norepinephrine

    N.A.

    QseC

    [34]

    6.

    Klebsiella pneumoniae

    C8-HSL

    N.A.

    N.A.

    [15][22]

    C12-HSL

    N.A.

    N.A.

    [31]

    AI-2

    LuxS

    LsrB

    [35][36]

    3. Chitosan Nanoparticles

    A biofilm matrix acting as a scaffold provides a protective covering for sessile bacteria, making them drug resistant [37]. Hence, a more effective drug delivery system needs to be applied that can target both the biofilm matrix and the embedded sessile bacterial cells. Chitosan and its derivatives, with their acclaimed biofilm inhibiting property, may be used but in a more precise manner to halt the quorum sensing.
    Nanoparticles, with atomic dimensions of 10Å to 100Å [38] were shown to be quite effective for drug delivery. Despite a few drawbacks, including poor absorption and dissolution rate with reduced bioavailability, using nanoparticles is a much safer method, as these microscopic particles act as nanocarriers, encasing high drug payloads and provide more targeted action with a controlled release.
    Chitin, a natural polymer of β-(1,4)-N-acetyl-D-glucosamine, turns into chitosan, a polysaccharide composed of N-acetylglucosamine and D-glucosamine units [39], upon deacetylation in the presence of an alkali. Due to its cationic nature, biodegradability, compatibility, and nontoxicity, chitosan is used extensively by nano-biomedical researchers [40][41][42] for the delivery and controlled release of biomolecules, such as proteins, peptides, enzymes, genes, vaccines, and small drug molecules [43] via various delivery routes, including oral, buccal, vaginal, and pulmonary. Chitosan NPs are also used as vaccine adjuvants due to the mucoadhesive properties of chit, which can stimulate the cells of the immune system [44]. Some of the important properties of chitosan that have led to its wide range of applications in various fields (such as NPs) include mucoadhesion (as shown by trimethyl chitosan and carboxymethyl chitosan) [45]; controlled drug release, which enhances its effectiveness for drug delivery [46]; permeation enhancement, as shown by trimethyl chitosan [47]; antibacterial activity; no cytotoxicity; biocompatibility; and biodegradability. These properties are incredibly advantageous for the advancement of biocompatible and biodegradable medication conveyance frameworks [48][49].
    Since its first emergence in the mid-1990s, the chitosan nanoparticle (ChNP) has been used for drug delivery [50]. The property that is responsible for the success of ChNPs in drug delivery is its ability to bind with negatively charged anions to form beads. However, beads larger than approximately 2mm generally hinder this process [51]. The discovery of the ChNPs involves various ‘bottom-up’ or ‘top-down’ approaches, or a synergistic combination of both techniques. However, among the regular ‘bottom-up’ methods, the most popular ones are ionotropic gelation and the polyelectrolyte complex method [52] due to their straightforwardness and non-requirement of high shear power and natural solvents [53], unlike the ‘top-down’ methods of milling, ultrasonication, and high-pressure homogenization [49][54].Irrespective of the methodology adopted for their preparation, the ChNPs are regularly used for drug delivery to combat several diseases with appreciable efficacy. Although the precise mode of antimicrobial action is not determined completely, it was proposed that the molecular structure of chitosan is imperative for its antimicrobial activities. The antibacterial potential of chitosan is strongly influenced by several factors, such as its type, degree of polymerization, and physicochemical properties.

