diff --git a/src/tooluniverse/tools/nanobio/__init__.py b/src/tooluniverse/tools/nanobio/__init__.py
new file mode 100644
index 00000000..dbce0b85
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+++ b/src/tooluniverse/tools/nanobio/__init__.py
@@ -0,0 +1,7 @@
+"""
+NanoBio tools for nanotechnology and biotechnology research.
+
+Contributor: Ghassan Muammar
+Affiliation: Experts Group FZE
+License: Apache-2.0
+"""
diff --git a/src/tooluniverse/tools/nanobio/toxicity_estimator.py b/src/tooluniverse/tools/nanobio/toxicity_estimator.py
new file mode 100644
index 00000000..13cf3f9b
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+++ b/src/tooluniverse/tools/nanobio/toxicity_estimator.py
@@ -0,0 +1,75 @@
+"""
+NanoBio Toxicity Estimator Tool
+
+Author: Ghassan Muammar
+Affiliation: Experts Group FZE
+License: Apache-2.0
+
+Early-stage in-silico toxicity estimation for nanoparticles based on
+size (nm), surface charge (mV), and core material. Intended for
+research and preclinical screening only (non-clinical use).
+"""
+
+from tooluniverse.tool_registry import register_tool
+from tooluniverse.base_tool import BaseTool
+
+
+@register_tool(
+    "NanoBioToxicityEstimator",
+    config={
+        "name": "nanobio_toxicity_estimator",
+        "type": "NanoBioToxicityEstimator",
+        "description": (
+            "Estimates early-stage nanoparticle toxicity risk using particle "
+            "size (nm), surface charge (mV), and material composition. "
+            "Designed for nanomedicine research and preclinical screening."
+        ),
+        "parameter": {
+            "type": "object",
+            "properties": {
+                "size_nm": {"type": "number", "description": "Nanoparticle diameter in nm"},
+                "charge_mV": {"type": "number", "description": "Surface zeta potential in mV"},
+                "material": {"type": "string", "description": "Core material (e.g., lipid, polymer, gold)"}
+            },
+            "required": ["size_nm", "charge_mV", "material"]
+        }
+    }
+)
+class NanoBioToxicityEstimator(BaseTool):
+    def run(self, arguments=None, **kwargs):
+        if arguments is None:
+            arguments = kwargs
+
+        size_nm = float(arguments["size_nm"])
+        charge_mV = float(arguments["charge_mV"])
+        material = str(arguments["material"]).strip().lower()
+
+        score = 0.0
+        reasons = []
+
+        if size_nm < 50:
+            score += 2.5
+            reasons.append("size < 50 nm")
+        elif size_nm > 200:
+            score += 3.0
+            reasons.append("size > 200 nm")
+
+        if abs(charge_mV) > 30:
+            score += 2.5
+            reasons.append("|charge| > 30 mV")
+
+        if material in ["gold", "silver"]:
+            score += 2.0
+            reasons.append(f"material = {material}")
+
+        score = max(0.0, min(score, 10.0))
+
+        risk = "Low" if score < 3 else ("Medium" if score < 6 else "High")
+
+        return {
+            "toxicity_score": round(score, 2),
+            "risk_level": risk,
+            "reasons": reasons,
+            "confidence": 0.5,
+            "success": True
+        }