The Double-Faced Nature of Nanomaterials: The Latest Developments and Outlook on Janus Nanoparticles

S. Alex; ar1; Samson Isarel Deta 2; Hari Veluru3; Kommu Pradeep4; Vamseekrishna Gorijavolu5; A Tejasri6; Dileep Kumar Garnipudi7

Review Article - Onkologia i Radioterapia ( 2026) Volume 20, Issue 3

The Double-Faced Nature of Nanomaterials: The Latest Developments and Outlook on Janus Nanoparticles

S. Alexandar¹, Samson Isarel Deta², Hari Veluru³, Kommu Pradeep⁴, Vamseekrishna Gorijavolu⁵, A Tejasri⁶ and Dileep Kumar Garnipudi⁷^*

¹Associate Professor, Department of Pharmaceutical Chemistry, Vinayaka Mission's College of Pharmacy, Vinayaka Missions Research Foundation Deemed to b, India
²Professor, Department of Pharmacy, Komar University, Iraq
³Associate Professor, Pharmacology, MB School of Pharmaceutical Sciences, Mohan Babu University, A Rangam Peta, Tirupati, Andhra Pradesh, India
⁴Assistant Professor, Faculty of health and sciences, Villa College, Maldives
⁵Professor, Department of pharmaceutical Analysis, School of pharmacy, Dr. RVR NRIIT Deemed to Be University, Agiripalli, Vijayawada Rural, India
⁶Assistant Professor, Department of Pharmaceutical Chemistry, School of Pharmacy, Anurag University, India
⁷Research Scholar, MB School of Pharmaceutical Sciences, Mohan Babu University, A Rangam Peta, Tirupati, AndhraPradesh, India

^*Corresponding Author:
Dileep Kumar Garnipudi, Research Scholar, MB School of Pharmaceutical Sciences, Mohan Babu University, A Rangam Peta, Tirupati, AndhraPradesh, India, Email: dileepkumargarnipudi@gmail.com

Received: 08-Dec-2025, Manuscript No. OAR-25-176481; , Pre QC No. OAR-25-176481 (PQ); Editor assigned: 11-Dec-2025, Pre QC No. OAR-25-176481 (PQ); Reviewed: 19-Mar-2026, QC No. OAR-25-176481; Revised: 25-Mar-2026, Manuscript No. OAR-25-176481 (R); Published: 31-Mar-2026

Abstract

Janus nanoparticles (JNPs) are a kind of nanomaterial that has two or more distinct physical or chemical properties on different parts of the same particle. They are named after the Roman god Janus, who possessed two faces. JNPs have unique advantages in medication delivery, catalysis, self-assembly, diagnostics, and other areas since their structure and composition are not always the same. This study looks at the most recent developments in the creation, characterization, and use of Janus nanoparticles. We also discuss about the issues and possibilities that lay ahead for research and growth, as well as how they can accomplish so many various things.

Keywords

Metastatic Pulmonary Calcification; Chronic Kidney Disease; Haemodialysis; Diffuse Pulmonary Infiltrates; Metabolic Alkalosis

INTRODUCTION

Janus nanoparticles are anisotropic particles with two or more chemically or physically distinct regions within the same structure. Named after the two-faced Roman god Janus, they differ from conventional isotropic nanoparticles because they can combine varied surface chemistries, compositions, wettability, magnetic properties, optical behavior, or biological functions in one nanoscale system [1, 2]. This asymmetry gives them orientation-dependent interactions and enables multifunctional performance that is difficult to achieve with uniformly functionalized nanoparticles [2â3]. The concept of Janus particles gained attention after de Gennes introduced the idea of “Janus grains,” and research has since expanded due to their unique interfacial behavior, self-assembly ability, and multifunctionality [2â4]. Janus nanoparticles may be polymeric, inorganic, or hybrid organic-inorganic and they can exist in spherical, dumbbell-like, cylindrical, disk-like, or more complex forms [2]. Their dual architecture allows different parts of the same particle to perform separate functions, making them useful in drug delivery, bio sensing, catalysis, imaging, emulsion stabilization, and environmental applications [1â3].