    4. Inhibition of Biofilm Formation Using Functionalized Chitosan Nanoparticles

    However, in order to target biofilm-associated chronic infections, medical devices, and food industries [55], the ChNPs must have the ability to block quorum sensing. It was revealed from various experimental observations that the positively charged ChNPs are usually loaded in Oxa or oxacillin and ChNP–DNase–Oxa or Deoxyribonuclease I [56]. The anti-biofilm activity is generally studied against the biofilm network formed by nosocomial bacterial species, such as Staphylococcus aureus and Pseudomonas aeruginosa. Biofilm structuring on silicone surfaces was checked and researched with the help of SEM or scanning electron microscopy [57]. Confocal laser scanning microscopy (CLSM) was used for looking upon alive or dead microorganisms inside the biofilm matrix, which revealed that ChNP–DNase–Oxa had a higher level of anti-biofilm activity than the Oxa-mixed nanoparticles, which is present without the ChNP–Oxa or the DNase and the summation of Oxa and DNase, which involves free Oxa [27][58]. Both the formation of new biofilms and the eradication of mature biofilms in vitro could be achieved with the help of the ChNP–DNase–Oxa. Actually, through the denaturation of eDNA, ChNP–DNase–Oxa can damage the biofilm matrix, decrease the width of the biofilm, and the number of viable cells on silicone. Back-to-back treating with the help of ChNP–DNase–Oxa over two days was seen to give a shocking and successful result of almost a 99% decrease in the biofilm [59]. Moreover, ChNP–DNase–Oxa was found to be effective against the biofilm of any type of normal and clinical strains of Staphylococcus aureus [58].
    This shows the high potential and effectivity of nanoparticles for treating the infections associated with biofilms [60]. Attenuation of the signals of bacterial quorum sensing can inhibit infection and can also stop the generation of bacterial virulence. Many research works have been conducted and almost all of them showed that the natural compounds possess more effectiveness over artificially synthesized chemicals regarding their treatment of biofilms and establishing them as anti-quorum-sensing agents.
    Especially, flavonoid compounds are highly efficient anti-microbial and antibiofilm compounds. However, due to the very low or no dissolution of the flavonoid molecules and the rare bioavailability, minimal application of flavonoids is found [61]. Experimental observations revealed that phytochemicals, when mixed with chitosan nanoparticles, significantly decreased the QS activity through the inactivation of AI molecules [62]. Kaempferol, a flavonoid, is known to possess high-anti-quorum-sensing activity [63]. The application of the kaempferol and chitosan nanoparticles was analyzed on the basis of their properties of hydrogen bonding, hydrodynamic diameter, antioxidant activity, and amorphous transformation. After this, the inhibition of the quorum-sensing molecules by the nanoparticles in a time-dependent pattern is usually studied [64]. This measurement is done in a violacein pigment with the help of a biosensor strain Chromobacterium violaceum CV026, which is again operated by an AI known as acylated homoserine lactone (AHL) [65]. Kaempferol-loaded sodium tripolyphosphate (TPP)on ChNPshave typical particle sizes and zeta potentials of 190 to 200 nm and +30 to +35 mV, respectively, and can be stored up to 30 days and still successfully inhibit the quorum-sensing molecules, namely, the violacein pigment, in Chromobacterium violaceum CV026 [66]. After the success of this method, attempts are being made to use it as a novel antimicrobial chemotherapy. In this process, the kaempferol-encapsulated chitosan nanoparticles play the role of a stable and effective quorum-sensing-dependent antimicrobial, antibacterial, and antibiofilm agent [67].
    Quercetin (QUE), another flavonoid phytocompound that is found in many commonly used medicinal plants [68] holds strong potential for establishing itself as a QS-inhibiting agent against Staphylococcus aureus, Pseudomonas aeruginosa, etc. [69]. However, the effective laboratory application of quercetin alone has stopped because of its lesser solubility in physiological fluids [70]. Therefore, many research works convey a solubility increase strategy for quercetin, which is done in the form of an amorphous and stable complex of nanoparticles of quercetin and chitosan [71]. The preparation of this complex is done using an electrostatic method and it is performed to form a complex involving ionized quercetin components and oppositely charged ChNPs [72]. In optimal conditions, a quercetin and chitosan nanoparticle complex with a size of roughly 150 to 170 nm shows a payload of about 25 to 30% having 60 to 70% efficiency with a long storage ability. Due to the absence of any adverse side effects, the complex of quercetin and ChNPs can be used for various therapeutic purposes. Such a complex is found to be more effective in the inhibition of quorum sensing than quercetin alone. Although this complex could bring about the increased suppression of quorum-sensing-regulating genes, resulting in the haltingof swimming motility and formation of Pseudomonas aeruginosa biofilms, it could not suppress the formation of its virulence factor [33]. The prior inhibition of the production of the biofilm’s swimming motility using the quercetin and ChNPs complex revealed an almost five-fold increase in kinetic solubility [73].
    A new type of ChNPsthat are dually crosslinked with genipin and sodium tripolyphosphate (TPP) display quorum quenching activity [74].
    Trans-cinnamaldehyde (CA) is an intensively studied compound that was shown to inhibit QS activity by decreasing the DNA-binding ability of LuxR while inhibiting acyl-homoserine lactone production. In this work, chitosan-based nanocapsules laden with a high concentration of CA were applied to a transformed E. coli Top 10 strain fluorescence-based reporter [14][75].

