Sampa Saha

Anisotropic microgels enable spatiotemporal co-delivery through programmable drug localization.

Due to their unique shape and tendency to undergo surface modification, anisotropic particles are emerging as next-generation particle-based systems for drug delivery applications, unlike conventional spherical particles. Nonetheless, in addition to geometric factors, the inherent characteristics of the polymer matrix significantly influence the development, dimensional stability, and functional behavior of these anisotropic systems. This review paper critically analyzes the impact of matrix materials, ranging from entirely polymeric systems to polymer–inorganic hybrids, on the structural evolution, compartmentalization, and physicochemical properties of anisotropic particles as a drug delivery system. Significant attention is directed to the influence of polymer characteristics, including molecular weight, glass transition temperature, hydrophobicity, and phase compatibility, on anisotropic morphology, multi-compartment formation, and drug encapsulation effectiveness. The interaction between the matrix composition and biological performance, encompassing cellular absorption, biological distribution, vascular margination, and stimuli-responsive medication release, is thoroughly examined. The significance of matrix-driven design in facilitating multi-drug distribution, regulating release kinetics, and achieving tailored therapeutic effects is emphasized. Notwithstanding considerable advancements, issues concerning scalable production, repeatability, and the uniformity of matrix-dependent parameters persist as substantial obstacles to clinical translation. This research establishes a structure–function–performance relationship for matrix materials, providing a solid foundation for the development of a future-oriented anisotropic polymeric drug delivery system.

The domain-selective arrangement of biomolecules and cells at the microscale is essential for various biomedical applications. Recently, bio-conjugated polymer brushes have garnered immense attention from the research community. Several patterning techniques developed so far for producing microstructured biointerfaces based on polymer brushes suffer from various limitations, such as being time-consuming, costly, intricate processes created mostly for model inorganic substrates, etc. Herein, we present a simple method for creating micropatterned biofunctional brushes grafted on biodegradable polymer such as PHBV (poly(3-hydroxybutyrate-co-3-hydroxyvalerate)). Oxygen plasma-assisted surface modification followed by domain-selective SI-ATRP (surface-initiated atom transfer radical polymerization) was carried out in tandem to create an alternate pattern of poly(ethyleneglycol)methyl ether methacrylate (PPEGMA) and poly(dimethyaminoethyl) acrylate (PDMAEMA) brushes on micropatterned PHBV surfaces. Thick dual brushes were selectively grafted onto their respective regions through a masking/demasking process, reaching approximately 965 ± 40 nm for PPEGMA and 1128 ± 50 nm for PDMAEMA under the optimized grafting conditions. Domain-selective proteins, gold nanoparticles, and aptamers were immobilized on a suitable brush, avoiding the production of micropatterned biointerfaces, which was ultimately explored for cancer (HeLa) cell immobilization, especially in aptamer-deposited regions. The scope of this innovation can be extended to the micropatterning of various biomolecules, including antibodies, bacteria, and DNA. The dual brush-grafted micropatterned biodegradable polymeric surface offers a straightforward way to immobilize biomolecules, which holds immense potential as a cancer diagnostic biosensor for enhanced and regiospecific bindings, while limiting nonspecific adhesion.

1. Polyolefin polymers such as polyethylene (PE) and polypropylene (PP) are among the most widely used materials in biomedical, packaging, automotive, marine, textile, and household applications be...

Suitably functionalized polymer brush-modified micropatterned surfaces may enable precise control over interfacial interactions with multiple biomolecules, potentially leading to the creation of proteins/DNA microarrays, biosensors, diagnostics, tissue engineering, etc. Herein, we present a facile strategy to construct oppositely charged polymer brushes installed at their designated domains on the micropatterned biodegradable polymeric substrate PLA (polylactide) via SIATRP (surface-initiated atom transfer radical polymerization). Generally, it is challenging to graft polycationic and polyanionic brushes on a micropatterned surface with alternate domains of positive and negative charges. To avoid the inherent interactions between the opposite charges, this study demonstrates a unique strategy to fabricate micropatterned cationic (poly([2-(methacryloyloxy) ethyl] trimethylammonium chloride)) (PMETA) and anionic (poly(3-sulfopropyl methacrylate potassium)) (PSPMA) polymer brushes on the PLA surface. After grafting of the PSPMA brush on the desired region of the micropatterned surface (using the masking/demasking technique), tributylamine was employed to block the anionic sulfonate groups so that grafting of the cationic PMETA brush became feasible in the neighboring domain in the subsequent step. Following the polymerization of META, the anionic brushes were simply unblocked by reducing the pH of the medium, producing a micropatterned surface modified with oppositely charged polyelectrolyte brushes. As examples, oppositely charged brushes were employed to form proteins and DNA microarrays. Interestingly, while being cytocompatible and hemocompatible, the oppositely charged dual-brush-modified micropatterned surfaces were found to be highly antibacterial.

