Bang Lin Li

Natural biological systems offer a vast library of highly organized structures for material science. Among these, sporopollenin exine capsules (SECs) extracted from plant pollen represent a distinct class of sustainable biomaterials, characterized by their micronano hierarchical architecture and significant internal loading capacity. Although SECs possess exceptional mechanical robustness and chemical stability, their application in precision medicine is often limited by a lack of specific surface functionality and controllable interfacial interactions. This review comprehensively bridges the gap between raw natural structures and advanced therapeutic platforms through surface engineering. We systematically examine structure–function relationships, detailing how diverse functionalization strategies, including chemical grafting, layer‐by‐layer assembly, and biomolecular conjugation, can precisely tailor the physicochemical properties of SECs. Such modifications empower these natural scaffolds with essential capabilities, including stimuli responsiveness, active targeting, and enhanced biocompatibility. Consequently, these engineered systems demonstrate significant potential in critical areas such as oral drug delivery, tumor immunotherapy, and diagnostic sensing. Finally, we discuss current challenges regarding clinical translation and provide a perspective on developing intelligent, pollen‐based systems that meet the rigorous demands of next‐generation personalized healthcare.

Phase diagrams and specific surface area principles are core components of the physical chemistry curriculum. To strengthen the connection of fundamental physical chemistry theories and their practical relevance, a comprehensive undergraduate laboratory experiment based on the fabrication of polymeric hydrogels and aerogels was designed and implemented. Guided by the phase diagram, renewable agarose biomass is utilized to investigate the phase transition of water through the conversion of hydrogels into aerogels using different drying methods, including oven drying, vacuum drying, and freeze-drying. The experiment demonstrates that the phase-transition process governs the microstructures of dried materials. Compared with oven drying and vacuum drying routes, the freeze-drying pathway, which proceeds via the solid-to-gas sublimation, thermodynamically eliminates the capillary forces induced by gas–liquid interfaces, thereby preserving a high-fidelity porous aerogel network. To reinforce the concept that material properties are dependent on structures, a methylene blue adsorption experiment is employed to determine the specific surface area of the aerogels based on the Langmuir monolayer adsorption theory. Furthermore, because of the high specific surface area, the freeze-dried aerogels exhibit effective formaldehyde adsorption, showing their potential utility in pollutant abatement. The experiment extends the applications of physical chemistry principles to the food industry by comparing the morphological characteristics of various dehydrated fruit products. By integrating green chemistry concepts with synthesis, characterization, and practical application, this innovative teaching experiment facilitated by polymer hydrogels and aerogels not only deepens students’ understanding of phase theory and surface chemistry but also enhances their interest in the practical significance of physical chemistry knowledge.

The geometric chirality of nanoscale materials originates from the asymmetric structures of the enantiomeric molecules. Herein, we introduce a universal strategy for fabricating in situ-synthesized Au nanostructures (issAu) on biological substrates using a simple staining solution of Au precursors, surfactant, and reductant. As a proof-of-concept, we integrated this staining reaction into bacterial systems, achieving the oriented growth of issAu on organism skeletons. With the involvement of exogenous cysteine enantiomers in the staining solution, enantiomeric molecules contribute to anisotropic growth of branched issAu and the evolution of plasmonic chirality. Through reaction optimization, we successfully engineer chiral issAu onto bacteria, constructing these nanobioheterostructures as versatile, bacterium-derived nanomaterials. The simple and rapid staining method based on chiral issAu growth solutions facilitates the in situ plasmonic engineering of pathogenic bacteria, enabling optical microscopy imaging of individual microbes. Our protocol provides an approach for the chiral nanoengineering of biological entities and exhibits high potential in antimicrobial and bioanalytical applications.

Chiral gold (Au) nanostructures are typically synthesized via the addition of growth seeds to reaction solutions containing Au precursors, surfactants, and enantiomeric molecules, and the geometric chirality of these nanostructures arises from enantiomer-induced asymmetric growth. However, the influence of coexisting nonchiral surfactants in reaction solutions on the chirality evolution of nanomaterials is rarely discussed. Herein, taking cysteine and hexadecyl trimethylammonium bromide (CTAB) as examples of enantiomeric molecule and surfactant, respectively, the Au reaction solution related to the growth of chiral Au nanostructures was studied in depth. Our findings reveal that increasing concentrations of cysteine promote the formation of branched Au nanostructures. With only micromolar cysteine, it is sufficient to induce the anisotropic branched growth. Nevertheless, when the reaction rates are rapid, the impacts of cysteine on branched growth are weakened. Fortunately, CTAB with the optimal concentration (1.0 mM) serves a reaction modulator, slowing asymmetric growth while enhancing the geometric chirality features of those branched Au nanostructures. When CTAB concentrations surpass 10.0 mM, the products are mainly characterized with the assembled architectures, which detrimentally affect the chirality characteristics. This work is crucial to reveal the chirality evolution mechanism of chiral nanomaterials, remarkably guiding the mediated synthesis of unprecedent chiral nanomaterials on emerging substrates.