    5. Mechanism of QS Inhibition Using Functionalized Chitosan Nanoparticles

    A nanocapsule is a shell made from a nontoxic polymer that encapsulates an inner liquid core at the nanoscale. These have many uses, including promising medical applications for drug delivery, food enhancement, nutraceuticals, and self-healing materials. The benefits of encapsulation methods are the protection of the drug and/or allied substances from the adverse environment, controlled release, and precision targeting. Hence, chitosan in the form of nanoparticles can exert its antibiofilm activity in a more targeted way. TPP-crosslinked nanoparticles (ionically crosslinked; IC-NPs) show considerable anti-quorum-sensing activity despite their inherent colloidal instability in microbiological media.
    It was found that nanocapsules can interact with bacteria via electrostatic interaction, thus effectively delivering the quorum-quenching compound CA to the bacteria. The electrostatic adsorption of the chitosan-coated nanocapsules to the bacterial cell envelope is the mechanism that underpins the observed enhancement of the QS inhibition activity [76].
    The polycationic groups in organic nanoparticles that are used for antimicrobial activity cause cell damage, perhaps via an ion exchange interaction between bacteria and charged polymer surfaces, resulting in the disruption of cellular membranes [77]. Polycationic nanoparticles can enter into cells via endocytosis, followed by the formation of nanoscale membrane holes, which leads to a final membrane translocation. [78]. The mechanism of interaction of nanoparticles on the cell surface was also reported in terms of the adsorption and penetration (or disruption) of cell membranes, triggering NP-mediated toxicity. This may include steps such as nanoparticle adhesion at the membrane/water interface, passive membrane translocation, membrane restructuring and leakage, and adhesive lipid extraction [79]. Nanoparticle translocation into a cell is observed to occur via the outer wrapping, followed by free translocation and inner attachment and embedment [80]. The adsorption of NPs leads to cell wall depolarization, inducing cellular toxicity and degradation, which allows ions to enter the cytosol. Sometimes, NPs cause irregular pits on the cell wall surface, enabling ions to enter the cell [81]. The polysaccharides of EPS interact with SO4 groups of functionalized polystyrene NPs via hydrophobic complexation, which disrupts bacterial biofilm formation [82].
    Quaternary ammonium chitosan NPs can produce long cationic polymer chains that penetrate the cell membrane and can induce ion exchange, which disrupts biofilms [83].
    The positive surface of QAS ciprofloxacin-loaded nanochitosan-coated Ti implants disintegrates the negatively charged bacteria, followed by the release of ciprofloxacin, which inhibits enzymes, including DNA gyrase, and topoisomerase causes bacterial disruption. Free radicals interact with endogenous molecular oxygen to produce ROS, superoxide hydroxyl radicals, and hydrogen peroxide, which damages the bacteria membrane integrity and causes irreparable bacteria lysis [84]. Quaternized-chitosan-loaded Ag NPs release Ag ions that disintegrate the bacteria and inhibit biofilm development [85] (Figure 2).
    Figure 2. Mechanism of inhibition of biofilm by ChNPs.