Magneto-photoresponsive polymeric microspheres represent a promising platform for targeted, externally triggered drug delivery. However, achieving precise control while minimizing phototoxicity remains a major challenge. In this study, we developed biodegradable core-shell microspheres composed of acetalated dextran (AcD) and cellulose modified by citric acid (CMC), co-loaded with a photoacid generator (PAG), Fe₃O₄ nanoparticles, and zerovalent iron (ZVI). These components enable dual-stimuli responsiveness, in which short UV exposure (365 nm, 10 min on/off cycles) and an alternating magnetic field (AMF, 150 Oe) act synergistically to enhance photoacid generation and trigger rapid drug release. Upon dual stimulation, the system exhibited rapid release kinetics, with cumulative release reaching ∼98% for curcumin within 45 min and ∼98% for doxorubicin (DOX) within 60 min. Cytocompatibility studies showed minimal toxicity toward healthy HEK293 cells, while DOX-loaded microspheres reduced viability of HepG2 liver cancer cells to ∼14% after 24 h. In 3D MCF-7 spheroid models, DOX-loaded microspheres induced significant spheroidal disintegration and a ∼41% reduction in acid phosphatase activity over 21 days. This work demonstrates a programmable, biodegradable, magneto-photoresponsive microsphere system capable of efficient and tumor-selective drug delivery, offering great potential for next-generation localized chemotherapy applications.

Micropatterned polymer brushes are a revolutionary platform that has opened up unique biomedical application possibilities through spatial control of surface characteristics. Unlike traditional polymer-brush coatings that enable homogeneous surface modifications, micropatterned brushes allow the fabrication of heterogeneous surfaces by providing localized functionality for enhanced biological interactions. This review presents different lithography techniques followed by surface-initiated polymerization as advanced fabrication methods that are vital in creating such a modulated surface architecture. Despite remarkable achievements, issues of scalability and reproducibility of the created surfaces remain a core challenge toward their industrial utilization. By critically evaluating these methodologies and their integration with biomedical technologies, we have outlined the current limitations and potential breakthroughs required for the future deployment of micropatterned polymer brushes in healthcare, particularly in areas such as biosensing, drug delivery, and tissue engineering.

Graphene-loaded AcD/CMC core–shell microspheres exhibit RF-triggered drug release and release profiles showing enhanced payload delivery under RF stimulation.

We study the stability of oil-in-water Pickering emulsions using tricompartmental brush-modified anisotropic particles (TBPs) through Dissipative Particle Dynamics (DPD) simulations. Our study examines how TBP functionality, including brush length, density, and surface modification, influences emulsion stability. We designed four distinct tricompartmental macroparticles (TPs), labeled TP-1 to TP-4, by grafting polymer brushes via surface-initiated atom transfer radical polymerization (ATRP). In TP-1 and TP-4, initiators are embedded at the central 1/3 region and on 1/3 of one side of the outer spherical surface. In TP-2 and TP-3, initiators are placed on 1/3 of both surface sides and 2/3 of the surface. We examined the kinetics of brush growth, demonstrating the linear growth of polymer brushes consistent with first-order reaction kinetics of radical polymerization. In addition, we present experimental validation of surface modification and brush growth kinetics. This combined approach offers a detailed macroscopic analysis of emulsion formation and stabilization. We show that TBP-1 results in the highest emulsion stability, followed by TBP-3 and TBP-4, whereas TBP-2 has the least stability when polymer brushes have higher local densities. Increased brush density significantly enhances emulsion stability by improving interfacial wetting. However, at lower to moderate brush densities, the stability ranking shifts to TBP-3 > TBP-4 > TBP-2 > TBP-1 for the same brush length, aligning with experimental observations. These findings highlight the effectiveness of brush-modified TPs in stabilizing Pickering emulsions and provide valuable insights for designing functional particles tailored for emulsion-based applications.

Biological barriers present remarkable challenges for therapeutics delivery, requiring an advanced drug delivery system that can navigate through the complex physiological environment. Polymeric particles provide remarkable versatility due to their adaptable physiochemical properties, facilitating new designs that address complex delivery issues. This review focuses on recent advancements in the morphology of polymeric particles that emulate biological barriers to improve drug efficacy. It includes how structural engineering─such as designing rod-shaped particles for improved cellular uptake, red-blood-cell-shaped particles for prolonged circulation, worm-shaped carriers for improved tissue penetration, and multicompartmental systems for providing combination therapies─profoundly alters drug delivery capabilities. These designer particles exhibit enhanced target specificity, controlled release kinetics, and improved therapeutic outcomes relative to traditional spherical carriers. This particular review also emphasizes how a combination of polymer chemistry and fabrication methods facilitates achieving these advanced structures, while highlighting ongoing challenges in scale-up, reproducibility, and clinical translations. Through the analysis of structure-functional property correlations in various biomimetic designs, we have also attempted to provide insight into future advancements in polymeric delivery systems that have the potential to transform treatment strategies for complicated diseases via shape-directed biological interactions for better therapeutic outcomes.