Recent advances in synthesis methods, including seeded growth, phase separation, masking, Pickering emulsion techniques, template-assisted synthesis, microfluidics, and self-assembly, have improved control over Janus nanoparticle morphology and functionality [1â3],[5]. These developments have enabled the preparation of polymeric, magnetic, and hybrid Janus systems for applications such as bio-imaging, cancer therapy, Theranostics, sensing, catalysis, pollutant removal, and oil-water separation [5â8].

Despite their advantages, Janus nanoparticles still face challenges related to scalable synthesis, reproducibility, size uniformity, long-term stability, toxicity, and biocompatibility [1, 3, 7]. Therefore, this review discusses their structure, synthesis, characterization, applications, limitations, and future prospects as multifunctional nanomaterials.

Structural and Functional Classification

Janus nanoparticles can be classified based on their geometry, composition, functional domains, surface properties, and applications. Structurally, they may be spherical, dumbbell like, snowman-shaped, rod-like, disc-like, core shell-like, or branched. Binary Janus nanoparticles contain two distinct regions, while ternary or higher-order systems contain three or more functional domains. This structural separation allows different parts of the same particle to perform different roles, such as drug loading, targeting, imaging, magnetic guidance, or catalytic activity [9, 11].

Based on composition, Janus nanoparticles may be polymeric, metallic, magnetic, mesoporous, carbon-based, metal oxide, or hybrid organic-inorganic systems. Magnetic Janus nanoparticles often contain FeâOâ for magnetic separation or guidance, while mesoporous and hybrid systems are useful for drug delivery, catalysis, and environmental applications [10, 11]. Functionally, Janus nanoparticles may show hydrophilic-hydrophobic, magnetic-nonmagnetic, optical therapeutic or catalytic support behaviour. Their amphiphilic nature makes them especially useful for Pickering emulsions, oil-water separation, controlled release, and interfacial catalysis [12â15] [Table 1], [Figure 1].

Classification basis	Major types	Key feature
Geometry	Spherical, dumbbell-like, rod-like, disc-like, branched	Based on particle shape and domain arrangement
Number of domains	Binary, ternary, higher-order	Contains two or more functional regions
Composition	Polymeric, metallic, magnetic, mesoporous, hybrid	Based on materials used in each domain
Surface property	Hydrophilic–hydrophobic, magnetic–nonmagnetic, charged–neutral	Each side shows different surface behavior
Biomedical function	Drug delivery, imaging, targeting, antibacterial therapy	Combines therapeutic and diagnostic roles
Environmental function	Oil–water separation, demulsification, pollutant removal	Uses amphiphilic or magnetic properties
Catalytic function	Dual-site or tandem catalysts	Spatially separated active sites improve reactions

Table 1: Classification of Janus Nanoparticles

Figure 1: Structure Janus Nano Particle.

Synthesis Approaches

The synthesis of Janus nanoparticles is more complex than conventional nanoparticle preparation because two or more distinct domains must be formed within the same particle. Effective synthesis requires control over particle size, shape, surface chemistry, interfacial energy, and spatial separation of functional regions. Common methods include phase separation, masking and selective functionalization, Pickering emulsion techniques, seed-mediated growth, microfluidic synthesis, template-assisted fabrication, self-assembly, and electro hydrodynamic co-jetting [16â18].

Phase separation is widely used for polymeric Janus nanoparticles, where ifmmiscible polymers or phases separate during droplet solidification or solvent evaporation. Masking and Pickering emulsion methods allow selective modification of one side of a particle, making them useful for amphiphilic Janus systems [19,20]. Seed-mediated growth is commonly used for inorganic and hybrid Janus nanoparticles, where a second material grows asymmetrically on a preformed seed [21]. Microfluidic and template-assisted methods provide better control over size, shape, and compartmentalization, while self-assembly and electro hydrodynamic co-jetting are useful for soft, polymeric, and biomedical Janus systems [22â25] [Table 2].