    The entry is from 10.3390/polym13152533

    References

    1. Schuster, M.; Sexton, D.J.; Diggle, S.P.; Greenberg, E.P. Acyl-homoserine lactone quorum sensing: From evolution to application. Annu. Rev. Microbiol. 2013, 67, 43–63.
    2. Rasko, D.A.; Sperandio, V. Anti-virulence strategies to combat bacteria-mediated disease. Nat. Rev. Drug Discov. 2010, 9, 117–128.
    3. dos Reis Ponce, A.; Martins, M.L.; de Araujo, E.F.; Mantovani, H.C.; Vanetti, M.C.D. AiiA quorum-sensing quenching controls proteolytic activity and biofilm formation by Enterobacter cloacae. Curr. Microbiol. 2012, 65, 758–763.
    4. Wu, C.; Yan, Y.; Wang, Y.; Sun, P.; Qi, R. Antibacterial epoxy composites with addition of natural Artemisia annua waste. e-Polymers 2020, 20, 262–271.
    5. Tavío, M.M.; Aquili, V.D.; Poveda, J.B.; Antunes, N.T.; Sánchez-Céspedes, J.; Vila, J. Quorum-sensing regulator sdiA and marA overexpression is involved in in vitro-selected multidrug resistance of Escherichia coli. J. Antimicrob. Chemother. 2010, 65, 1178–1186.
    6. Mattmann, M.E.; Shipway, P.M.; Heth, N.J.; Blackwell, H.E. Potent and selective synthetic modulators of a quorum sensing repressor in Pseudomonas aeruginosa identified from second-generation libraries of N-acylated L-homoserine lactones. Chembiochem 2011, 12, 942–949.
    7. Lahiri, D.; Nag, M.; Sheikh, H.I.; Sarkar, T.; Edinur, H.; Siddhartha, P.; Ray, R. Microbiologically synthesized nanoparticles and their role in silencing the biofilm signaling cascade. Front. Microbiol. 2021.
    8. Amara, N.; Mashiach, R.; Amar, D.; Krief, P.; Spieser, S.A.H.; Bottomley, M.J.; Aharoni, A.; Meijler, M.M. Covalent inhibition of bacterial quorum sensing. J. Am. Chem. Soc. 2009, 131, 10610–10619.
    9. Lahiri, D.; Nag, M.; Sarkar, T.; Dutta, B.; Ray, R.R. Antibiofilm activity of α-amylase from Bacillus subtilis and prediction of the optimized conditions for biofilm removal by response surface methodology (RSM) and artificial neural network (ANN). Appl. Biochem. Biotechnol. 2021.
    10. Lahiri, D.; Nag, M.; Dutta, B.; Sarkar, T.; Ray, R.R. artificial neural network and response surface methodology-mediated optimization of bacteriocin production by Rhizobium leguminosarum. Iran. J. Sci. Technol. Trans. A Sci. 2021, 45.
    11. Ramasamy, M.; Lee, J. Recent nanotechnology approaches for prevention and treatment of biofilm-associated infections on medical devices. Biomed Res. Int. 2016, 2016, 1851242.
    12. Qi, Y.; Nathani, A.; Zhang, J.; Song, Z.; Sharma, C.S.; Varshney, S.K. Synthesis of amphiphilic poly(ethylene glycol)-block-poly(methyl methacrylate) containing trityl ether acid cleavable junction group and its self-assembly into ordered nanoporous thin films. e-Polymers 2020, 20, 111–121.
    13. Peng, P.; Yang, J.; Wu, Q.; Wu, M.; Liu, J.; Zhang, J. Fabrication of N-halamine polyurethane films with excellent antibacterial properties. e-Polymers 2021, 21, 47–56.
    14. Simona, J.; Dani, D.; Petr, S.; Marcela, N.; Jakub, T.; Bohuslava, T. Edible films from carrageenan/orange essential oil/trehalose—structure, optical properties, and antimicrobial activity. Polymers 2021, 13, 332.
    15. Lequette, Y.; Lee, J.-H.; Ledgham, F.; Lazdunski, A.; Greenberg, E.P. A distinct QscR regulon in the Pseudomonas aeruginosa quorum-sensing circuit. J. Bacteriol. 2006, 188, 3365–3370.
    16. Niu, C.; Clemmer, K.M.; Bonomo, R.A.; Rather, P.N. Isolation and characterization of an autoinducer synthase from Acinetobacter baumannii. J. Bacteriol. 2008, 190, 3386–3392.
    17. Annous, B.A.; Fratamico, P.M.; Smith, J.L. Scientific status summary. J. Food Sci. 2009, 74, R24–R37.
