Antimicrobial cationic polymers mainly contain two functional components: the cationic groups and the hydrophobic groups. The antimicrobial activity is influenced by the type, amount, location and distribution of these two components. This review summarizes the designs and syntheses of antimicrobial cationic polymers by controlling the above two factors. It involves the structural designs from primary to secondary structures, from covalent to noncovalent syntheses and from bulk to surface. Furthermore, it will discuss how to advance structural designs toward functional controls for optimizing the antimicrobial performances and biocompatibility of antimicrobial cationic polymers. It is anticipated that this review will provide some guidelines for developing molecular engineering of antimicrobial cationic polymers with tailor-made structures and functions.

A new method in which supramolecular polymerization is promoted and controlled through self-sorting is reported. The bifunctional monomer containing p-phenylene and naphthalene moieties was prepared. Supramolecular polymerization is promoted by selective recognition between the p-phenylene group and cucurbit[7]uril (CB[7]), and 2:1 complexation of the naphthalene groups with cucurbit[8]uril (CB[8]). The process can be controlled by tuning the CB[7] content. This development will enrich the field of supramolecular polymers with important advances towards the realization of molecular-weight and structural control.

Supramolecular chemotherapy is aimed to employ supramolecular approach for regulating the cytotoxicity and improving the efficiency of antitumor drugs. In this paper, we demonstrated a new example of supramolecular chemotherapy by utilizing the clinical antitumor drug, oxaliplatin, which is the specific drug for colorectal cancer treatment. Cytotoxicity of oxaliplatin to the colorectal normal cell could be significantly decreased by host-guest complexation between oxaliplatin and cucurbit[7]uril (CB[7]). More importantly, oxaliplatin-CB[7] exhibited cooperatively enhanced antitumor activity than oxaliplatin itself. On the one hand, the antitumor activity of oxaliplatin can reappear by competitive replacement of spermine from oxaliplatin-CB[7]; on the other hand, CB[7] can consume the overexpressed spermine in tumor environments, which is essential for tumor cell growth. These two events can lead to the cooperatively enhanced antitumor performance. Supramolecular chemotherapy can be applied to treat with spermine-overexpressed tumors. It is highly anticipated that this strategy may be employed in many other clinical antitumor drugs, which opens a new horizon of supramolecular chemotherapy for potential applications in clinical antitumor treatments.

Supramolecular polymer networks are non-covalently crosslinked soft materials that exhibit unique mechanical features such as self-healing, high toughness and stretchability. Previous studies have focused on optimising such properties using fast-dissociative crosslinks (i.e. for aqueous system, k d > 10 s -1 ). Herein, we describe non-covalent crosslinkers with slow, tuneable dissociation kinetics (k d < 1 s -1 ) that enable high compressibility to supramolecular polymer networks. The resultant glass-like supramolecular networks have compressive strengths up to 100 MPa with no fracture, even when compressed at 93% strain over 12 cycles of compression and relaxation. Notably, these networks show a fast, room-temperature self-recovery (< 120 s), which may be useful for the design of high-performance soft materials. Retarding the dissociation kinetics of non-covalent crosslinks through structural control enables access of such glass-like supramolecular materials, holding significant promise in applications including soft robotics, tissue engineering and wearable bioelectronics.Supramolecular polymer networks (SPNs) are a class of soft materials composed of linear polymers transiently crosslinked through non-covalent interactions. 1, 2 On account of the dynamic nature of these crosslinks, they can serve as sacrificial bonds to dissipate applied energy, thus imparting SPNs with remarkable material properties including high toughness, 3 enhanced damping capacity, 4 extreme stretchability, 5-7 rapid self-healing 8-10 , and reversible mouldability. 11 These superior material properties have lead to the use of SPNs as repairable electrodes, 12, 13 artificial skins, 14,15 and drug-delivery devices 16,17 . Although promising strides have been made, the material requirements for some demanding applications have not yet been met. A major limitation of SPNs is achieving extreme compressibility with ultra-high compressive strength and complete self-recovery on short time scales.Comparing covalently to non-covalently crosslinked polymers, the dissociation kinetics for dynamic networks plays a critical role in the material design and mechanical properties of the SPNs. 1 Craig and co-workers revealed that it is in fact crosslink dynamics, rather than equilibrium thermodynamics, that are paramount in determining the material properties (e.g. viscoelasticity) of SPNs. 18,19 They reported that slower dissociation kinetics resulted in more intact crosslinks within a transient network under an applied force, leading to a higher complex modulus. Holten-Anderson et al. further demonstrated control over hierarchical polymer mechanics through tuning the relative ratio of two kinetically-distinct metal-ligand crosslinks, which allowed for decoupling of the material mechanics from crosslink structure. 20 These pioneering reports established the basis for understanding the relationship between crosslink kinetics and SPN material properties.

Rational control of the cooperativity of multiple noncovalent interactions often plays an important role in the design and construction of supramolecular self-assemblies and materials, especially in precision supramolecular engineering. However, it still remains a challenge to control the cooperativity of multiple noncovalent interactions through tuning the hydrophobic effect. In this work, we demonstrate that the binding cooperativity of cucurbit[8]uril(CB[8])-mediated homoternary complexes is strongly influenced by the amphiphilicity of guest molecule side groups on account of an interplay between both classical (entropy-driven) and nonclassical (enthalpy-driven) hydrophobic effects. To this end, we rationally designed and prepared a series of guest molecules bearing a benzyl group as the CB[8] homoternary binding motif with various hydrophilic and hydrophobic side groups for cooperative control. By gradually tuning side groups of the guest molecules from hydrophilic to hydrophobic, we are able to control the binding from positive to negative cooperativity. An advanced molecular recognition process and self-assembling system can be developed by adjusting the positive and negative cooperativity. The ability to regulate and control the binding cooperativity will enrich the field of supramolecular chemistry, and employing cooperativity-controlled multiple noncovalent interactions in precision supramolecular engineering is highly anticipated.