Synthesis approach	Principle	Main advantage
Phase separation	Immiscible phases separate during particle formation	Simple and useful for polymeric Janus nanoparticles
Masking and selective functionalization	One side is protected while the exposed side is modified	Provides controlled surface asymmetry
Pickering emulsion method	Particles are positioned at oil–water or wax–water interfaces	Useful for amphiphilic Janus particles
Seed-mediated growth	A second material grows asymmetrically on a seed particle	Suitable for inorganic, magnetic, and plasmonic systems
Microfluidic synthesis	Controlled flow creates compartmentalized particles	Offers precise control over size and structure
Template-assisted synthesis	Templates guide sequential deposition or polymerization	Useful for Janus rods and wires
Self-assembly	Amphiphilic molecules or polymers organize into asymmetric particles	Useful for soft and biocompatible systems
Electrohydrodynamic co-jetting	Two polymer solutions are co-jetted under an electric field	Produces biphasic particles with nanoscale anisotropy

Table 2: Major Synthesis Approaches for Janus Nanoparticles

Characterization Techniques

Characterization of Janus nanoparticles requires multiple analytical methods because their key feature is not only nanoscale size but also asymmetric structure. A single technique is usually not enough to confirm true Janus morphology. Therefore, microscopy, spectroscopy, surface analysis, particle-size analysis, and functional testing are commonly used together to study morphology, elemental distribution, surface chemistry, crystallinity, charge, stability, and application-specific behaviour.

TEM and SEM are widely used to observe particle size, shape, surface morphology, and domain separation. EDS or EDX elemental mapping helps confirm whether different elements are located in separate regions of the same particle, while XPS, FTIR, and XRD are used to analyses surface composition, functional groups, and crystalline phases [26, 27]. DLS and zeta potential analysis provide information about hydrodynamic size, size distribution, surface charge, and colloidal stability; although they should be combined with microscopy because they cannot independently prove Janus asymmetry [27, 28]. For biomedical and functional Janus systems, CLSM, fluorescence microscopy, VSM, contact-angle analysis, and application-specific tests are used to evaluate cellular uptake, imaging ability, magnetic response, wettability, catalytic activity, drug release, or pollutant removal [29â31].

Applications of Janus Nanoparticles

Janus nanoparticles are useful in many fields because their two different domains can perform separate but complementary functions. In biomedical systems, their anisotropic structure can help combine drug loading, targeting, imaging, and stimuli-responsive release in one platform. Anisotropic drug delivery systems are especially attractive because their shape, surface chemistry, and compartmentalized structure can influence cellular uptake, circulation, and therapeutic performance [32]. Janus nanoparticles have also been explored for antibacterial therapy, where hydrophilic and hydrophobic compartments can carry different therapeutic agents for combined treatment effects [33].

In catalysis and energy-related applications, Janus nanoparticles are valuable because their different surfaces can act at interfaces or provide separated active sites. For example, photic-responsive Janus nanoparticles have been reported as interfacial catalysts for efficient biodiesel preparation [34]. In environmental applications, Janus structures are useful for oil-water separation, emulsification, pollutant adsorption, and photocatalytic degradation. A solar-driven Nano cellulose Janus aerogel showed dual functions for oil-water separation and degradation of organic pollutants [35].

Janus nanoparticles are also important in sensing, imaging, and advanced responsive materials. Plasmonic Janus particles can show optical, magnetic, and photo thermal responses, making them useful for bio sensing, phototherapy, and nanoscale manipulation [36]. Their amphiphilic nature also makes them effective stabilizers for emulsions and self-assembled structures, which is useful in nanofabrication, coatings, delivery systems, and smart materials [37].