    18. Atkinson, S.; Chang, C.-Y.; Sockett, R.E.; Cámara, M.; Williams, P. Quorum sensing in Yersinia enterocolitica controls swimming and swarming motility. J. Bacteriol. 2006, 188, 1451–1461.
    19. Nag, M.; Lahiri, D.; Ghosh, A.; Das, D.; Ray, R.R. Quorum sensing. In Biofilm-Mediated Diseases: Causes and Controls; Ray, R.R., Nag, M., Lahiri, D., Eds.; Springer: Singapore, 2021.
    20. Wand, M.E.; Bock, L.J.; Turton, J.F.; Nugent, P.G.; Sutton, J.M. Acinetobacter baumannii virulence is enhanced in Galleria mellonella following biofilm adaptation. J. Med. Microbiol. 2012, 61, 470–477.
    21. Zhu, H.; Liu, H.-J.; Ning, S.-J.; Gao, Y.-L. A luxS-dependent transcript profile of cell-to-cell communication in Klebsiella pneumoniae. Mol. Biosyst. 2011, 7, 3164–3168.
    22. Ledgham, F.; Ventre, I.; Soscia, C.; Foglino, M.; Sturgis, J.N.; Lazdunski, A. Interactions of the quorum sensing regulator QscR: Interaction with itself and the other regulators of Pseudomonas aeruginosa LasR and RhlR. Mol. Microbiol. 2003, 48, 199–210.
    23. Gram, L.; Christensen, A.B.; Ravn, L.; Molin, S.; Givskov, M. Production of acylated homoserine lactones by psychrotrophic members of the Enterobacteriaceae isolated from foods. Appl. Environ. Microbiol. 1999, 65, 3458–3463.
    24. Russo, T.A.; Shon, A.S.; Beanan, J.M.; Olson, R.; MacDonald, U.; Pomakov, A.O.; Visitacion, M.P. Hypervirulent, K. pneumoniae secretes more and more active iron-acquisition molecules than “classical” K. pneumoniae thereby enhancing its virulence. PLoS ONE 2011, 6, e26734.
    25. Sanders Jr, W.E.; Sanders, C.C. Enterobacter spp.: Pathogens poised to flourish at the turn of the century. Clin. Microbiol. Rev. 1997, 10, 220–241.
    26. Rahmati, S.; Yang, S.; Davidson, A.L.; Zechiedrich, E.L. Control of the AcrAB multidrug efflux pump by quorum-sensing regulator SdiA. Mol. Microbiol. 2002, 43, 677–685.
    27. González Barrios, A.F.; Zuo, R.; Hashimoto, Y.; Yang, L.; Bentley, W.E.; Wood, T.K. Autoinducer 2 controls biofilm formation in Escherichia coli through a novel motility quorum-sensing regulator (MqsR, B3022). J. Bacteriol. 2006, 188, 305–316.
    28. Xavier, K.B.; Miller, S.T.; Lu, W.; Kim, J.H.; Rabinowitz, J.; Pelczer, I.; Semmelhack, M.F.; Bassler, B.L. Phosphorylation and processing of the quorum-sensing molecule autoinducer-2 in enteric bacteria. ACS Chem. Biol. 2007, 2, 128–136.
    29. Lee, J.; Maeda, T.; Hong, S.H.; Wood, T.K. Reconfiguring the quorum-sensing regulator SdiA of Escherichia coli to control biofilm formation via indole and N-acylhomoserine lactones. Appl. Environ. Microbiol. 2009, 75, 1703–1716.
    30. Lim, E.-K.; Jang, E.; Lee, K.; Haam, S.; Huh, Y.-M. Delivery of cancer therapeutics using nanotechnology. Pharmaceutics 2013, 5, 294–317.
    31. Zhu, H.; Liu, H.-J.; Ning, S.-J.; Gao, Y.-L. The response of type 2 quorum sensing in Klebsiella pneumoniae to a fluctuating culture environment. DNA Cell Biol. 2012, 31, 455–459.
    32. Xue, T.; Zhao, L.; Sun, H.; Zhou, X.; Sun, B. LsrR-binding site recognition and regulatory characteristics in Escherichia coli AI-2 quorum sensing. Cell Res. 2009, 19, 1258–1268.
    33. Roy, V.; Fernandes, R.; Tsao, C.-Y.; Bentley, W.E. Cross species quorum quenching using a native AI-2 processing enzyme. ACS Chem. Biol. 2010, 5, 223–232.
    34. Bhargava, N.; Sharma, P.; Capalash, N. N-acyl homoserine lactone mediated interspecies interactions between A. baumannii and P. aeruginosa. Biofouling 2012, 28, 813–822.
    35. Khan, M.A.; Chen, L.; Liang, L. Improvement in storage stability and resveratrol retention by fabrication of hollow zein-chitosan composite particles. Food Hydrocoll. 2021, 113, 106477.
    36. Chatzitaki, A.-T.; Jesus, S.; Karavasili, C.; Andreadis, D.; Fatouros, D.G.; Borges, O. Chitosan-coated PLGA nanoparticles for the nasal delivery of ropinirole hydrochloride: In vitro and ex vivo evaluation of efficacy and safety. Int. J. Pharm. 2020, 589, 119776.