Inspired by the distinct circular coffee-ring stains left by coffee droplets, we explore another type of circular stain formed by colorimetric nanomaterials on hydrophilic and porous nitrocellulose (NC) papers, which are termed diffusion coffee rings (DCRs). Layered MoS₂ nanosheets, utilized as colorimetric nanomaterials, exhibit an intriguing MoS₂-marked DCR (MoS₂/DCR) boundary on NC substrates. When MoS₂-loaded NC was immersed into HAuCl₄ solutions, a spontaneous reaction between MoS₂ nanosheets and Au ions results in notable color changes at the MoS₂/DCR due to the formation of in situ-synthesized gold nanoparticles (issAu), and this phenomenon is termed issAu staining in our protocol. Herein, issAu staining is highly stable and repeatable due to the stabilization effect of NC fibers on the attached Au nanomaterials, whereas the presence of proteins effectively inhibits the growth of issAu on MoS₂, responsively weakening the staining effect. Under the inspiration of paper-based kits, we developed a simple and rapid protein analysis method based on the issAu-stained MoS₂/DCR assay (issAu-MoS₂/DCR). The MoS₂/DCR enables the desired recognition effect of proteins in the presence of coexisting compounds, ensuring high anti-interference performance. Our issAu-MoS₂/DCR analysis protocol works via the synchronous formation of Au nanoparticles, which overcomes challenges related to the drawbacks of sensing materials during their storage. The concept of issAu staining enhances point-of-care and ultrafast on-site monitoring techniques for proteins, practically addressing the emergency needs of early urinary disease diagnosis.

Nanoscale gold (Au) materials have garnered significant attention in chemical and biological analyses owing to their exceptional properties. However, their practical applications in sensing nanotechnologies are remarkably constrained by the inherent and universal drawbacks of nanomaterials. For instance, the poor stability of nanomaterials during storage substantially compromises the test repeatability and accuracy. To date, the lack of standardized protocols for the synthesis and storage of nanomaterials remains a critical barrier to the widespread applications of nanotechnologies. Without the storage, in situ-synthesized nanomaterials might offer a promising solution to overcome these storage-related challenges. In this perspective, Au nanostructures are classified into two categories: presynthesized Au (psAu) and in situ-synthesized Au nanostructures (issAu), respectively. Differing from psAu, issAu refers to protocols in which the preparation of Au nanostructures is simultaneously coupled with their concurrent functional applications. While extensive research has been conducted on psAu strategies, recent studies over the past decade have increasingly focused on issAu nanostructures. The issAu concept has exhibited boosted sensing responses and enhanced anti-interference in chemical and biological analysis. Moreover, issAu nanostructures work as intriguing signal probes, showing high potential in time-saving operation and improved selectivity and sensitivity. This perspective outlines the formation routes of issAu nanostructures and provides a comprehensive review of their unique properties and sensing applications. Additionally, a detailed comparison between psAu and issAu materials is correspondingly presented, underscoring the transformative potential of issAu nanostructures and inspiring broader applications of the in situ-synthesis concept for other vital nanomaterials.

The coffee-ring effect is an eye-catching circle originating from a material-suspended liquid droplet at a solid substrate after liquid evaporation, but the low speediness has restricted practical applications. When nanomaterial aqueous solutions are dropped onto porous nitrocellulose (NC), the liquid is immediately absorbed through the porous tunnels of paper fibers, and nanomaterials are rapidly enriched on the contact lines between droplets and membranes. We called this ultrafast variant of the coffee ring effect the "tunneling coffee ring" (TCR). When nanomaterial sizes are smaller than that of pores, a larger-diameter ring of nanomaterials quickly materializes. The real-time particle size-dependent TCRs and liquid diffusion rings exhibit a dual-ring pattern on the NC membrane. The tunneling speed of the capillary effect is so fast that the pattern appears within seconds. We apply the TCR effect as a size-surface affinity-particle/fluid separation sensor for bacteria. Dextran-modified Au and MoS₂ nanostructures are proposed to be antibody-free microbe kits. Our TCR effect is used to distinguish between particles of different sizes and affinities, which are highly relevant in complicated systems without electricity and equipment in resource-poor settings.

In this work, 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) was pre-doped into agarose hydrogels; consequently, sustained hydrogel systems with modulated release performance were constructed for simple operation and recyclability in point-of-care detection of formaldehyde (FA). With the increase in FA concentrations, the absorbance response of the supernatant solutions showed linear relationships and the color of the reaction mixtures gradually increased. The detection limit was calculated to be 0.013 μg mL⁻¹. To verify its practical application, a simple, rapid and low-cost FA detection platform was built on the basis of the optimized conditions, and the method shows the merits of simplicity, high sensitivity and selectivity. More importantly, the developed hydrogels are recyclable and can be used at least five times without any loss in sensing performance. Significantly, the sensory hydrogels can be employed by non-skilled people for monitoring food safety and applied for the practical detection of FA in foods.

The staining of modified papers with HAuCl₄ solutions enables the in situ growth of Au nanoclusters, and the improved fluorescence stability and uniform material distribution facilitate the chemical logic gates and information encryption systems.