CHALLENGES AND LIMITATIONS

Although Janus nanoparticles show strong potential in biomedical, catalytic, environmental, and interfacial applications, their practical use is still limited by several scientific and technical challenges. One major limitation is synthesis control. Janus nanoparticles require precise control over particle size, morphology, surface chemistry, and domain separation, but many fabrication methods are still complex, multistep, and difficult to reproduce on a large scale [38, 39]. Reliable large-scale preparation is especially important because current methods do not always allow systematic production of Janus particle libraries with different compositions and morphologies for property screening [38].

Another important challenge is colloidal stability and long-term performance. Janus nanoparticles are often used in complex media such as biological fluids, oil-water interfaces, wastewater, or catalytic reaction systems. In these environments, aggregation, loss of surface functionality, uncontrolled protein adsorption, or changes in wettability can reduce their performance. For biomedical applications, long-term aqueous stability is particularly important, and surface modification is often required to maintain dispensability and preserve Janus character [38]. Recent biomedical reviews also identify biocompatibility, stability, and scalability as major barriers for clinical translation of Janus particles [40].

Toxicity, biodegradability, and environmental safety are also major concerns. Some Janus nanoparticles contain inorganic metals, synthetic polymers, or non-degradable components that may cause unknown biological or ecological effects. For this reason, more attention is being given to biocompatible, biodegradable, and sustainable Janus materials. Green chemistry-based design, recovery, recycling, and reuse are important future requirements, especially for environmental and biomedical applications [41]. In addition, the number of studies on environmentally friendly and sustainable Janus particle applications is still smaller than the broader literature on Janus particle synthesis and general applications, showing that sustainability remains an underdeveloped area [41].

Finally, application-specific translation remains difficult. For drug delivery, imaging, and bio-sensing, Janus nanoparticles must show safety, reproducibility, controlled biodistribution, and clear advantages over conventional Nano-carriers. For catalysis and environmental remediation, they must remain active, recoverable, reusable, and cost-effective under real operating conditions. Therefore, future research should focus not only on designing more complex Janus structures, but also on improving scalable synthesis, reproducibility, safety evaluation, regulatory readiness, and real-world performance testing [39â42].

CONCLUSION

Janus nanoparticles represent an important class of advanced nanomaterials because they combine two or more different structural, chemical, or functional domains within a single particle. This dual-faced nature gives them properties that are not usually possible in conventional isotropic nanoparticles, including directional interactions, selective surface activity, multifunctionality, and improved performance at biological, catalytic, and environmental interfaces. Their ability to integrate functions such as drug loading, targeting, imaging, magnetic response, catalytic activity, and amphiphilic behaviour makes them highly valuable for applications in medicine, bio-sensing, catalysis, energy systems, oil-water separation, pollutant removal, and smart material design.

Recent developments in synthesis methods, including phase separation, seed-mediated growth, Pickering emulsion techniques, masking, template-assisted fabrication, microfluidics, and self-assembly, have improved the control of Janus nanoparticle morphology and composition. At the same time, advanced characterizations techniques such as TEM, SEM, EDX mapping, XPS, DLS, zeta potential analysis, XRD, FTIR, CLSM, and VSM have made it possible to better understand their asymmetric structure and functional behaviour. However, important challenges remain, especially in scalable production, reproducibility, long-term stability, toxicity evaluation, biocompatibility, cost, and real-world validation.

Overall, Janus nanoparticles provide a promising platform for the development of next-generation multifunctional nanomaterials. Future research should focus on greener and scalable synthesis, safer biodegradable materials, improved surface stability, reliable in vivo and environmental safety studies, and stronger translation from laboratory research to clinical and industrial applications. With continued progress in material design, computational modelling, and application-specific testing, Janus nanoparticles are expected to play a significant role in targeted therapy, diagnostics, sustainable catalysis, environmental remediation, and intelligent responsive systems. This conclusion is aligned with the scope of your uploaded manuscript on Janus nanoparticles.