    37. Chandra, J.; Kuhn, D.M.; Mukherjee, P.K.; Hoyer, L.L.; McCormick, T.; Ghannoum, M.A. Biofilm formation by the fungal pathogen Candida albicans: Development, architecture, and drug resistance. J. Bacteriol. 2001, 183, 5385–5394.
    38. Ravishankar, R.V.; Jamuna, B.A. Nanoparticles and their potential application as antimicrobials, science against microbial pathogens: Communicating current research and technological advances. In Formatex, Microbiology Series; Méndez-Vilas, A., Ed.; SCIRP: Wuhan, China, 2011; pp. 197–209.
    39. Garg, U.; Chauhan, S.; Nagaich, U.; Jain, N. Current advances in chitosan nanoparticles based drug delivery and targeting. Adv. Pharm. Bull. 2019, 9, 195–204.
    40. Ali, A.; Ahmed, S. A review on chitosan and its nanocomposites in drug delivery. Int. J. Biol. Macromol. 2018, 109, 273–286.
    41. Pati, S.; Chatterji, A.; Dash, B.P.; Nelson, B.R.; Sarkar, T.; Shahimi, S.; Edinur, H.A.; Abd Manan, T.S.B.; Jena, P.; Mohanta, Y.K.; et al. Structural characterization and antioxidant potential of chitosan by γ-irradiation from the carapace of horseshoe crab. Polymers 2020, 12, 2361.
    42. Pati, S.; Sarkar, T.; Sheikh, H.I.; Bharadwaj, K.K.; Mohapatra, P.K.; Chatterji, A.; Dash, B.P.; Edinur, H.A.; Nelson, B.R. γ-Irradiated chitosan from Carcinoscorpiusrotundicauda (Latreille, 1802) improves the shelf life of refrigerated aquatic products. Front. Mar. Sci. 2021, 8, 498.
    43. Ghormade, V.; Deshpande, M.V.; Paknikar, K.M. Perspectives for nano-biotechnology enabled protection and nutrition of plants. Biotechnol. Adv. 2011, 29, 792–803.
    44. Dedloff, M.R.; Effler, C.S.; Holban, A.M.; Gestal, M.C. Use of biopolymers in mucosally-administered vaccinations for respiratory disease. Materials 2019, 12, 2445.
    45. Karava, A.; Lazaridou, M.; Nanaki, S.; Michailidou, G.; Christodoulou, E.; Kostoglou, M.; Iatrou, H.; Bikiaris, D.N. Chitosan derivatives with mucoadhesive and antimicrobial properties for simultaneous nanoencapsulation and extended ocular release formulations of dexamethasone and chloramphenicol drugs. Pharmaceutics 2020, 12, 594.
    46. Safdar, R.; Omar, A.A.; Arunagiri, A.; Regupathi, I.; Thanabalan, M. Potential of chitosan and its derivatives for controlled drug release applications–A review. J. Drug Deliv. Sci. Technol. 2019, 49, 642–659.
    47. Bowman, K.; Leong, K.W. Chitosan nanoparticles for oral drug and gene delivery. Int. J. Nanomed. 2006, 1, 117–128.
    48. Mushtaq, S.; Khan, J.A.; Rabbani, F.; Latif, U.; Arfan, M.; Yameen, M.A. Biocompatible biodegradable polymeric antibacterial nanoparticles for enhancing the effects of a third-generation cephalosporin against resistant bacteria. J. Med. Microbiol. 2017, 66, 318–327.
    49. Jhaveri, J.; Raichura, Z.; Khan, T.; Momin, M.; Omri, A. Chitosan nanoparticles-insight into properties, functionalization and applications in drug delivery and theranostics. Molecules 2021, 26, 272.
    50. Grenha, A. Chitosan nanoparticles: A survey of preparation methods. J. Drug Target. 2012, 20, 291–300.
    51. Shiraishi, S.; Imai, T.; Otagiri, M. Controlled release of indomethacin by chitosan-polyelectrolyte complex: Optimization and in vivo/in vitro evaluation. J. Control. Release 1993, 25, 217–225.
    52. Gondil, V.S.; Dube, T.; Panda, J.J.; Yennamalli, R.M.; Harjai, K.; Chhibber, S. Comprehensive evaluation of chitosan nanoparticle based phage lysin delivery system; a novel approach to counter S. pneumoniae infections. Int. J. Pharm. 2020, 573, 118850.
    53. Krishnasailaja, A.; Amareshwar, P.; Chakravarty, P. Different techniques used for the preparation of nanoparticles using natural polymers and their application. Int. J. Pharm. Pharm. Sci. 2011, 3, 45–50.
    54. Rizeq, B.R.; Younes, N.N.; Rasool, K.; Nasrallah, G.K. Synthesis, bioapplications, and toxicity evaluation of chitosan-based nanoparticles. Int. J. Mol. Sci. 2019, 20, 5776.
    55. Galié, S.; García-Gutiérrez, C.; Miguélez, E.M.; Villar, C.J.; Lombó, F. Biofilms in the Food Industry: Health Aspects and Control Methods. Front. Microbiol. 2018, 9, 898.
    56. Wang, L.; Hashimoto, Y.; Tsao, C.-Y.; Valdes, J.J.; Bentley, W.E. Cyclic AMP (cAMP) and cAMP receptor protein influence both synthesis and uptake of extracellular autoinducer 2 in Escherichia coli. J. Bacteriol. 2005, 187, 2066–2076.
    57. Zhou, X.; Meng, X.; Sun, B. An EAL domain protein and cyclic AMP contribute to the interaction between the two quorum sensing systems in Escherichia coli. Cell Res. 2008, 18, 937–948.
    58. Tan, Y.; Ma, S.; Leonhard, M.; Moser, D.; Haselmann, G.M.; Wang, J.; Eder, D.; Schneider-Stickler, B. Enhancing antibiofilm activity with functional chitosan nanoparticles targeting biofilm cells and biofilm matrix. Carbohydr. Polym. 2018, 200, 35–42.
    59. Yang, Y.-X.; Xu, Z.-H.; Zhang, Y.-Q.; Tian, J.; Weng, L.-X.; Wang, L.-H. A new quorum-sensing inhibitor attenuates virulence and decreases antibiotic resistance in Pseudomonas aeruginosa. J. Microbiol. 2012, 50, 987–993.
    60. Geske, G.D.; O’Neill, J.C.; Miller, D.M.; Mattmann, M.E.; Blackwell, H.E. Modulation of bacterial quorum sensing with synthetic ligands: Systematic evaluation of N-acylated homoserine lactones in multiple species and new insights into their mechanisms of action. J. Am. Chem. Soc. 2007, 129, 13613–13625.
    61. De Lamo Marin, S.; Xu, Y.; Meijler, M.M.; Janda, K.D. Antibody catalyzed hydrolysis of a quorum sensing signal found in Gram-negative bacteria. Bioorg. Med. Chem. Lett. 2007, 17, 1549–1552.
    62. Xu, N.; Yu, S.; Moniot, S.; Weyand, M.; Blankenfeldt, W. Crystallization and preliminary crystal structure analysis of the ligand-binding domain of PqsR (MvfR), the Pseudomonas quinolone signal (PQS) responsive quorum-sensing transcription factor of Pseudomonas aeruginosa. Acta Crystallogr. Sect. F Struct. Biol. Cryst. Commun. 2012, 68, 1034–1039.
    63. Kaufmann, G.F.; Park, J.; Mee, J.M.; Ulevitch, R.J.; Janda, K.D. The quorum quenching antibody RS2-1G9 protects macrophages from the cytotoxic effects of the Pseudomonas aeruginosa quorum sensing signalling molecule N-3-oxo-dodecanoyl-homoserine lactone. Mol. Immunol. 2008, 45, 2710–2714.
    64. Pustelny, C.; Albers, A.; Büldt-Karentzopoulos, K.; Parschat, K.; Chhabra, S.R.; Cámara, M.; Williams, P.; Fetzner, S. Dioxygenase-mediated quenching of quinolone-dependent quorum sensing in Pseudomonas aeruginosa. Chem. Biol. 2009, 16, 1259–1267.
    65. Calfee, M.W.; Coleman, J.P.; Pesci, E. Interference with Pseudomonas quinolone signal synthesis inhibits virulence factor expression by Pseudomonas aeruginosa. Proc. Natl. Acad. Sci. USA 2001, 98, 11633–11637.
    66. Lesic, B.; Lépine, F.; Déziel, E.; Zhang, J.; Zhang, Q.; Padfield, K.; Castonguay, M.-H.; Milot, S.; Stachel, S.; Tzika, A.A.; et al. Inhibitors of pathogen intercellular signals as selective anti-infective compounds. PLoS Pathog. 2007, 3, 1229–1239.
    67. Plyuta, V.; Zaitseva, J.; Lobakova, E.; Zagoskina, N.; Kuznetsov, A.; Khmel, I. Effect of plant phenolic compounds on biofilm formation by Pseudomonas aeruginosa. APMIS 2013, 121, 1073–1081.
    68. Adonizio, A.; Leal, S.M.; Ausubel, F.M.; Mathee, K. Attenuation of Pseudomonas aeruginosa virulence by medicinal plants in a Caenorhabditis elegans model system. J. Med. Microbiol. 2008, 57, 809–813.
    69. Sarabhai, S.; Sharma, P.; Capalash, N. Ellagic acid derivatives from Terminalia chebula Retz. downregulate the expression of quorum sensing genes to attenuate Pseudomonas aeruginosa PAO1 virulence. PLoS ONE 2013, 8, e53441.
    70. Zimmer, K.R.; Macedo, A.J.; Nicastro, G.G.; Baldini, R.L.; Termignoni, C. Egg wax from the cattle tick Rhipicephalus (Boophilus) microplus inhibits Pseudomonas aeruginosa biofilm. Ticks Tick. Borne. Dis. 2013, 4, 366–376.
    71. Skindersoe, M.E.; Ettinger-Epstein, P.; Rasmussen, T.B.; Bjarnsholt, T.; de Nys, R.; Givskov, M. Quorum sensing antagonism from marine organisms. Mar. Biotechnol. (NY) 2008, 10, 56–63.
    72. Gutierrez, J.A.; Crowder, T.; Rinaldo-Matthis, A.; Ho, M.-C.; Almo, S.C.; Schramm, V.L. Transition state analogs of 5′-methylthioadenosine nucleosidase disrupt quorum sensing. Nat. Chem. Biol. 2009, 5, 251–257.
    73. Vikram, A.; Jesudhasan, P.R.; Pillai, S.D.; Patil, B.S. Isolimonic acid interferes with Escherichia coli O157:H7 biofilm and TTSS in QseBC and QseA dependent fashion. BMC Microbiol. 2012, 12, 261.
    74. Vila-Sanjurjo, C.; Hembach, L.; Netzer, J.; Remuñán-López, C.; Vila-Sanjurjo, A.; Goycoolea, F.M. Covalently and ionically, dually crosslinked chitosan nanoparticles block quorum sensing and affect bacterial cell growth on a cell-density dependent manner. J. Colloid Interface Sci. 2020, 578, 171–183.
    75. Qin, X.; Kräft, T.; Goycoolea, F.M. Chitosan encapsulation modulates the effect of trans-cinnamaldehyde on AHL-regulated quorum sensing activity. Colloids Surf. B Biointerfaces 2018, 169, 453–461.
    76. Sun, Y.; Qin, H.; Yan, Z.; Zhao, C.; Ren, J.; Qu, X. Combating biofilm associated infection in vivo: Integration of quorum sensing inhibition and photodynamic treatment based on multidrug delivered hollow carbon nitride sphere. Adv. Funct. Mater. 2019, 29, 1808222.
    77. Lichter, J.A.; Rubner, M.F. Polyelectrolyte multilayers with intrinsic antimicrobial functionality: The importance of mobile polycations. Langmuir 2009, 25, 7686–7694.
    78. Leroueil, P.R.; Hong, S.; Mecke, A.; Baker, J.R.; Orr, B.G.; Banaszak Holl, M.M. Nanoparticle interaction with biological membranes: Does nanotechnology present a Janus face? Acc. Chem. Res. 2007, 40, 335–342.
    79. Chen, K.L.; Bothun, G.D. Nanoparticles meet cell membranes: Probing nonspecific interactions using model membranes. Environ. Sci. Technol. 2014, 48, 873–880.
    80. Lin, J.; Miao, L.; Zhong, G.; Lin, C.-H.; Dargazangy, R.; Alexander-Katz, A. Understanding the synergistic effect of physicochemical properties of nanoparticles and their cellular entry pathways. Commun. Biol. 2020, 3, 205.
    81. Slavin, Y.N.; Asnis, J.; Häfeli, U.O.; Bach, H. Metal nanoparticles: Understanding the mechanisms behind antibacterial activity. J. Nanobiotechnol. 2017, 15, 65.
    82. Nevius, B.A.; Chen, Y.P.; Ferry, J.L.; Decho, A.W. Surface-functionalization effects on uptake of fluorescent polystyrene nanoparticles by model biofilms. Ecotoxicology 2012, 21, 2205–2213.
    83. Shi, Z.; Neoh, K.G.; Kang, E.T.; Wang, W. Antibacterial and mechanical properties of bone cement impregnated with chitosan nanoparticles. Biomaterials 2006, 27, 2440–2449.
    84. Giglio, E.; Trapani, A.; Cafagna, D.; Ferretti, C.; Iatta, R.; Cometa, S.; Ceci, E.; Romanelli, A.; Mattioli-Belmonte, M. Ciprofloxacin-loaded chitosan nanoparticles as titanium coatings: A valuable strategy to prevent implant-associated infections. Nano Biomed. Eng. 2012, 4, 163–169.
    85. Huang, J.-F.; Zhong, J.; Chen, G.-P.; Lin, Z.-T.; Deng, Y.; Liu, Y.-L.; Cao, P.-Y.; Wang, B.; Wei, Y.; Wu, T.; et al. A hydrogel-based hybrid theranostic contact lens for fungal keratitis. ACS Nano 2016, 10, 6464–6473.
    More